Valley of the Mastodons – Part 2: Experimenting with an Exhibit

We could hear singing and playful shouting from the bus in front of us.  Those of us in the car behind them—a much smaller vehicle carrying an apparently more sedate group–looked at each other and started laughing.  We’d parked briefly at the edge of an enormous grapefruit orchard, its rows of trees mostly silhouettes and shadows against the moonlight.  A few people jumped out to pick grapefruit (someone knew the orchard owner; this was encouraged). And one person burst into a loud rendition of ‘O, Canada!’ somewhere in the darkness amongst the trees.

(Moon over cedars in Idyllwild–the view from my seat in the open-air seating of the Brew Pub we were visiting; image taken with my crappy cellphone)

Our jovial group was on its way back from a trip up in the mountains to Idyllwild, a beautiful little town that lived up to its name. Everything was quaint and rustic, nestled amongst giant cedars.  Getting there meant leaving the valley where the Western Science Center resides—a flat expanse of land—and then driving up narrow roads that twist as they go higher and loop back and up and around in ways that cause one to simultaneously appreciate the views and feel vaguely car-sick.

Along the way, Alton and Brett (Dooley) pointed out a specific plant dotting the landscape around us—one of the very plants depicted in the mural by paleoartist Brian Engh now hanging in the museum.

 

(The mural now hanging in the Western Science Center by Brian Engh; screenshot from his website: Dontmesswithdinosaurs.com)


(Screenshot of the lower right corner, highlighting the plant that still grows in the San Jacinto mountain area)

I knew his artwork was based on the fossil record of the Diamond Valley Lake Local Fauna, but I didn’t realize this plant existed today.  Something about that seemed marvelous to me: that here was a plant whose ancestors lived when Pleistocene animals roamed the area.  A species that survived when so many others didn’t; a connection to life thousands of years ago.

Brian’s mural depicts what might have occurred to Max, the nickname for the enormous mastodon at the Western Science Center, and only one part of the 689 mastodon fossils recovered by Kathleen Springer, Eric Scott and their team in the 1990s.  Injuries on Max’s jaw prompted Brian to research how modern bull elephants might receive similar wounds.  This depiction of two male mastodons engaged in combat–surrounded by plants, insects, birds and amphibians matching the fossil record of the area–is the result.

(Picture of Brian Engh with his original artwork in front of the mural at the Western Science Center, photo by Jeanne Timmons)

 

Twelve or so partial skeletons of mastodons went on display in the “Valley of the Mastodons” exhibit following the three-day workshop hosted by the museum. Many exhibits may have put the fossils into body displays—illustrating what each animal may have looked like as a complete skeleton.  The Western Science Center, however, kept the fossils in their jackets – offering visitors another peek into paleontological work.  Illustrations of a mastodon skeleton—the specific bones in that fossil jacket highlighted—appear above each fossil, along with where in Diamond Valley Lake it was found and what year.  Next to that, each fossil has a white board, where scientists at the workshop posed a question or highlighted their observations after studying the fossils.

 

 

(Images of one particular mastodon fossil still in its jacket, the display text above it detailing what part of mastodon anatomy is seen here and where it was found, and Kathleen Springer’s notes on it; photos by Jeanne Timmons)

 

 

(Images of a cast of Max’s skull and Dr. Alton Dooley jr’s notes on it; photos by Jeanne Timmons)

 

 

Just as visitors could ask paleontologists questions as they worked on the floor of the museum the days prior, paleontologists were available on opening night to answer questions anyone had while exploring the exhibit.

“I think it’s really fun to talk to ANYBODY about mastodons or paleontology,” Katy (Smith) explained in a phone interview prior to the event.

This sentiment seems to encapsulate the enthusiasm I witnessed by all of the scientists attending.

“’Valley of the Mastodons’ was a very new experience for me! I’ve been to lots of classic conferences, but never one that was this open to the community,” wrote Ashley (Leger) in an email. “I’ve also never put together a new exhibit during a conference!!  Having real-world paleontologists available to interact with museum-goers of all walks of life was really interesting!  I thought we got to meet a lot of wonderful folks, talk about things that interest us, and give them a whole new take on their museum.  Anyone can go to a museum and read the signage, but not everyone can ask a scientist a question and get an answer immediately.”

(Dr. Ashley Leger answering questions of a very engaged group of museum visitors on opening night of the exhibit; photo by Jeanne Timmons)

 

 

“I think what transpired on Aug 2-4, 2017 at the Western Science Center is just incredible,” Kathleen (Springer) wrote.

As mentioned earlier, Kathleen and Eric (Scott) lead a team of volunteers over 7 years of excavations in the Diamond Valley Lake area.  Before construction even began on the human-made reservoir, Kathleen maintained that fossils would be profuse at the depths they intended to dig.  This was in direct opposition to the view held by the paleontologist initially hired for the job. When digging began and bones began surfacing, however, Kathleen and her team were hired.

“The whole reason we have that collection in that museum is because she knows her geology,” Eric said in a phone interview.

“Throughout that project,” he continued, “Kathleen, and to some extent, I had to keep reminding them, ‘if you’re digging, you’re going to find [fossils].’ I don’t know [if] they didn’t want to hear it, but they had to keep being…” Here, he paused as if searching for the right word. “…encouraged. They just didn’t get the geology, even when she told them. They just kept thinking ‘this is a one-off. Or maybe a two-off.  But we can’t keep hitting this stuff, right?’ And the answer is: yes, you can.”

(Details of one of the mastodon fossils — in this case skull and tusk — in the exhibit.  None of these fossils have been on display since their discovery in the 1990s by Kathleen Springer, Eric Scott and team; photos by Jeanne Timmons.)

 

Understanding the amount of work and time Kathleen and Eric put into uncovering and caring for the 100,000 fossils now at the museum, as well as knowing that this Pleistocene treasure had been largely unstudied, Kathleen’s enthusiasm for the workshop and event is significant.

“An amazing assemblage of paleontologists came together to talk and study mastodons,” she wrote. “That combined with the ‘Valley of the Mastodons’ exhibit, and the public interaction that ensued, was just fantastic. So much collegial dialogue occurred during and has continued since.”

“I’m happy [the fossils are] in such a beautiful place,” she said, “and they’re curated so wonderfully.”

 

(Image of part of the exhibit space before it was open to the public and before most of the displays were hung; photo by Jeanne Timmons.)

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Eliann Stoffel – Unlocking the Secrets of a Forgotten Mammoth

A rather large bone, revealed by his bulldozer, prompted William McEvoy and his crew to cease work on the road and call the police. The police then called the local archaeological society, who, in turn, called an archaeologist at the local Natural History Museum.

When word got out that a mammoth had been discovered, visitors began pouring in to see the site.  Just a few miles outside of the town of Kyle in Saskatchewan, Canada, the excavation of these fragile bones from the hard clay was witnessed by an ever-growing number of people.  It is estimated that 20,000 visitors came to see the site that autumn in 1964.

Embed from Getty Images

 

Eventually, the plaster casts protecting the bones were taken to the Natural History Museum (now known as the Royal Saskatchewan Museum); radiocarbon dating was conducted.  Possible museum displays and skeletal reconstructions were discussed.

And then?

Nothing.

Once the cause of great local excitement, the bones of the Kyle Mammoth faded from view.

The references above to archaeology are not errors.  Although the bones found were paleontological in nature, the focus on the find—and, indeed, the very reason they were recently resurrected—was to determine whether there was any evidence of human-proboscidean interaction.  When no stone tools were recovered in the surrounding sediment and with no obvious signs of butchering on the bones, interest in the fossil seems to have collectively disappeared.  For over 50 years, the various bones found on that stretch of road have been shelved in the Museum’s collections.

“I had always planned on doing my thesis at the University of Saskatchewan and I knew I wanted to do my thesis on hunting and butchering strategies utilized by Paleoindian people,” explained Eliann Stoffel, a recent graduate, in an email.

Her interest was not specific to any one species of megafauna. She hoped to study any and all large animals ancient people may have hunted: camels, bison, horse, proboscidea.

“I had approached my supervisor, Dr. Ernie Walker, with this topic and he had spoken with a member of the Saskatchewan Archaeological Society, Frank McDougal, who had suggested taking a look at the Kyle Mammoth.”

Which is how the long-forgotten fossil came back into view in 2015.

“We knew that the mammoth belonged to a time when people were in North America and actively hunting mammoths so we had the possibility of finding some sort of evidence of humans on the Kyle mammoth.”

This evidence is rare in the area known as the Northern Great Plains, an area that encompasses Saskatchewan (as well as another Canadian province and five U.S. states).

“It was one of those projects,” she said later by phone, “that, as soon as it came up, I couldn’t turn it down.  It needed to be done.”

Travelling between Saskatoon and Regina (where the Royal Saskatchewan Museum and the fossil are located), Eliann spent many hours studying and analyzing the bones from the 1964 excavation.  This included five boxes of bone fragments as well as 56 complete or near-complete bones, such as vertebrae, mandible, a partial tusk, and ribs.  Also included were ungulate bones, which—like the mammoth—did not comprise a full skeleton and did not present any clear association with its proboscidean fossil companion.

 

figure-4-1-kyle-mammoth-bones-eliann-stoffel-thesis

About 20% of the mammoth skeleton survived; image courtesy of Eliann Stoffel, University of Saskatchewan

 

Eliann’s thesis presents a comprehensive taphonomic analysis of the mammoth bones, and this was done because she and her advisors “knew that we needed to keep in mind that we might not find any evidence of human involvement.”

The idea of determining who or what made any kind of marks on a fossil seems like an overwhelming challenge.  This was not an animal that died the other day.  In this case, it died roughly 12,000 years ago. That is a considerable amount of time in which—after an animal is butchered, killed or otherwise dies of natural causes–it can be scavenged after death, it can be moved and scraped by natural elements, it can be affected by its fossilization, and then possibly affected by the process of discovery (in this case, by a bulldozer). How is anyone able to read the marks on fossil bones and know what they represent?

“[T]he first giveaway is the colour,” she wrote. “Bone, when it has been buried for a long time, tends to become stained from the surrounding sediment but only the outer surface. So when someone (an excavator) knicks the bone, the unstained inner portion of the bone is exposed and tends to be a lighter colour.

“The other indicator can be the clustering of marks. [With] butchering, there tends to be more than one cut mark on the bone in the same general area, usually at muscle attachment sites, and they tend to be orientated in the same direction. Rarely do you find cut marks that intersect each other. They are usually parallel. In accidental knick marks there is usually just the single mark and it tends to be located in a spot that you wouldn’t generally find cut marks (i.e. on joint surfaces or midshaft of a long bone).”

 

figure-b-15-kyle-mammoth-eliann-stoffel-thesis

 

Photo of the Kyle Mammoth right mandible from her thesis; courtesy of Eliann Stoffel, University of Saskatchewan

 

Contrary to initial review in the 1960s, Eliann discovered a few tantalizing signs that this mammoth may have, indeed, suffered from trauma induced by ancient humans.  From a suspicious-looking lesion to a possible puncture wound on vertebrae to a puzzling set of lines in a bone fragment, there was reason to wonder whether humans had been responsible for these scars.

Ultimately, however, the first two were determined to be pathological. The lesions conform to known understanding of malnutrition in the form of osteolytic lesions.

Knowing her hope to find evidence of human interaction, I asked if this was a bit of a disappointment.

“[I]t was a bit of a kick in the knees,” she admitted, “but still a super interesting avenue of study in terms of pathology. I am more than thrilled with my findings though!”

 

figure-5-5-kyle-mammoth-eliann-stoffel-thesis

figure-5-1-kyle-mammoth-eliann-stoffel-thesisImages courtesy of Eliann Stoffel, University of Saskatchewan

 

Another startling discovery appeared in what she describes as a “spongy” bone fragment, shown above, which contain traces of blood vessels.

“I remember bringing it to my supervisor and we both scratched our heads over it…So we called on our resident bioarchaeologist Dr. [Angela] Lieverse to take a look and she wasn’t sure but suggested possibly something vascular. Sure enough, when I searched for studies fitting that criteria, a couple articles turned up. So it seems that it is an occurring phenomena but possibly not that common,” Eliann wrote.

Ultimately, Eliann determined that this was a young male woolly mammoth (between 28 – 35 years old) that was still growing at the time of its death.  She estimates it was 328.66 cm (approximately 10.8 feet) tall.  While the large open wound on one of the vertebra points to a possible puncture wound from Clovis weaponry, other pathological features point to a mammoth suffering from malnutrition.

Eliann’s enthusiasm for those who helped her in her research was apparent.

“[T]he folks at the [Royal Saskatchewan M]useum were more than happy to help in any way possible,” she expressed, “and it is something that I have always appreciated! Also my major funders [were] the Saskatchewan Heritage Foundation, the Saskatchewan Archaeological Society, and, of course, the Department of Archaeology and Anthropology at the [University of Saskatchewan].”

More than just a strenuous academic endeavor, Eliann’s research has painted a picture that has been missing for decades on a significant local paleontological find.

“The [people in the] town of Kyle identify with this mammoth.  As you come into Kyle, there’s this statue of a mammoth.  Their sign that says ‘Welcome to Kyle’ has a picture of a mammoth on it.  It’s clear that they identify with it.”

 

 

A Mammuthus primigenius-sized THANK YOU to Eliann Stoffel—not only for her time in emails and by phone–but also for her gracious permission to use a number of pictures from her work!  Her thesis is fascinating and well written.  I recommend it to all!  Eliann, may you find many mammoths with evidence of human association in the future!

Another enormous thank you to Dr. Angela Lieverse, head of the Department of Archaeology and Anthropology at the University of Saskatchewan, who was also responsible for the generous use of images from Eliann’s thesis!

And I am very grateful to Dr. Emily Bamforth at the Royal Saskatchewan Museum for connecting me to Eliann! I could not have written this otherwise. THANK YOU!!

*****

References:

  1. The Kyle Mammoth: An Archaeological, Palaeoecological and Taphonomic Analysis, Eliann W. Stoffel, July 2016, University of Saskatchewan
  2. Shedding Some Light on the Kyle Mammoth, David Zammit, Swift Current Online, Nov. 13, 2016; the article that brought Eliann Stoffel and the Kyle Mammoth to my attention!
  3. PDF about the Kyle Mammoth from the Royal Saskatchewan Museum

Screenshot Kyle Mammoth RSM

Screenshot from the aforementioned PDF of the Kyle Mammoth, Royal Saskatchewan Museum

Researching Fossil Ungulate Communities

alces-alces-porkkala-finland

Alces alces (moose), Porkkala, Finland; photo courtesy of Juha Saarinen

In their paper “Patterns of diet and body mass of large ungulates from the Pleistocene of Western Europe, and their relation to vegetation,” published this past September in Palaeontologia Electronica, Juha Saarinen, Jussi Eronen, Mikael Fortelius, Heikki Seppä, and Adrian Lister investigate fossil ungulate communities found in England, Ireland, and Germany.

Not fossil ungulates, fossil ungulate communities.

The variety of fossils studied is just one of the exciting elements of their research.  Rather than focusing on a single species—which, given the limitations of the fossil record, is usually the case—they studied groups of fossils from at least 14 different ungulate species from the Middle to Late Pleistocene.

“[W]e are now at a point,” wrote Juha Saarinen, lead author of the paper, in an email, “where enough fossil material of ungulates and pollen records have accumulated to enable such a large scale quantitative comparison of body size and diets of ungulate with local vegetation patterns in the past as we did. Comparing vegetation proxies and mammal ecometrics from fossil data using such quantitative statistical analyses as we did has, to our knowledge, never been attempted before, so that is probably the most novel achievement of this study.”

The ungainly name of ‘ungulate’ refers to hooved animals: even-toed and odd-toed (Artiodactyla and Perissodactyla, respectively). Examples include horses, deer, moose, rhinoceros, bison, pigs and hippopotamuses.

beneski-brontops-tyleri-brontothere-view-from-skull

Brontops tyleri (a type of brontothere and a Perissodactyl) at the Beneski Museum at Amherst College, Massachusetts.   Brontotheres survived until the Eocene, an era that ended approximately 30+ million years BEFORE the Pleistocene, so this animal–although an ungulate–was not part of this study. Picture taken by the author of this blog

 

Using mesowear on the fossil teeth, they were able to determine information about their diets (from browsing to grazing), and by comparing this data with the pollen record associated with the areas in which these fossils were found, they were able to tell whether they ate more browse or grass in either open or closed environments. Body mass for these fossils was calculated and then compared to the diet of these animals.

They were searching for answers to how these species adapted to the environment in which they lived.  How did their body size relate to the vegetation available? Was their body size influenced by possible predators or by other members of their species? (In other words, were they bigger to intimidate predators or were they smaller because they lived in expansive herds?) Or was thermoregulation the single determining factor in how big these animals became, as has been proposed in earlier studies?

 

Beneski - Irish elk

Megaloceros giganteus (otherwise known as Irish Elk and an Artiodactyl) in between a mastodon and a mammoth fossil at the Beneski Museum at Amherst College, Massachusetts; picture taken by the author of this blog

 

It interested me to learn that they relied on what I rather simplistically referred to as the ‘physical observation’ of fossils.

Mesowear analysis looks at the wear and shape of fossil teeth.  Various plant material affects tooth-wear in distinctly different ways, which can be seen both on the teeth themselves and in the way the teeth have evolved.

To be clear, “this is specifically wear-induced shape, not the original shape of the unworn teeth,” Juha added. “In other words, mesowear is the change in the shape of the teeth as they get worn, and different food items cause different worn shape to develop (browse maintains high and sharp features on the tooth surface, whereas grass “grinds” them down leading to them to progressively wear down lower and more blunted the more there is grass in the diet).”

hmnh-mammoth-and-mastodon-teeth

Examples of a mammoth tooth — used to eat mostly grasses and sedges — and a mastodon tooth — used to eat trees and shrubs. Notice the very different shape of these teeth for very different types of vegetation. Proboscideans such as mammoths and mastodons were once grouped in with ungulates, but this has changed. Picture taken at the Harvard Museum of Natural History by the author of this blog.

 

Obtaining data about the pollen record (non-arboreal pollen percentages, or NAP %) meant researching published information and connecting that information with the related fossil sites.

The mathematical work behind all of this–determining mesowear, animal body size, and then relating this to the available pollen record—is staggering.

Surely, I thought, isotopic analysis would have been a much easier way to obtain information about each fossil’s diet at least.  Especially given that the pollen record isn’t always available, or—in one case—runs the risk of being skewed by the defecation of Pleistocene hippopotamuses that grazed in the area.  Why, I wondered, did they rely on methods that seemed considerably more labor-intensive and potentially (to my understanding) less accurate?

“There are a number of reasons for this,” Juha explained. “First, we wanted to obtain as much palaeodietary data as possible, comprising as complete ungulate communities as possible, and this meant dealing with very large samples of fossil molar teeth. Taking isotope samples from all those teeth would have been laborious, time consuming and expensive, not to mention also slightly destructive to the fossil specimens.

cervus-elaphus-richmond-park-london-uk

Cervus elaphus (Red Deer, Artiodactyl) at Richmond Park, London; photo courtesy of Juha Saarinen. Red Deer are one of the most extensively studied animals today. You can read about another study that references Red Deer in this post.

 

“Second, stable isotopes work best at resolving herbivore diet compositions in tropical areas where carbon isotope composition reflects roughly the proportions of C4/C3 –photosynthesizing plants (roughly grass vs. browse) in diet, but outside tropical areas all plants, grasses included, are C3 photosynthesizing and the carbon isotope composition varies also considerably according to so called canopy effect (open vs. closed environment), not just according to diet, and thus isotopes would not have allowed us to estimate the amount of grass vs. browse in the Pleistocene European ungulates as consistently and quantitatively as we could with mesowear analysis.

“Third, mesowear has been specifically shown to reflect average grass vs. browse compositions in the diets of ungulate populations, without being significantly obscured by other environmental variables, such as climate or environmental openness (e.g. Louys et al. 2012, Kaiser et al. 2013). Even if mesowear is a ‘physical observation’ as you say, it has been shown to specifically reflect the amount of abrasive dietary items (mostly grass) in herbivore diets.”

The authors focused on fossil-rich sites, where they could study between 3 – 10 fossils of each species.  They made sure to include species that were browsers, grazers and mixed-feeders.

figure-1-saarinen-et-al

Screenshot of Figure 1 from “Patterns of diet and body mass of large ungulates from the Pleistocene of Western Europe, and their relation to vegetation.” Palaeontologia Electronica19.3.32A: 1-58

 

“I owe thanks to my co-authors who knew much of the available European Pleistocene mammal collections already, having experience on working on them for many years,” Juha responded when asked how they knew of or had access to so many fossils.

Adrian Lister from the Natural History Museum of London in particular has a huge amount of knowledge and experience about Pleistocene mammal collections.

“I was also in contact with the curators of the museum collections, who gave me valuable information about the how much and what kind of material they have. Also, information about important fossil finds and numbers of specimens found have often been published before in scientific journals.

“The authors of this paper represent different fields of research experience on the various aspects of the study. I started to work on this research as a part of my PhD work, and I originally planned it with my PhD thesis supervisors Mikael Fortelius, Jussi Eronen and Heikki Seppä from the University of Helsinki.

“During the work, I visited the Natural History Museum of London, where I worked together with Professor Adrian Lister, whose expertise on British Pleistocene mammals, the NHM fossil mammal collections and mammal palaeoecology in general were very important for this work.”

NHM-DrListerLyuba

Image of Professor Adrian Lister, Natural History Museum of London, with the mummified baby mammoth, Lyuba; photo courtesy of the Natural History Museum of London for this post.

 

This work was not without its challenges.  As with any study of fossils, there are limits to the number of fossils available.  While pollen record availability has increased, there is still so much more to be discovered.  And although some species–based on extant examples–do not exhibit sexual dimorphism in body size, the sex of most of the fossils they studied was indeterminate.

“Indeed, these were some of biggest challenges in this study,” Juha acknowledged, “but they were expected and nothing much could be done to completely avoid them. I would add that it was often challenging to connect the fossil mammals with associated pollen records, especially when the fossil pollen was not obtained directly from the mammal fossils. To succeed in this study, it was important to analyze lots of data in order to overcome these problems, and to ensure that the main results and conclusions of this study are robust despite of them.”

The authors of this paper considered numerous variables in their research, and they suggest that ungulate size has a lot to do with a number of factors.  This might seem obvious, but such has not been the result of past studies.  In particular, Bergmann’s rule, which stipulates that body size corresponds largely to thermoregulation (i.e.: big body size is the result of living in colder environments), has been supported before.

bison-bonasus-kraansvlak-netherlands

Bison bonasus (Artiodactyla), Kraansvlak, Netherlands;photo courtesy of Juha Saarinen. 

 

“[T]here has been a lot of discussion as to what ultimately explains the tendency of some (but not all) organisms to be larger in cold climate. This was actually one of the main questions I discussed in my PhD thesis,” wrote Juha. “Already in 1950s some researchers (e.g. Scholander 1955, Irving 1957, Hayward 1965) pointed out that increase in size alone would not give a large enough benefit for thermoregulation in cold climates, especially considering that mammals have far more effective mechanisms of keeping warm, such as thick fur.

“Since then, many authors have noted that while there is a tendency of mammals being larger in higher latitudes, there are a number of exceptions to this ‘rule’ and heat conservation alone would not explain it.

“However, body size in mammals does correlate with food quality and availability and this seems to explain most of the body size patterns observed in mammals (e.g. Rosenzweig 1968, Geist 1987, Meiri et al. 2007, McNab 2010). For example, many herbivorous mammals tend to be larger at higher latitudes because food quality is better there (e.g. because of fertile soils created by glacial erosion and because plant defense mechanisms are lower), and thus predators eating them also tend to be larger there, but for example brown bear body mass does not correlate with latitude but with distance to nearest salmon spawning areas. On the other hand, population density also affects body size through resource availability: individual body size has been noted to decrease in many species of mammals when population densities are high leading to increased intraspecific resource competition (e.g. Wolverton et al. 2009).”

The authors of this paper argue that environment–climate, open or closed vegetation, food availability and quality–and species social structure–large or small herds–affect body size.

“[T]here are many (often interconnected) factors which together affect body size,” Juha explained. “This makes it quite complicated and challenging to study what ultimately regulates body size in mammals (and other organisms).

“In fact, our results do not support Bergmann’s rule as such, because even if our analyses show that larger sizes seem to occur in some species in open environments, this is not because of low temperature, as some of the open environments were in fact quite warm. Also, we often see that when one species was particularly large in an environment, another species was particularly small under those same conditions. E.g., we found out that red deer (Cervus elaphus) tends to be large in open environments, but wild horse (Equus ferus) tends to be small in those same environments. Thus, our results do not support the assumption of Bergmann’s rule or any other “single-cause” explanation for ungulate body size variation.

“What ultimately regulates ungulate body size is primarily food quality and availability, which is affected by the interplay of vegetation structure (regulated by environmental temperature, precipitation and soil fertility), interspecific resource competition (depending on the presence of competing species) and intraspecific resource competition (depending on population density). For example, species with large population densities in open environments, such as reindeer, bison and wild horses, could be small under those conditions because of increased intraspecific resource competition, whereas species with smaller population densities in open environments, such as red deer are large under such conditions, e.g. because of abundant, high-quality food and diminished plant defense mechanics. This is also the main conclusion concerning our results of Pleistocene European ungulate body size variation.”

“I think that studying how mammals in the past interacted with their environments is important for understanding how these interactions work in general,” he concluded. “At present, environments and their mammal faunas are so heavily influenced by human activities, and they have lost so much of their original diversity, that I believe that we simply need to study fossil mammals and their palaeoenvironments to better understand how these things have worked and ‘should usually work’ in nature.”

equus-ferus-mongolian-wild-horse-lippeaue-germany

Equus ferus (Mongolian wild horse and Perissodactyl), Lippeaue, Germany;photo courtesy of Juha Saarinen. 

It was a great honor and pleasure connecting with Dr. Juha Saarinen!  Reading this paper and gaining more insight about it from him was absolutely fascinating!  An enormous thank you to him for all of his generous help!!

Additionally, Dr. Saarinen was extraordinarily kind and helpful in clarifying points about the research that I had misunderstood.  That is always appreciated.  THANK YOU!!

Reference:

  1. Saarinen, Juha, Eronen, Jussi, Fortelius, Mikael, Seppä, Heikki, and Lister, Adrian M. 2016. Patterns of diet and body mass of large ungulates from the Pleistocene of Western Europe, and their relation to vegetation. Palaeontologia Electronica 19.3.32A: 1-58 palaeo-electronica.org/content/2016/1567-pleistocene-mammal-ecometrics

3D Printing Opens Doors to Research – Jennifer Webb

Right now, in Michigan, an undergrad is studying the contours of fossils found half way around the world. Fossils that, in fact, continue to reside in their country of origin: South Africa.  She hasn’t traveled there; she doesn’t have casts of the fossils themselves.  What she does have, and what is steadily becoming available to other organizations, is access to 3D printers.

Jennifer Webb, with help from her advisor, Rachel Caspari, has been comparing 3D replicas of the famous Homo naledi fossils discovered in 2013 to the casts of early Homo sapiens fossils found in the 1960s and 1980s. Both sets of fossils were found in South Africa: Homo naledi in the Dinaledi Chamber of the Rising Star Cave, and Homo sapiens at Klasies River Mouth.  But, so far, only one set has been dated.

Maker Bot Fossils By Monica Bradburn
Jennifer Webb w/MakerBot Fossils, photo by Monica Bradburn, courtesy of Central Michigan University

 

Jennifer’s goal: to determine the age of the Homo naledi fossils by comparing their physical attributes to this set of Homo sapiens fossils.

“Because the date [of Homo naledi] is unknown,” Jennifer explained, “we can use those traits to look and see if they’re similar [to the Homo sapiens fossils from Klasies River Mouth]. And if they are similar, then they are likely to be of a similar time period or age.”

This is important, as it would help us better understand where on the evolutionary chain Homo naledi can be found, and therefore, what physical attributes and possible social behavior developed when.

Klasies River Mouth Homo sapiens have been dated to about 120,000 years ago.  The caves at this location revealed periods of human occupation through sparse human fossils, shell middens and indications of ‘hearth activity’.  (Interestingly, one of the eggshells discovered belonged to an ostrich, a species that has not existed in the area since the Late Pleistocene.)

 

Klasies River Mouth - John Atherton

 

Klasies River Mouth Cave, South Africa; image taken by John Atherton, Flickr

In contrast to the small number of fossils at Klasies River Mouth, roughly 1550 specimens were excavated at Dinaledi Chamber—the largest set of hominin fossils found in the entire continent thus far.  Absent evidence of predator damage or remains, the 15 Homo naledi skeletons appear to have been placed in that cave deliberately.

 

Dinaledi Chamber Illustration

 

Figure 3. Cartoon illustrating the geological and taphonomic context and distribution of fossils, sediments and flowstones within the Dinaledi Chamber. The distribution of the different geological units and flowstones is shown together with the inferred distribution of fossil material.
DOI: 10.7554/eLife.09561.005

 

“My professor and I,” said Jennifer, referring to Rachel Caspari, “as long as we’ve known about this species, we’ve always been interested in it.”

But the path to actually studying Homo naledi didn’t appear until this past October, when Central Michigan University opened its Makerbot Innovation Center, making it unique amongst public Midwest universities.

And with access to 3D printers, Jennifer was able to make use of the digital scans and images provided on Morphosource.org.

2016-296-02 makerbot sj

One of the Homo naledi fossils as it is being printed; image courtesy of Central Michigan University

Maker Bot Fossils By Monica Bradburn

Rachel Caspari and Jennifer Webb with a 3D replica fossil; photo by Monica Bradburn; courtesy of Central Michigan University

 

Regular 2D printing has become so fast, so cheap, and so easy.  3D printing, on the other hand, is not necessarily any of those things.  At CMU, the cost of 3D printing is $.15 per gram.  It can take anywhere from 2 hours to an incredible 24 hours for something to print, depending upon various factors.  Most of the Homo naledi fossils took between 2 – 4 hours to create.

Having access to physical replicas of the originals is, indeed, exciting, but one wonders what challenges this might also present.

“3D printers can only be so accurate,” Jennifer replied. “The ones that we use are accurate to .2 millimeter difference. So we would have to factor in that amount of error into any of our analyses.”

“When we’re looking at the 3D-printed [fossils],” she continued, “they no longer have the coloring that the [original] fossils would have, which can also sometimes better indicate any dips or grooves or mounds. The best way we have to go around that is to look at the scans and pictures that we still have access to [from Morphosource] and compare them along with the 3D fossils that we printed.”

While researchers with access to the real Homo naledi fossils could perform isotopic analysis or radiocarbon dating, these procedures are both invasive and destructive to fossils.  Jennifer prefers to observe the physical traits themselves, preserving the fossils in their entirety.

“I love to be able to look at a set of bones, examine them, look at all their features and any marks or anything that’s on them and be able to tell a story from that,” she said.

This is no surprise, given that her interest in Forensic Anthropology—her intended course of study for her Masters—was prompted by the show, “Bones,” based on the life of Kathy Reichs.

Image from Bones by Michael Desmond/FOX

Bones – Season 5 – “The Proof in the Pudding” – Emily Deschanel, Tamara Taylor and TJ Thyne; Photo by: Michael Desmond/FOX

 

“I was afraid that, because it was a TV show, in real life it wouldn’t be the same. So I shied away from it in college in the beginning and started off with a different major. And then I discovered a Forensic Anthropology course that was being offered at CMU, and I decided to give that a try.  Once I did, I realized that it was very similar; there were a lot of things that were exactly like what they portrayed on TV. So I started getting into it more, and my interest grew.”

Before graduating this December, Jennifer will be presenting her Homo naledi findings to the American Anthropological Association in November.

Maker Bot Fossils By Monica Bradburn
3D fossil replica, by Monica Bradburn, courtesy of Central Michigan University

 

Many, many thanks to Jennifer Webb for her time and her great responses to my questions! A very special thank you to Rachel E. Perkins for reaching out to me about this story.

Further Reading:

  1. Geological and taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South AfricaPaul HGM Dirks, Lee R Berger, Eric M Roberts, Jan D Kramers, John Hawks, Patrick S Randolph-Quincey, Marina Elliott, Charles M Musiba, Steven E Churchill, Darryl J de Ruiter, Peter Schmid, Lucinda R Backwell, Georgy A Belyanin, Pedro Bomhoff, K Lindsay Hunter, Elen M Feuerriegel, Alia Gurtov, James du G Harrison, Rick Hunter, Ashley Kruger, Hannah Morris, Tebogo V Makhubela, Becca Peixotto, StevenTucker; eLife, 10 September 2015
  2. We Are Made of Star Stuff, blog post on Twilight Beasts by K. Lindsay Hunter (one of the authors of the paper above and one Rising Star team who excavated the Homo naledi fossils)
  3. Fossils Come to Life 8,500 Miles Away, CMU press release by Rachel E. Perkins

 

Forthcoming books on hominins:

  1. Seven Skeletons: The Evolution of the World’s Most Famous Human Fossils, Lydia Pyne
  2. Almost Human, Lee R. Berger and John Hawks

Seven Skeletons Lydia Pyne

Almost Human Berger Hawks

 

 

 

Stegodon: Does this ancient elephant have origins in Asia?

So much has been said in recent years about the wealth of fossils in China. Almost all of it about dinosaurs: exciting new species, feathered fossils, nest upon nest of dinosaur eggs.  There is no doubt that China holds exciting clues to the history of our planet; one has only to wait to hear of the next discovery.

Within the past few months, yet another exciting find was revealed, but this time about a little known mammalian ancestor: Stegodon.

 

Stegodon by artist Hannah Stephens

Painting of a Stegodon by artist Hannah Stephenshannahleestudio.com.

 

The name Stegodon, to me, evokes ‘dinosaur’, not ‘mammal,’ but this was, indeed, an ancient animal.  Its fossils resemble those of other similar mammals, from mastodons to mammoths to today’s elephants.

 

 

Alexandra van der Geer - shrinking elephants

Figure 1: Reconstruction of four insular dwarf proboscideans with their respective mainland ancestors. Mainland proboscideans: 1, Palaeoloxodon antiquus; 2, Mammuthus columbi; 3, Stegodon zdanskyi [stegodon found in China]. Insular proboscideans: 4, Palaeoloxodon ‘mnaidriensis’; 5, Palaeoloxodon falconeri; 6, Mammuthus exilis; 7, Stegodon aurorae [a type of dwarf stegodon found in Japan]. Based on skeletons at Museo di Paleontología, University of Rome, Italy (1), American Museum of Natural History, New York (2), Taylor Made Fossils, U.S. (3), Museo di Paleontología e Geología G.G. Gemmellaro, Palermo, Italy (4), Forschungsinstitut und Naturmuseum Senckenberg, Frankfurt, Germany (5), Santa Barbara Museum of Natural History, Santa Barbara, U.S. (6), Taga Town Museum, Honshu, Japan (7). Photos 1–2, 4–7 George Lyras, photo 3 courtesy of TaylorMadeFossils.com, reproduced here with permission.

From The effect of area and isolation on insular dwarf proboscidea by Alexandra A. E. van der Geer et al; photo and caption courtesy of Dr. Alexandra van der Geer.

 

When Stegodon skulls with tusks attached have been found, many (but not all) of the tusks are close together–preventing the trunk (the ‘proboscis,’ from which this group gets its name; proboscis —> proboscidea) from hanging between them.

They lived in what is now Africa and Asia, causing continued debate over its place of origin. Until recently, the oldest known Stegodon fossil, a 6.5+ million-year-old partial molar from Kenya, was described by William J. Sanders in 1999.  That record changed this past December when Dr. Hong Ao and his colleagues published their results dating the sediment in the Lanzhou Basin, China, from which a number of fossils–including that of a Stegodon–were found.

And that Stegodon was found to be between 8 – 11 million years old.

 

GSA Geologic Time Scale - Neogene

Detail of the Geologic Time Scale, created by the Geological Society of America.  Stegodon is believed to have existed between the Miocene to the Pleistocene, a relatively small segment of time in Earth’s overall history, but still considerably longer than that of our own species!  (You can view the time scale in much better detail here.) 

 

The fossils of the Stegodon, along with at least 5 other species, were actually found in the 1980s by Professor Xing Zhang of Northwest University in China.  Given the length of time between the fossil excavations and the recent dating of these fossils, one might wonder why determining the fossil age took so long.

Dr. Ao, a scientist at the State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, and his colleagues state that western China does not have suitable material for radiometric dating, an oft-used method for this purpose.

When I asked why this was so, Dr. Ao replied by email, “Because volcanic activities are rare in western China during the late Cenozoic, it is difficult to find  in situ tephros or tuffs for radiometric dating (e.g., 40Ar/39Ar dating).”

Instead, they conducted a magnetostratigraphic study, one in which they determined the age of the rock through the polar reversal record.  Combining this with analysis of the fossils provided evidence that this Stegodon is 2 – 5 million years older than that of the Kenyan partial molar.

“We are indeed surprised by our dating results,” Dr. Ao continued, “which document that the Lanzhou Stegodon is the oldest Stegodon worldwide, although the Stegodon  fossil [was] not discovered by us. However, our dating results document it to be the oldest known Stegodon fossil.”

Dr. Hong Ao 1

 

Dr. Hong Ao 2

Dr. Hong Ao 3

Dr. Hong Ao 4

Images of Professor Yongxiang Li (from Northwest University) and his master student as well as several employed workers who helped to excavate mammal fossils, Lanzhou Basin, China; photos courtesy of Dr. Hong Ao.

 

indricotherine fossil

indricotherine fossil2

indricotherine fossil3

Images of indricotherine fossils found in Lanzhou Basin, China; photos courtesy of Dr. Hong Ao.

 

Dr. Ao himself has been working with fossils in the Lanzhou Basin for 5 years.  When asked how  he and his co-authors chose to work together on this recent paper, he wrote, “I have collaborated with them on broad subjects before, thus I [invited] them to join [in] this research.”

Finding information about this extinct species is difficult.  Unlike mammoths or mastodons, Stegodon does not appear to be a popular ancient animal.

Fortunately, Dr. Alexandra van der Geer–paleontologist, indologist, ethno-zoologist and author –has not only studied this species, she very generously made herself available for questions.  Currently, Dr. van der Geer is an Associate Researcher at both the National and Kapodistrian University of Athens and the Naturalis Biodiversity Center in the Netherlands. She is part of the Isolario project, a project that studies biodiversity and cultural evolution within an island context.

When I asked why there was such a dearth of information on Stegodon, she wrote, “We can think of several reasons for this.”

“First of all, stegodons typically are the elephants of Southeast and East Asia, where most countries did not have the resources and opportunities most Western countries had when it comes to scientific research and excavations. These activities are costly, and since they don’t have a direct use in the sense that they don’t advance the medical, technical or economic levels of a country, they have, understandably, a lower priority. Furthermore, because of this region, half the publications (especially before the 1990s or so) you can find are in Chinese or Japanese, which is not very helpful to the [English-speaking] world.

“Secondly, stegodons are forest elephants. Forest areas are very unlikely places for the long-term preservation of organic materials: everything is eaten, digested or otherwise broken down into smaller components in no time. The tropical (warm, humid) climate of these forests is not helpful either, as decomposition is much faster here. Stegodon remains only have a chance to be preserved when (1) they are covered fast, such as with river sediments, volcanic ashes etc., (2) or are in an oxygen-free environment, such as sunken deeply into a swamp, (3) or were deposited in a natural fridge such as limestone caves where they are gradually covered in clayish sediment or [travertines]. The same is valid for Palaeoloxodon, the Old World fossil elephant, but Europe has many limestone caves, which are excellent for preservation (for a nice [travertine]-preserved negative skull, see Stuttgart museum: skull cast SMNS nr. 32888 from Bad Cannstatt).

“As you can deduct from these preservation issues, it is more likely to find molars and tusks than skeletal material, which is much softer. The vast majority of proboscidean findings all over the planet consists of molars and tusks, and that is not for nothing. Inherently this means that there is much more information about their dentition and diet than about their bodies.”

I was interested in understanding why Stegodons are portrayed as hairless animals, so very similar to contemporary elephants.  Was this just an artistic guess?

“The hairlessness of stegodons is not an artistic guess but a scientific guess instead,” Dr. van der Geer answered.  “Very large animals with thick skins (pachyderms) in a (sub)tropical environment are unlikely to have a significant hair covering. Elephants lost their hairs secondarily. The information for hair growth is not lost, and baby elephants still have a thin, woolly coat. Woolly mammoths lived in the cold, temperate zones, and needed hair, so they were covered in a thick layer of hairs, and for this is evidence (mummies preserved in the permafrost), but the other mammoths (M. meridionalis, M. columbi, M. exilis, etc.), [did] not, and it’s generally assumed that they had a light coat fitting to the temperate zones.

“Tropical and subtropical stegodons almost certainly did not have any coat that’s worth mentioning. Stegodons of temperate zones, however, may have been more hairy. Indeed, the lack of hairs makes them look more like today’s elephants.”

 

Alexandra van der Geer - Stegodon ganesa-model-I.Vjdchauhan-SiwalikHills

Photo of the two life-size models of Stegodon ganesa;photo courtesy of Dr. Gerrit van den Bergh (University of Woolongong, Australia); special thanks to Dr. Alexandra van der Geer.

 

“Note, however, that the proboscis is carried very differently. Their tusks are set very close to each other, so the proboscis doesn’t fit in between as in modern elephants, Asian and African alike. This means that the mobility of their proboscis was more restricted, relative to their living relatives.”

 

Alexandra van der Geer - Flores-excavation-31-stegodon-florensis

Fossils of Stegodon florensis insularis, from Flores, Indonesia; photo courtesy of Dr. John de Vos (Naturalis, the Netherlands); special thanks to Dr. Alexandra van der Geer.

 

Alexandra van der Geer - stegodon-timorensis-mandible

Mandible (and holotype!) of  Stegodon timorensis; photo courtesy of Eelco Kruidenier (Naturalis, the Netherlands); special thanks to Dr. Alexandra van der Geer.  Anyone familiar with proboscidean teeth and jaws will recognize the similarities instantly.

 

But how do we know that Stegodon–a rather enormous animal–evolved into something smaller?

“[D]warfs and giants are relative. Something can be a dwarf, yet have a considerable size. When we speak of dwarf stegodons, we mean stegodons that are much smaller than their ancestors. For this, you have of course to have identical or otherwise similar elements from both the descendant and the ancestor in order to compare reliably,” she continued.

“The expectation is that dwarf stegodons must have existed on the islands, following the so-called island rule, according to which large animals get smaller in isolation. There is sound evidence that this rule still stands, and is even more pronounced for fossil species (see Lomolino et al., 2013, in Journal of Biogeography).

“Indeed, the many fossil molars from the Southeast Asian islands (‘Wallacea’) are all much and much smaller than the same molars from their mainland ancestors (see Van den Bergh, 1999). True, you first have to know what is the ancestor, and for this you need information about morphology, or how the molars, tusks, skulls and postcranial elements look like. After that, you compare the sizes.

“Note that if a molar is, for example, half the length of the same molar of its ancestral species, the body weight of that animal must have been a quarter of that of its ancestor! (the cubic law: linear reduction 50% means volume reduction 50% of 50%).”

Alexandra van der Geer - Flores-stegodon-florensis

Molar of Stegodon florensis; photo courtesy of Dr. Gerrit van den Bergh (University of Woolongong, Australia); special thanks to Dr. Alexandra van der Geer.  

 

“The most interesting dwarf stegodon is Stegodon sondaari, named after the Dutch palaeontologist Paul Yves Sondaar (1934-2003), expert in fossil insular mammals. This stegodon lived on the island of Flores about a million years ago, and weighted only about 15% of the weight of its ancestral species, S. elephantoides (see Van der Geer et al., 2016, in Journal of Biogeography, doi:10.1111/jbi.12743).

“Sondaar’s dwarf stegodon is not the smallest stegodon, that honour goes to the Sumba stegodon (S. sumbaensis), of only 8% of the original weight. Sondaar’s stegodon is interesting because it may have witnessed the arrival of early humans, possibly the ancestors of the Hobbit, or Homo floresiensis. Its fossils are contemporaneous with primitive lithic artefacts, dated to about a million years ago (see Brumm et al., 2010, in Nature 464, pp. 748–752).”

 

Alexandra van der Geer - Sumba-stegodon-sompoensis-holotype-in-Naturalis-Leiden-2

Molar (and holotype!) of Stegodon sompoenisphoto courtesy of Dr. Gerrit van den Bergh (University of Woolongong, Australia); special thanks to Dr. Alexandra van der Geer.  

 

“[R]ecently,” she concluded, “one of the island dwarf stegodons (S. timorensis of Timor) has been dated to about 130 thousand years ago (see Louys et al., 2016, in PeerJ 4:e1788). This excludes, according to the authors, an anthropogenic cause for its extinction, because humans had not yet arrived at the island.”

 

*****************

So many people helped with this blog post!  (But please remember that any errors are my own.)

Many, many thanks to Dr. Hong Ao (Dr. Ao Hong) from the State Key Laboratory of Loess and Quaternary Geology (Chinese Academy of Sciences) for his fascinating responses and the great images of fossil excavations in the Lanzhou Basin.  I am thrilled that he was willing to answer questions about his research and that of his colleagues! It was a great honor and a pleasure connecting with him!

I am indebted to Dr. Alexandra Van der Geer, who very kindly (and so very quickly–despite everything else she has going on!!) answered specific questions about Stegodon that I could not find anywhere else and who provided pictures of dwarf Stegodon fossils.  It was an equally great honor and pleasure connecting with her!

A mastodon-sized thank you to the amazing Dr. Katy Smith for providing needed and hard-to-find material on Stegodon fossils!

And an enormous thank you to artist Hannah Stephens for her depiction of a Stegodon as it may have appeared in life.  I am particularly moved by the warmth of its intelligent-looking eyes, and I love the tones within its skin.  I adore this picture.  I am grateful to have it in this post;  I am thrilled to have the actual painting hanging on my wall!  Please be sure to check out her artwork at: http://hannahleestudio.com or http://hstephens.blogspot.com

*****************

References from Dr. Alexandra Van der Geer:

  1. Brumm A, Jensen GM, van den Bergh GD, Morwood MJ, Kurniawan I, Aziz F, Storey M (2010) Hominins on Flores, Indonesia, by one million years ago. Nature 464, 748–752.
  2. Lomolino MV, van der Geer AAE, Lyras GA, Palombo MR, Sax DF, Rozzi R (2013) Of mice and mammoths: generality and antiquity of the island rule. Journal of Biogeography 40, 1427–1439.
  3. Louys J, Price GJ, O’Connor S. (2016) Direct dating of Pleistocene stegodon from Timor Island, East Nusa Tenggara. PeerJ 4:e1788
  4. van den Bergh GD (1999) The Late Neogene elephantoidbearing faunas of Indonesia and their palaeozoogeographic implications; a study of the terrestrial faunal succession of Sulawesi, Flores and Java, including evidence for early hominid dispersal east of Wallace’s line. Scripta Geologica 117, 1–419.
  5. van der Geer AAE, van den Bergh GD, Lyras GA, Prasetyo UW, Due RA, Setiyabudi E, Drinia H (2016) The effect of area and isolation on insular dwarf proboscideans. Journal of Biogeography, doi: 10.111/jbi.12743

References used in this blog post:

  1. New magnetochronology of Late Miocene mammal fauna, NE Tibetan Plateau, China: Mammal migration and paleoenvironments; by Hong Ao, Peng Zhang, Mark J. Dekkers, Andrew P. Roberts, Zhisheng An, Yongxiang Li, Fengyan Lu, Shan Lin, Xingwen Li; Earth and Planetary Science Letters; 1o December 2015
  2. Oldest record of Stegodon (Mammalia: Proboscidea); by William J. Sanders; Journal of Vertebrate Paleontology; Vol. 19, No. 4, Dec. 13, 1999, pp. 793 – 797
  3. Fossil elephantoids, Awash paleolake basins, and the Afar triple junction, Ethiopia; by Jon E. Kalb; Palaeogeography, Palaeoclimatology, Palaeoecology; 1995, pp. 357 – 368
  4. The effect of area and isolation on insular dwarf proboscidea; by Alexandra A. E. van der Geer, Gerrit D. van den Bergh, George A. Lyras, Unggul W. Prasetyo, Rokus Awe Due, Erick Setiyabudi, and Hara Drinia; Journal of Biogeography; 11 March 2016.
  5. Magnetostratigraphy – concepts, definitions, and applications, by Cor G. Langereis, Wout Krijgsman, Giovanni Muttoni, and Manfred Menning; Newsletter on Stratigraphy, Vol. 43/3: 207–233, April 2010
  6. Mammoths and Mastodons of the Ice Age, by Adrian Lister, Firefly Books, 2014
  7. Mammoths, by Adrian Lister and Paul Bahn, University of California Press, 2007
  8. The Proboscidea: Evolution and Palaeoecology of Elephants and Their Relatives, Edited by Jeheskiel Shoshani and Pascal Tassy, Oxford Science Publications, 1996
  • Stegodontidae: evolutionary relationships by Haruo Saegusa, pp. 178 – 190, The Proboscidea: Evolution and Palaeoecology of Elephants and Their Relatives
  • Palaeobiogeography of late Neogene African and Eurasian Elephantoidea by Jon E. Kalb, David J. Froehlich, and Gordon L. Bell, pp. 117 – 123, The Proboscidea: Evolution and Palaeoecology of Elephants and Their Relatives

Meet Dr. Katy Smith – Mastodon Detective

If you imagine the Great Lakes region over 10,000 years ago, you might see large, hairy beasts with relatively straight tusks grazing around boggy areas or moving within dense forests.  Their fur and overall appearance might cause you to confuse them with woolly mammoths, but these are the mammoths’ shorter, stockier cousins.  And if any of them would let you get close enough to inspect their mouths, you’d see in an instant that their teeth are completely different than those of mammoths.

 

[image of contemporary boggy area in Alaska, courtesy Getty Images]

 

Whereas mammoths are believed to have eaten grasses and even flowers, mastodons needed teeth suited to the mastication of hardier stuff: shrubs, parts of trees, perhaps pinecones?   Mastodon teeth, with the bumps and ridges one might associate with carnivores, are easily recognizable as ‘teeth.’  Mammoths, in contrast, needed to grind food, producing teeth with spherical lengths of ridges across each tooth.

ISM - Mastodon tooth

 

[image courtesy of Ron Richards, Indiana State Museum, for this post: Mammoths and Mastodons in Indiana – Part 1.  Can you tell which tooth belongs to which species?]

 

ISM - Mammoth tooth

 

[image courtesy of Ron Richards, Indiana State Museum, for this post: Mammoths and Mastodons in Indiana – Part 1.]

And while woolly mammoths pervade popular culture and interest, there are some, like Dr. Katy Smith, Associate Professor of Geology at Georgia Southern University and Curator of the Georgia Southern Museum, who prefer their lesser-known cousins and have made fascinating contributions to our understanding of them.

Mastodon discoveries usually produce the fossils of a single animal, and rarely a complete skeleton. Rarer still, finding skeletal remains of multiple mastodons at the same site.

Such a unique discovery occurred in 2005, when more than 300 fossils were found in Hebron, Indiana.  Now known as the “Bothwell site,” it was originally going to be the location of the landowner’s pond.  Instead, Indiana State Museum paleobiologist Ron Richards and his crew uncovered bones that included numerous mastodons (Mammut americanum), giant beaver (Castoroides) and hoofed animals with even-toes (artiodactyls).

ISM - 2005 Bothwell Mastodon 2

 

ISM - 2005 Bothwell Mastodon 1

[images of the Bothwell site dig, courtesy of Ron Richards, Indiana State Museum, for this post: Mammoths and Mastodons in Indiana – Part 2.]

 

Four years later, the Bothwell site became the focus of Katy Smith, her dissertation, and two subsequent papers she co-wrote with Dr. Daniel Fisher at the University of Michigan.

But let’s take a moment to consider what paleontologists uncover. However rudimentary this may seem, it is important to note that bones are generally not discovered in neat order, intact and with each skeletal component attached where it would have been in the life of the animal.

Consider, too, that not all bones survive.  And those that do are often broken or in terrible condition.

So even at a site such as Bothwell, which produced lots of fossils, a paleontologist’s job is no less challenging.  The pieces of information are incomplete, mere clues to the animals that died there.

The questions, however, are profuse.

Why were so many animals found in that one spot?

If, as it is currently debated, mastodons shared behavioral traits with modern-day elephants, was this a family unit?

If so, was this group—like elephants–comprised largely of female and juvenile mastodons?

And why were other unrelated animals discovered among them?

Did a sudden disaster kill them all?  Were humans involved?

 

Embed from Getty Images

 

Sexual dimorphism is another way of referring to the traits that make an animal either female or male.  Some of us would assume, since mastodon pelvic bones were not among the Bothwell fossil assemblage, that the sex of these animals would remain unknown.

There were 13 mastodon tusks, only four of which were complete. And this, remarkably, is what prompted Katy Smith’s research.

“I wanted to know if I just had tusks, what can I do to figure out if I’m looking at a male or a female,” she explained by phone.

Katy Smith - measuring an African elephant tusk

 

[image of Dr. Katy Smith measuring an African elephant tusk in (what this author believes must be one of the greatest places on earth) the basement and fossil collection of the University of Michigan; courtesy of Dr. Katy Smith]

 

“Other people have looked at [sexual dimorphism], but I wanted to look at it specifically with the Bothwell mastodons, because they were inferred to be female, and female mastodons are less common in the fossil record than males.

“When I presented preliminary results from my research in a paleontology class, the professor said, ‘Why don’t you try multivariate analysis?’ And it just kind of spiraled from there.”

Multivariate analysis,’ as the name implies, means using more than one type of measurement or observation towards a hypothesis.  In other words, rather than simply using size as a determination of sexual dimorphism, applying numerous methods and statistics that support or disprove it.

Already, the amount of information scientists have pulled from tusks alone is fascinating.

Tusks are teeth.  They are described, in Dr. Smith’s dissertation as “hypertrophic incisors.” And, unlike human teeth, they continue to grow the entire life of the animal. So where we can simply look at a human tooth and know immediately whether it is from an adult or a child, the same cannot be done with tusks.

What their hardy structure records includes the age of the animal, growth in winter or summer months each year, their overall diet, and periods of nutritional stress.  (As described in an earlier post, Proboscidean molars can even provide details regarding where they roamed during life.)

But much of this information can only be gleaned from well-preserved, intact tusks, as well as from cutting into and examining their chemical composition.

“If you don’t know what the sex of the animal is before you look at tusk microstructure,” she said, “it can be hard to interpret what you’re looking at.”

Part of what Dr. Smith hoped to discover were similarities in the tusks where sex and age had already been determined.  If certain structural elements were the same across female mastodon tusks, such that they tended to differ from male mastodon tusks, this might help determine sexual dimorphism in future tusk discoveries.

She also hoped to discover any similarities between the tusks of extant elephants and mastodons.

Katy Smith -longitudinally bisected tusk

 

[image of longitudinally bisected tusk, courtesy of Dr. Katy Smith] 

 

Thus, she studied and measured tusks of both species from numerous museum collections. (Asian elephant tusks were not used, as female elephants of this species tend to have either tiny tusks or no tusks at all.)  She rather amusingly refers to the approximate amount of tusks involved as “5,000 pounds of tusk.”

Her dissertation and the two papers describe the type of analysis performed in detail.  Among them were canonical variates analysis (CVA) and discriminant function analysis (DFA).

“Fortunately, we didn’t have to cut into the tusks to do those measurements. You just insert a stiff wire into the pulp cavity.”

“We think about tusks sometimes as stacks of sugar cones, because they actually grow in a kind of [layered] cone structure. So you think about one sugar cone, and then you put another one inside that one and then another one inside that one and so on and so forth. And the last sugar cone is empty. There’s nothing in it. That represents the pulp cavity.”

“[Analyzing the] pulp cavity is probably one of the best single measurements that you can use to distinguish between male and females. [I]n females, that pulp cavity will terminate before the gum line, and in males, it will terminate after the gum line, closer to the tip.

“This is something that we saw in almost every mastodon. So it was kind of cool.”

 

Katy Smith - female mastodon

 

[image of female mastodon skull and tusks, courtesy of Dr. Katy Smith]

 

“If we could have cut every tusk, I would have,” she admitted, and laughed. “But it was a matter of collecting these measurements at different museums. And so I would just go there and collect all of them, and that was how we’d get the pulp cavity depth.”

“I’ve always been interested in paleontology,” she said when I asked her how she got started.

“I’m one of those kids who just never grew out of it. My parents used to take me to the museum all the time, and I used to spend hours and hours staring at the dinosaur dioramas there, just loving it.  I told my kindergarten teacher I wanted to be a paleontologist. I never changed! My 5-year-old self grew up and became a paleontologist.”

But her interests moved away from dinosaurs when she realized that their fossil record in Wisconsin, her home state, was rare to nonexistent.

After all, she said, “I started just wanting to explore what was underneath my feet.”

It wasn’t until grad school at Michigan State, where she met the late Dr. Alan Holman, that she realized her passion for mastodons.  His own interest in the species was infectious, and it was through him that she learned of the numerous mastodon (Mammut americanum) fossil discoveries in the area.

“Wow!” she said, recalling her initial reaction. “There are over 300 mastodons in Michigan. This is exciting!”

Katy Smith - male mastodon

[image of male mastodon skull and tusks, courtesy of Dr. Katy Smith]

Not surprisingly, she did her PhD work at the University of Michigan, home to Proboscidean expert Dr. Daniel Fisher, who was her advisor.

“I wanted to work with him,” she explained, “because I wanted to continue working on mastodons, and he had a couple of ideas for projects. One of them included this assemblage of mastodons from Indiana, which were—supposedly—all female.”

What she discovered regarding the Bothwell site is both thought-provoking and fascinating:

  • 8 tusks were determined to be female; the other 5 are unknown
  • the ages of the mastodons range between 19 and 31 years old
  • there is evidence that at least one juvenile might have been among them (a “juvenile tooth crown” was found)
  • given that two mastodons died in winter, and another two died either in late summer or early autumn, this indicates that the collective deaths of these animals didn’t happen at the same time (hence, not a single event)
  • none of the mastodons appeared to be under nutritional stress when they died
  • members of a family unit would be expected to have the same “isotope profiles”–chemical signatures in their teeth–but these do not

Based on the evidence provided, Dr. Smith wonders whether these animals were part of a meat cache for humans (members of the Clovis culture) that co-existed at that time.

But perhaps the single most remarkable result of her research is helping other paleontologists–who often have nothing more than a single tusk–determine the sex of that animal using her different types of analysis.

Prior to her dissertation, only one female mastodon tusk had been analyzed for growth rate.  To date, I am unaware of any other publication (paper or book) that helps detail the sexual dimorphism in mastodons by tusks alone.

When I remarked upon this, I asked her if others had cited her work.  Her response, after stating that others had, was equally fascinating to me.

“It’s always the hope as a scientist that you’re contributing in some way,” she said, “and you know that you’re contributing if somebody else is using what you’ve done.”

 

An enormous and sincere THANK YOU to Dr. Katy Smith for her generous and fascinating answers to my many questions, her gracious help when I had trouble understanding certain points, and for being so much fun with whom to connect! I cannot express how much I wish I could attend her classes, nor how fascinating I found her dissertation. I am profoundly grateful that she shared it with me!

A sincere thank you to my Dad, as well, for helping me understand tooth components (i.e.: dentin, cementum)!

**A quick reminder that I am neither a scientist nor a paleontologist, so any errors in this post are my own.

Bothwell Mastodont Dig, courtesy of Indiana State Museum; many thanks to Bruce Williams and Leslie Lorance!

—————

References:

 

Other references:

 

Cohoes mastodon size comparison

[image of sign in the NY State Museum illustrating the size difference between an extant elephant, a woolly mammoth and the Cohoes mastodon; picture taken by the author]

From the Depths of an Indiana Cave: A Fossil Treasure Trove

Around perhaps 25,000 years ago in Southern Indiana, an injured Dire Wolf made its way into a cave and never came back out. With three good legs and one that had been out of socket for a year or so, the wolf crawled through the smaller spaces and eventually—whether through an accidental fall or otherwise—landed at the bottom of a deep pit. It was trapped.

Ron Richards, Senior Research Curator of Paleobiology at the Indiana State Museum, and his crew discovered its skeleton after digging in that particular room for 3 or 4 seasons.

Ron took that set of bones to pathologists for more information. However long that injury was sustained, and it was not a short amount of time, that wolf was a survivor. They determined the one leg probably didn’t touch the ground, but that it could probably still run using the other three.

“What normally is a circular ball-joint on his thighbone was flattened on one whole side,” Ron explained in a phone interview.

“I think that probably affected his ability to back out. Maybe he smelled some rotting carcass smell or something, got too near and couldn’t back out, and probably went over the top [of the pit.]”

A reconstruction of that event, complete with an actual cast of that specific room in the cave, can be seen at the Indiana State Museum today.

What may not be apparent was the work involved in creating that cast.

The word “cave” might invoke images of enormous open spaces underground. This is not at all that kind of cave. Not at the initial opening, nor at any space within as one moves deeper inside.

“Years ago, you had to go into a belly-crawl,” Ron said of the entrance, “but now we’ve moved through it so much, we can do a hands-and-knees crawl.”

They built a platform to work above water pooling at the bottom of the pit, and—in order to keep the walls dry for rubber molds—they used blowtorches. Ron, cave dig crewmembers and people from RCI (Research Casting International) worked together on the beginning stages of the room’s cast. The finished product was done at RCI headquarters in Ontario.

RCI - Dire wolf replica

[Image of the cave cast and wolf replica, http://www.rescast.com, by Research Casting International for the Indiana State Museum]

Nothing done in that cave is an easy process.

When Ron first began digging in that cave, he said, “I thought it would take 9 people 9 days, and we could finish the project.”

That was in 1987. The dig was prompted by the discovery of a single peccary bone.

Ever since, for approximately two weeks each year, Ron and his crew have returned to dig.

“[It was] the first big cave dig we had done,” he continued, describing that first year. “We’d done a couple of mastodon digs at the time, but we really had no money for the budget. There was nothing there. We had no trained staff. We had almost no equipment.”

“I remember pulling this together, pulling different people from different sections of the museum.”

And when it came to potential funding for this excavation, Ron recalled that he was asked, ‘Can’t you do this another time?’

“I didn’t know what to say,” he admitted, “so I didn’t say anything. The next day, we got the gear loaded, and we headed down for the cave. We just did not look back!”

“As it worked out, we dug, we found more bone: parts of little peccaries, parts of big peccaries, and other animals that no longer occur in the region.”

Peccaries are relatives of modern pigs, but instead of upper canine teeth that curve up—as in modern hogs—their teeth “drive straight down like daggers,” as Ron explained. Today, modern peccaries live within the Southwest United States, as well as in Central and South America. But during the Ice Age, peccaries were common in Indiana and Eastern U.S.

Peccary Fig 02  iceage13a upgraded

[Pleistocene peccary by Karen Yoler, image courtesy of Ron Richards, the Indiana State Museum.  Per Ron Richards: “This image is artist Karen Yoler’s  concept of what the peccary looked like.  We did drop off the larger dew claws on the front legs and added a little more canine tooth size and gave it a more perpendicular orientation.”]

 

Embed from Getty Images

[Angry javelina–or collared peccary–close up. Javelina go by many names such as wild pig,boar,etc.; image and caption from Getty Images.]

Working deep in the cave initially, the crew created a system that they continue to use, with some improvements, to this day: some people dig in the cave and place the soil into buckets; other people haul the buckets out of the cave and bring them down to a stream; still others screen the soil for fossils.

All of the data is recorded; all of the soil is screened.

“Above you are big spiders—lots of cave spiders and cave crickets. They don’t bother you, but some people get the heebie-jeebies, you know? I mean, you look up, and there [are these] massive things moving around,” he said and chuckled.

In recent years, they’ve developed what Ron refers to as “tramways,” 60-70 feet of ramps created by parallel boards with cross slats. Tramways—some with rollers—help bring the buckets out of the entrance to the cave and down the hillside.

ISM - Cave with tramway

 

[Digging…with the tramway in position for hauling buckets of sediment out, image courtesy of Ron Richards, the Indiana State Museum.]

To help carry 15-20 buckets at a time down to the spring to be screened, they employ an ATV with a tractor.

“[From all of the] tons of soil that gets screened,” Ron stated, “[there remains some] soil that’s left with small bones. We bag that out, bring it back to the museum, and then they rescreen it and clean it. And then–spoonful by spoonful–they go under the binocular microscope, and they pick out all the small bones and teeth.”

His crew is a dedicated group: leaving their hotel rooms at 8am and working throughout the day—with a short break for lunch–until 5pm (or later if the weather holds). Ideally, there are nine crewmembers per season, but they have done it with less people. Digging has sometimes required breaking rock, so among the many tools used are sledgehammers and chisels.

ISM - Cave digging

 

[Digging for peccary bones, image courtesy of Ron Richards, the Indiana State Museum.]

 

Over the years, the cave rooms have gained descriptive names: the Peccary Room, for example, the X Room, and the Bat Room.

The “Microfauna Room” was named after the large amount of small bones they found when they began digging through the top layers of soil and rock. This is where the aforementioned Dire Wolf was discovered.

“Near the bottom of that room, down at the 25,000-yr level,” Ron explained, “we began to get fairly complete skeletons of things like Dire Wolf, Black Bear, an otter, a snowshoe hare, a lot of small shrews and mice.”

“We really believe that those animals fell in this pit. They dropped, and they went down about 15-20 feet. I think most of the time it was probably full of water.

“It’s just a lonely place to be. Whether they could stand at the bottom, I don’t know. But there’s no way out.

“There [was] enough mud washing in from the ceiling of that room that they were buried under real fine sediments. And that preserved them very well.”

Some of the fossils discovered have been both remarkable and rare. A tapir tooth—only the second to be found in the entire state of Indiana—was found in the cave. Several beautiful armadillo (Dasypus bellus) plates [osteoderms] have been discovered have been discovered (that is the actual name; ‘beautiful’ is not necessarily a description). Ron painted a picture of this by saying, “When one animal dies, there’s about 3,000 plates that disintegrate and go everywhere, like little dominoes.”

“Two years ago,” he said, describing the ‘Twilight Room’, “we started finding some articulated peccary skeletons.”

“Deep in the cave we didn’t find a lot of that. The bones would be disturbed, and you could just see sort of a jumbled mass that had been moved by water, by gravity, [or] by other animals.”

“In this room, we found things that were articulated, feet in place, all of the little toes in place. Really unusual.”

The earliest fossils found were parts of a giant land tortoise, a species that cannot live in cold climates. Finding this indicated that the area, at that time, did not freeze.

Also found were fossils of a pine marten, a species that, conversely, lives in Northern climates today.

And as for peccaries, Ron estimates that they have found the bones of approximately 650 individuals. They determined this number by by counting the total number of large, pointed canine teeth and dividing by four.

ISM - flat-headed peccary

[Bones & skull of the flat-headed peccary, image courtesy of Ron Richards, the Indiana State Museum.]

“So the question is then: did they live here? Or did they all have a misfortune and die here? It’s a little of both, but it’s mainly that they probably inhabited this cave and rock shelter for most of that time period.”

Ron mentioned that a number of the fossil discoveries in the cave are new to him.

So how does one identify unfamiliar fossils?

“We have a general reference collection of modern bones,” he replied, “and there is a big collection at Indiana University, Bloomington that I had become very familiar with in the 1970’s and 1980’s.”

He went on to explain that he referenced available literature and visited other museum collections.

“I had written correspondence,” he continued, “and the mailing of specimens with several experts in the eastern United States. My foremost ‘mentors’ were Dr. Russell Graham (then The Illinois State Museum), and the late Dr. J. Alan Holman (The Museum, Michigan State University), but I also had open correspondence with the late John E. Guilday (Carnegie Museum of Natural History), the late Dr. Paul W. Parmalee (The McClung Museum, University of Tennessee), Dr. Holmes Semken (University of Iowa) and the late Wm. R. Adams (Zooarchaeology Laboratory, Indiana University).”

“Everything [is] dug in square units,” he said. “We have thousands of these units. We can show the distribution and abundance of anything that pretty much died in that cave for thousands of years.”

And the work is hardly done. Ron estimates that the digging portion may be completed within the next 5 seasons (5 years), but the analysis of the immense amount of fossils has yet to begin.

“We’ve got probably 30 radiocarbon dates from the cave. Every year, we get one or two more.”

Ron explained that the cave has, so far, produced “probably 7,000 small plastic boxes of small bones, and 2,000-3000 larger containers of larger bones.”

“It’s my job to identify those. But, you understand,” he said, laughing, “life is short. I could spend all my time, day and night, just working with that alone. It’s an immense project.”

————–

Many, many thanks to Ron Richards, whose generosity astounds me.  I am profoundly grateful for his time, his patience with my “volley of questions” and his fascinating descriptions.  It is always a pleasure and an honor connecting with him!

A sincere thank you to Bruce Williams for prompting this post!

**The name and location of this cave were intentionally left out for security reasons.

Embed from Getty Images

[Image of the Indiana State Museum, Getty Images]

An Ice Age Wonderland – Yukon Paleontology, Part 3

In 2004, scientists in the Yukon discovered a rare and surprising remnant of the Pleistocene: an Ice Age meadow. And some of the grass, although at least 30,000 years old, was STILL GREEN.

Gold bottom turf_30,000 year old grass below ash

[Fossil grass below layer of tephra at Gold Bottom Creek, part of a 30,000-year-old grassy meadow discovered in 2004, from Ice Age Klondike, courtesy of the Government of Yukon. To see a picture of some of the green grass, please see page 33.]

 

In Ice Age Klondike, Dr. Grant Zazula and Dr. Duane Froese explain that this layer—at least 40 meters long–was buried by volcanic ash, or ‘tephra’.

 

30,000 year old bed of Dawson tephra

[The layer of tephra is the whitish colored portion toward the bottom; 30,000-year-old tephra, image courtesy of the Government of Yukon.]

 

Few places in the world offer us such a concentrated wealth of information about the Pleistocene, and the Yukon is one of them.

“There are a lot of common animals like woolly mammoths and bison and horses that we find all the time,” Dr. Zazula said. “But it’s really exciting when we find the bones or the fossils of the rare species, things like camels, or short-faced bears, or lions. Probably for every 500 bones we find, we might find one bone of a carnivore.”

Susan Hewitson in field with lion humerus

[Susan Hewitson holding an Ice Age lion humerus, courtesy of the Government of Yukon.]

lion mandible

[Ice Age lion mandible, courtesy of the Government of Yukon.]

“I think that one of the things that has really been exciting for me,” he offered, “is that, in the last 10 years, the field of ancient genetics has really taken off in terms of being able to extract DNA from Ice Age bones, then study the details of evolution and how these animals are related to one another.”

beth shapiro with horse jaw 2

[Geneticist Beth Shapiro examines a partial upper jaw bone of a Yukon horse emerging from the frozen mud at Quartz Creek, from Ice Age Klondike, courtesy of the Government of Yukon.]

 

fossil horse jaw

[Yukon horse jaw uncovered by placer miners on Quartz Creek near Dawson City, from Ice Age Mammals of Yukon, courtesy of the Government of Yukon.]

 

“[The Yukon is] one of the best places in the world to do that because of the bones being found in permafrost. [There are] so many Ice Age bones that are being found, and they’re really accessible.

“So we work really closely with the geneticists all the time; we’re working on all kinds of different projects together. It’s nice to be able to collaborate with a field like that and make fossils from the Yukon available for study.”

Geneticist Mathias Stiller - tusk - BonesnBugs.2010.TKuhn_082

[Geneticist Mathias Stiller with tusk found in the muck at Quartz Creek, courtesy of the Government of Yukon.]

This author writes from an area within the United States that is fossil-poor (finding one mastodon tooth is an enormous deal, and most years pass without a single reported fossil). In comparison, the amount of fossil bones found in the Yukon staggers the imagination. But that is not all that the Yukon has to offer.

Even those not generally interested in paleontology get excited when they see or hear about mummified Ice Age animals. There is something so much more dramatic, that much more intriguing, about seeing an extinct animal in the flesh.

Dr. Zazula was frank about being slightly envious of Siberia’s wealth in that domain. Outside of Blue Babe, a steppe bison carcass found in Alaska, the most spectacular mummified animals have been found on the other side of the world.

And yet, one cannot ignore that mummified remains—partial or otherwise—are also an exciting part of Yukon paleontology.

mummified ferret

[40,000-year-old mummified black-footed ferret discovered by the McDougall family’s dog, Molly, at their placer gold mine on the Sixtymile River, from Ice Age Klondike, courtesy of the Government of Yukon.]

 

One of the more remarkable finds was a partially mummified horse, discovered by Lee Olynyk and Ron Toews in a gold mine.

26,000 year old mummified Yukon horse (Equus lambei) foreleg recovered a....Canadian Museum of Nature

 

[26,000-year-old mummified horse (Equus lambeii) foreleg showing preserved hair, hide and muscle tissue, recovered at Last Chance Creek, Yukon, from Ice Age Mammals of Yukon, courtesy of the Canadian Museum of Nature.]

 

horse tail

[Image of mummified horse tail, courtesy of the Government of Yukon.]

 

Internal organs as well as a significant portion of the hide (with mane and hair!) were recovered. One can see this at the Yukon Beringia Interpretive Centre, the museum in the capital city of Whitehorse.

Embed from Getty Images

 

Also exciting, but from the neighboring Canadian Territory, was a discovery in the village of Tsiigehtchic. Dr. Zazula participated in uncovering this animal.

“[We excavated] a good portion of a carcass and a skeleton of a steppe bison, which turned out to be about 12,000 years old. There was still a bunch of hair and stomach and intestines and some of the limb bones were still articulated with muscle.”

He wrote about this in more depth with Dr. Beth Shapiro (image above) and several other colleagues in 2009. Not only remarkable for its level of preservation, this was also the first reported mammal soft tissue from the Pleistocene in “the glaciated regions of Northern Canada.

fossil steppe bison skull quartz creek

[Large fossil steppe bison skull found Quartz Creek, from Ice Age Klondike, courtesy of the Government of Yukon. Not the same bison fossil mentioned above.]

Then in 2010, Derek Turner and Brent Ward found the “oldest reliably dated” Western camel fossil found in what was once Eastern Beringia. As mentioned in previous posts, Beringia was the area that covered most of Siberia, Alaska and Yukon when the land was connected in the Pleistocene.

Derek Turner, Brent Ward and Dr. Zazula explain, in their paper about this discovery, that North America was once home to possibly six different species of camel. (There appears to be some dispute about whether six distinctly separate species existed.) And, contrary to what one might expect, Camelops—the camel genus—originated in Central Mexico.

ice age camel metatarsal (foot bone)

[Ice Age camel metatarsal (foot bone), courtesy of the Government of Yukon.]

For someone who has never participated in the excavation of either a mummified animal or fossils from permafrost, it was interesting to learn that there is a distinct smell when working with the muck.

Monitoring Dominion Crk (1)

[Placer gold mining monitor, Dominion Creek, courtesy of the Government of Yukon.]

“The only thing that’s kind of similar is the smell of a barnyard. But this is a barnyard from 30,000 years ago, and it’s from mammoths and horses and camels. All this rotten stuff that was [once] animals and plants that died a long, long time ago, frozen in the ground, and it’s now starting to thaw.”

The ever-growing research and discoveries from the Yukon paint a vivid picture of a by-gone era. It is, perhaps, the closest thing to a window into the Ice Age that we have.

When asked if there was anything that had not yet been found that he would be thrilled to find, Dr. Zazula didn’t hesitate: a woolly rhinoceros.

“We know that woolly rhinoceros are, so far, only found in Siberia,” he said, explaining why this would be so significant. “They extended all the way to the Bering Sea essentially, but they seem to never have crossed Beringia into North America. There is no fossil record of Ice Age rhinos here. But if they did [cross Beringia], that would be pretty amazing to find one of their fossils.”

Dinosaur enthusiasts, however, may be disappointed.

“In the Yukon, there’s almost no record of dinosaurs or Mesozoic fossils at all. I’ve been working with colleagues over the past handful of years, trying to find dinosaur deposits. But there’s no record of dinosaurs here except for a few handful of things. So, it’s not really [the place to be] if you’re interested in dinosaur paleontology. And that’s fine for me because then I don’t have to get involved in dinosaur work.”

“The Ice Age,” he continued, “is definitely what I’m interested in.”

Zazula with horse skull selfie

[Paleontologist Grant Zazula with Ice Age horse skull, discovered this past summer, courtesy of the Government of Yukon.]

Dr. Zazula began grad school in Alberta studying anthropology. Initially, he wanted to become an archaeologist. His undergrad studies focused on Arctic people and research. A strong theme, he explained, centered on the first humans to cross the land bridge into what is now North America.

“I found myself becoming more interested in the environments that those first peoples in North America were encountering,” he mused. “Instead of just trying to study the people themselves, [I wanted to understand] them in more of a wider geographic or environmental context. So, I switched gears during my grad school days from anthropology into biological sciences.”

After doing paleoecological work in the Old Crow region of the Yukon, Dr. Zazula was invited to join a group of researchers working in the Klondike.

“We started doing fieldwork at these gold mines, and we kept on running into these strange balls of hay frozen in the frozen mud, in the Ice Age sediments. And we didn’t really know what they were at first.”

So he contacted Dick Harington—a well-known paleontologist within Canada for his decades of work with fossils and gold miners in the Yukon. Dr. Harington thought they might be Arctic ground squirrel nests, and in further conversation, explained that they had not yet been a topic of study. In other words, not much was known about them.

25,000 year old fossil arctic ground squirrel nest at Quartz Creek, summer 2005 (photo by G. Zazula)

[Fossil nest of an Arctic ground squirrel, 30,000 years old, found at Quartz Creek in summer 2005, from Ice Age Klondike, courtesy of the Government of Yukon.]

“Over the first summer of fieldwork, I think I collected almost a hundred of these ground squirrel nests. And what was really cool about it is that the group that I was working with specialized in glacial stratigraphy [and] using volcanic ash beds to date sediments.

“Because they knew the age of these different volcanic ash layers that are found in the sediment, we could actually place these ground squirrel nests in different points in time in the past. We were able to develop sort of a time series of these Arctic ground squirrel nests.

“[Over] the next four years, I picked apart Arctic ground squirrel nests that [dated] between 20,000 and 80,000 years old or so.”

 Nest with squirrel skull

 

[Arctic ground squirrel nest, courtesy of the Government of Yukon.]

These nests are also known as “middens.” In his paper on the topic, Dr. Zazula and his colleagues describe these underground Ice Age homes. What these middens revealed, not just about these specific Ice Age animals, but about the Pleistocene environment at the time, is incredible.

Contained within these middens were ‘caches’ of food—seeds and plants from the area. These tiny plants give scientists a much better understanding of the climate and environment thousands of years ago.

squirrel nest - quartz creek

[Arctic ground squirrel nest, courtesy of the Government of Yukon.]

 

squirrelnest - cache

 

[Arctic ground squirrel nest, cache highlighted by author, per the paper on this subject.]

 

“I think we’ve identified over 60 different plant species in them, and I wasn’t expecting that at all.”

In addition—and much to this author’s surprise–they found fossil insects, including beetles.

“Fossil Pleistocene beetle remains are actually quite common in sediments,” he said. “And they’re actually pretty useful for climatic reconstructions, because most beetles have a very narrow temperature or climatic envelope that they can live within.”

Squirrel nest - DawsonFieldwork_2011_TKuhn_254

 

[Arctic ground squirrel nest, courtesy of the Government of Yukon. Can you find the squirrel skull?]

 

Embed from Getty Images

[Extant Arctic Ground Squirrel (Spermophilus parryii) hibernating in burrow, Fairbanks, Alaska; Getty Images]

 

In all of Dr. Zazula’s papers, one can see scientists from a variety of fields as co-authors or in the acknowledgements for their help with research. This was reiterated in our phone conversation: he is uniquely positioned as Yukon paleontologist to provide Ice Age material for a wide-range of study to a wide-range of fields.

“Especially with the Pleistocene,” he explained, “there are so many interconnected aspects of research. You need to have a geologist around. And then, in terms of putting the big picture together, you want to have someone that can reconstruct plant fossils. If you’re just doing it alone, you wouldn’t get much of the [big] picture anyway.

“So we’ve really kind of developed this way of doing things as a team.”

Morehouse, Zazula and Stiller

[Archaeologist Jana Morehouse, Paleontologist Grant Zazula and Geneticist Mathias Stiller, image courtesy of the Government of Yukon.]

“To me, it’s all so interconnected: the geology, the ecology and the mammals and then the archaeology. You might as well work together to try to accomplish goals, and that’s how we’ve done it. It’s been pretty successful.”

“And,” he added, “it’s a lot more fun that way anyway.”

Beth Shapiro_withHorse

[Geneticist Beth Shapiro with Ice Age horse jaw, image courtesy of the Government of Yukon.]

“Prior to the Yukon government establishing the paleontology program, all of the fossils that were being collected went back to Ottawa for the National collection and the National Museum. So most of the material that has ever been collected from the Yukon is actually not here. It’s in Ottawa.

“The Yukon government decided in the mid ‘90’s that they would like to establish its own program in Arctic archaeology and paleontology. Since that time, fossils collected here, stay here. And the position [of Yukon paleontologist] was created to oversee that.”

It’s a position he’s held for the past eight years, and one can hear his genuine enthusiasm for it in his voice.

“It’s a great job,” he stated. “Sometimes I’m shocked that I get paid to do this. It’s pretty exciting.”

Over the years, Dr. Zazula has been featured in some of the most prominent global media. Some of those include NPR, the CBC, the NY Times, and the National Post. This past summer, he was filmed with paleontologist Dick Mol from the Netherlands by a German documentary team. That documentary has been aired in Europe since this past December.

Dick Mol and Grant Zazula - Yukon

[Paleontologists Grant Zazula and Dick Mol, photographed by Florian Breier, the director of the German documentary; image courtesy of Dick Mol.]

Not everyone, regardless of their profession, is as comfortable with media or journalists.

“I think there are a lot of people that stay in labs and put their heads down and don’t really interact with the media, but I think it’s really important,” he said.

[I]t’s one thing that’s never taught: how to conduct interviews or how to take your scientific work and present it or make it relevant to the public. And I think that’s a real problem, because if you are a practicing scientist after graduate school, you’re undoubtedly going to do research that attracts interest, and if you don’t have the ability to speak about it or to present it, you lose a lot of traction. In a lot of regards, science is kind of a big competition. It’s like a big science fair. If you don’t produce results and attract attention, you won’t continue to be funded. You can be an excellent scientist and sort of fade away if you don’t have the ability to attract people’s attention.

“I work for [the] government, where we’re publically funded by tax dollars. [F]or some people, [paleontology] might not seem very relevant for society. Still, I think it’s pretty important whenever we have something new to talk about, in terms of new results or new and interesting things, we should make sure it gets out to the public through media.

“Politicians are the people that decide if these programs continue to be funded. And if they see that there’s a lot of media interest and a lot of people learning because of it, then they’ll definitely keep funding these kinds of programs. And I’m grateful that they continue to do so.”

paleoecologist Rolf Mathewes from Simon Fraser University_bison jaw and mammoth tooth

[Paleoecologist Rolf Mathewes from Simon Fraser University,courtesy of the Government of Yukon. Can you pick out the mammoth tooth?]

Explaining the reasons for his fascination with the Ice Age, Dr. Zazula said, “Dinosaur paleontology doesn’t really tell us much about the modern environment. If we’re interested in what we have today and how it’s changing because of, say, climate change, or environmental change, we’re not going to get much information about environmental processes by studying dinosaurs.

The study of the Ice Age, [however], is how the modern world came to be.

“When you think of tens or hundreds of thousands of years ago, it may seem like a long time ago, [but] it’s just a geological instant. And in that short time period–in that geological instant–the changes that have happened to result in what we have here today are amazing!

“To think of giant elephants and lions running around North America: it’s such a different world. And yet so many aspects of that world can inform us of what we’re dealing with today.”

sixtymile mammoth 1

[Image of mammoth skull found by Hawk Mining along the Sixtymile River, courtesy of the Government of Yukon.]

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——————–

This trilogy of posts on the Yukon–with all of the beautiful images and the fascinating information they contain–could not have been possible without the generosity of Dr. Grant Zazula.  He is an adept and engaging speaker; the Yukon is incredibly lucky to have him at the helm of the paleontology program!  Once again, and with great sincerity, a Mammuthus columbi-sized THANK YOU to him.

This trilogy would not have occurred without the great generosity and wonderful thoughtfulness of Dick Mol, who is a wonderful, wonderful person.  With great sincerity, I wish him, too, a Mammuthus columbi-sized THANK YOU!

——————–

If you haven’t already checked out these publications by Grant Zazula, Duane Frose and Tyler Kuhn, please do! They are available online:

Other articles referenced:

 

Yukon Paleontology Program: http://www.tc.gov.yk.ca/palaeontology.html

Yukon Beringia Interpretive Centre: http://www.beringia.com/index.html

Terra X – German Documentary: Mammuts – Stars der Eiszeit, http://www.zdf.de/terra-x/mammuts-ikonen-der-eiszeit-35507636.html

The Treasure in Gold Mines: Fossils! – Yukon Paleontology, Part 2

I admit to having preconceived notions of what it means to find fossils and to mine for gold.  It never occurred to me that these two occupations might be interconnected.  Nor would I have ever described the image below as what it actually is: placer gold mining.

Placer Gold Mining - Monitor

 [image of a water monitor, placer gold mine in Quartz Creek, courtesy of the Government of Yukon. Can you find the rainbow?]

That water jet is called a ‘monitor’, and it slowly melts the permafrost, exposing the alluvial gold from the gravel below.

It also reveals fossils.

“Since the beginning of the Gold Rush, people have been finding Ice Age fossils there,” explained Dr. Grant Zazula by phone.

The Gold Rush, an event that peaked in 1898, brought people from all over the world to the Klondike area of the Yukon.  It was once solely the home of several indigenous cultures, including the Inuit, Han, Tagish, Tlingit and Tutchone. But the hope of finding treasure—in an industry that required inexpensive equipment (a pan, a rock pick)—brought thousands to an area that most would consider inhospitable.

 

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gold miner Gerry Anhert

[image of gold miner, Gerry Ahnert, courtesy of the Government of Yukon]

One of the techniques used to find gold at that time was borrowed from California mining: water monitors.  Monitors were also relatively inexpensive and highly effective.

Back then, as now, these monitors revealed not only gold, but a wealth of fossils.

Assistant Palaeontologist Elizabeth Hall organizing a days collection of bones in the tent at our field camp near Dawson city

[image of Paleontologist Elizabeth Hall organizing a day’s collection of bones at the field camp near Dawson City, courtesy of the Government of Yukon]

“I’m always pretty fascinated by these stories immediately post-Gold Rush of people finding mammoth skulls,” said Dr. Zazula.

One can see a number of black-and-white images of these and other fossil finds in Ice Age Klondike, written by Dr. Zazula and Duane Froese.  Finds such as this prompted museums to send representatives out to the region to bring back fossils for their collections. One such expedition in 1907 and 1908 is detailed in the Bulletin of the American Museum of Natural History in NY.

“Without the gold mining, these fossils would never be found,” Dr. Zazula continued, referring to today’s fossil discoveries. “They’re using heavy equipment and other types of equipment to move this frozen ground because [it] is essentially locked in permafrost that wouldn’t be accessible without the gold mining.”

Upper section

Looking upstream at 2011 stripping operation

Unsampled tehpra (inaccessible) visible in wall of monitoring drain

TK-11-03TK-11-06

QCreek mine - LOVE THIS - monitor and permafrost - DawsonFieldwork_2011_TKuhn_029

 [images of gold mines near Dawson City, courtesy of the Government of Yukon]

Melting the frozen ground with these jets isn’t as damaging to fossils as one might imagine. Dr. Zazula described a process in which fossils are slowly removed from the heights of the muck—the frozen silt—and slide down into the valleys below.  When remarkable fossils are seen by paleontologists, the miners always accommodate them, enabling Dr. Zazula and his colleagues to excavate them manually.

Arctic Ground Squirrel fossil skull

 [fossil Arctic Ground Squirrel skull emerging from the muck, image courtesy of the Government of Yukon]

Zazula sampling squirrel nest

[Dr. Grant Zazula sampling frozen sediment along a vast wall of muck at Quartz Creek, courtesy of the Government of Yukon]

 

It’s an incredible partnership, one that began in the 1960’s with Dr. Richard Harington of the Canadian Museum of Nature. Dr. Harington made annual summer trips to visit the miners and discuss their fossil finds.  It is a tradition that Dr. Zazula and the other two Yukon paleontologists before him have maintained.

But consider the expanse of the Yukon Territory.

Land near Dawson City

[image of land near Dawson City, courtesy of the Government of Yukon]

And consider that, as Dr. Zazula stated, “[t]here are 100 active gold mines, give or take a few dozen here or there. And virtually all of them produce Ice Age fossils.  So in a summer, we can collect 5,000 specimens. There’s a lot of material coming out of the ground, and we’re trying to recover it as much of it as we can. It’s almost industrial-scale paleontology.”

This gave me pause: one Yukon paleontologist in the entire Territory, who—in addition to keeping in touch with about 100 mines in the Klondike—is responsible for all of the other fossil discoveries and research of the area.

“Prior to 3 years ago, it was really a one-person operation and that was me,” he admitted.

With the acquisition of funds, however, Dr. Zazula now has two assistants in the field: Elizabeth Hall and Susan Hewitson.

Elizabeth, Dick, and Susan with fossil Bootherium skull

[image of Elizabeth Hall, Dick Mol holding a fossil Bootherium skull, and Susan Hewitson, courtesy of the Government of Yukon]

They have established a field camp near Dawson City in close proximity to the gold mines. This enables them to be in daily contact with the miners in the short mining season—the end of May through October.  Dr. Zazula described this work as driving on back roads to the various mines, getting to know the miners and collecting the fossils released from the permafrost.

Elizabeth Hall recording a collection of bones at a gold mine

 

[image of Elizabeth Hall recording bones at a gold mine, courtesy of the Government of Yukon]

“Since we’ve done that, our collection has just exploded in terms of the quantity of material that we’re finding.  But it also really establishes and strengthens the relationships that we have made with the gold miners as well.”

Dawson City

 [Dawson City, the previous capital of the Yukon Territory until 1953; At the height of the Gold Rush, this town consisted of numerous wooden buildings and a sea of canvas tents behind them; image courtesy of the Government of Yukon]

“[The] program really hinges on [these] two people,” Dr. Zazula wrote. “Elizabeth Hall oversees most of the field work in the Klondike and is the collections manager, and Susan Hewitson [is] a field technician in the summer months.

“They do most of the work to collect the fossils, clean the fossils, identify the fossils, catalog the fossils and organize the database. This really frees up my time to write, do research and other outreach work.”

Elizabeth Hall holding baby mammoth

[image of Elizabeth Hall holding a baby mammoth tooth, courtesy of the Government of Yukon]

Elizabeth, Susan and her husband Alex collecting bones in 2012

[image of Elizabeth Hall, Susan Hewitson and her husband collecting fossils, courtesy of the Government of Yukon]

 

“Elizabeth started her as a summer student assistant about 10 years ago, and we finally created a full time position for her 3 years ago. We were also students together at Simon Fraser University. She is in the middle of completing a masters degree in Earth and Atmospheric Sciences at University of Alberta; her thesis work is on fossil microtine rodents from Old Crow, Yukon.”

Elizabeth Hall in field

[image of Elizabeth Hall, courtesy of the Government of Yukon]

“When it’s good for gold, it’s a good time to be an Ice Age paleontologist in the Yukon because there’s so much material that’s coming out of the ground.”

Tyler Kuhn

 [Paleontologist Tyler Kuhn with a mammoth tusk found at a placer mine in Dawson City, Yukon; courtesy of the Government of Yukon]

 

Again, an enormous thank you to Dr. Grant Zazula for his fascinating insight and most generous time.  

Thank you, again, to Dick Mol.  

And thank you to all of the gold miners who enable Dr. Zazula, Elizabeth Hall and Susan Hewitson to conduct their research and collect fossils!!

Dick Mol and Grant Zazula - Yukon

[image of Grant Zazula and Dick Mol, holding a steppe bison skull; taken by Florian Breier, courtesy of Dick Mol]

———————

Yukon Paleontology Program: http://www.tc.gov.yk.ca/palaeontology.html

Yukon Beringia Interpretive Centre: http://www.beringia.com/

Publications and articles referenced:

Exciting New Info About Mastodons and Humans – Yukon Paleontology, Part 1

“Good morning!”

It’s not just a greeting; it sounds like a proclamation.

The voice on the other end of the phone is deep, melodic, and—as our conversation progresses—punctuated with moments of laughter.  We have been discussing paleontology in the Yukon, and with each new detail, I begin to wonder why this territory is not making regular international headlines.

Dr. Grant Zazula’s work is fascinating, and it is neither a short phone call nor the only communication we’ve exchanged. And yet, it is all that I can do not to encourage him to keep going, long after social decorum dictates that he has been more than generous with his time.

Dr. Zazula and mastodon leg

[image of Dr. Grant Zazula with a mastodon ulna, part of the Earl Bennett mastodon, courtesy of the Government of Yukon]

Dr. Zazula is the Yukon paleontologist, a job that has only existed since 1996. His own tenure began in 2006.  With an office in Whitehorse, the capital of the territory, his work oversees an expanse of Canada that abuts Alaska.  It is a land of dramatic beauty, where colors dance in the sky and mountains tower in silent grandeur.

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His most recent paper, co-written with 14 other people, made news throughout the world and continues to attract media attention. In it, the scientists present data that completely overturns previously believed information about extinct animals and the impact that humans may or may not have had upon their survival.

“[T]here were two radiocarbon dates in the literature from Yukon mastodons,” he explained in an email. “One that was ~18,000 and the other 24,000 years old.”

“Based on analysis of the paleoecology, that was a time when steppe-tundra grasslands covered Alaska, Yukon and Beringia. There were probably no trees, few shrubs and almost no standing water. It was very cold and, especially, dry. This seemingly is not good mastodon habitat. So either the dates were incorrect, or our understanding of mastodon ecology, behavior and adaptations need[s] to be revised.”

Various species of mastodon once existed throughout the world.  Although their fossils look elephantine, they are not believed to be direct ancestors of today’s elephants. They are, however, part of the same umbrella mammalian group: the Proboscidea (so-named for the trunks possessed by many—but not all–of their members).  In North America, that group contained the American mastodon (Mammut americanum), the woolly mammoth (Mammuthus primigenius), and the Columbian mammoth (Mammuthus columbi).

Cohoes mastodon

 [image of the Cohoes mastodon, NY State Museum, Albany; taken by the author]

Mastodons tended to have straighter tusks and were shorter than their mammoth cousins. They also ate hardier vegetation, food that required a much different tooth structure than mammoths.

ISM - Mastodon tooth

[image of mastodon tooth, courtesy of the Indiana State Museum]

ISM - Mammoth tooth

[image of mammoth tooth, courtesy of the Indiana State Museum; for more info about the differences between mammoths and mastodons, see this post.]

Parts of Siberia, Alaska and the Yukon were once connected in an area known as “Beringia.”  The Bering Strait did not yet exist, enabling animals and eventually the first humans to cross into our continent.  It is believed that humans arrived in what is now North America about 14,000 years ago.

And this is where the research of Dr. Zazula and his colleagues becomes particularly important.

Prior to their paper, one theory to mastodon extinction laid the blame upon first humans: it was proposed that they overhunted these animals.

Sampling 36 fossils and presenting 53 new radiocarbon dates, Dr. Zazula and his colleagues found that mastodons within Alaska and the Yukon were much, much older than the originally published dates.  In other words, their research suggests that mastodons from what was once Eastern Beringia were no longer present when the first humans appeared.

The path to this remarkable research did not happen overnight.

The foundation appears to have been laid by two different events: by the chance meeting of Dr. Zazula and a gold miner, and later, by the PhD work of a graduate student.

If one reads the acknowledgements on the aforementioned paper, Dr. Zazula references Earl Bennett as both the donor of a partial mastodon skeleton and his inspiration to learn more about mastodons within the Yukon.

“Earl is a great Yukoner,” Dr. Zazula wrote when asked about this. “He mined for gold underground in the winters with a pick and shovel, decades ago. He worked on big gold dredge machines. And, he loves paleontology.

“While mining, he made collections of Ice Age bones that were just left around the mining camp or were encountered while mining. He eventually amassed an amazing collection.

“In the early 1970’s a gold dredge on Bonanza Creek hit a skeleton of a mastodon. An incredibly rare find! Someone collected it and was looking to sell it. So, Earl bought the skeleton just to make sure that it never left the Yukon. He had it in his garage for decades.

“One day a mutual friend introduced me to him in a coffee shop, about a year after starting my job [as the Yukon paleontologist]. He said that he had a mastodon skeleton and wanted me to see it. I ‘corrected’ him, saying that it was more likely a mammoth, because we almost never find mastodons in the Yukon. He assured me he know the difference and said he would see me tomorrow at my office.

“The next day he backed his truck up and in it was a partial mastodon skeleton. I couldn’t believe it. There were several postcranial bones, some vertebra, scapula, parts of the skull and parts of the mandible with teeth. It was amazing. I wanted to find out how old it was, and that was one of the inspirations for this project. Earl is a good friend now and big supporter of our research.”

Bennett mastodon skeleton

[Paleontologist Grant Zazula with a partial American mastodon (Mammut Americanum) skeleton found on Bonanza Creek and donated to the Yukon fossil collection by Earl Bennett, from Ice Age Klondike, courtesy of the Government of Yukon]

That partial skeleton was indeed one of the many fossils sampled for the paper.

Dr. Jessica Metcalfe, one of the co-authors, also prompted this research when conducting work for her PhD.

“[S]he was doing a project looking at stable isotope ecology of mammoths and mastodons in various places in North America,” said Dr. Zazula.

Jessica Metcalfe with mammoth bone

[image of Dr. Jessica Metcalfe with mammoth bone, courtesy of the Government of Yukon]

Her work included Yukon fossils that were sent to the lab at the University of Arizona to be radiocarbon dated.   Those dates turned out to be older then 50,000 years old.

“So that’s what got me thinking,” he continued, “‘well, maybe those original published dates are wrong.’”

“The first step was to re-date [the specimens that had produced the original published dates]. The new dates turned out to be >50,000 years. So we knew there was a problem with the previous dates. We figured then we should date as many as we could get our hands on.”

This lead Dr. Zazula to connect with Dr. Ross McPhee, another co-author.

“I got in touch with him early because he oversees collections at the American Museum of Natural History, [and] he has a big interest and lots of experience working on Ice Age extinctions. [H]e’s an excellent writer and really kind of kept us going with some of the writings. He was really integral to keeping things together.”

The paper eventually involved a total of 15 people.

“I feel pretty strongly that if you worked on it and contributed to it, then you should be considered an author,” Dr. Zazula stated.  “So it ended up being a long list.”

One of the first aspects their paper addresses is the reason behind why the original published dates are incorrect: the dating analyses were contaminated by fossil conservation methods.

“Humic acids in soils can be absorbed by the bones and teeth and chemically bind themselves to the collagen,” he wrote, explaining further. “So, modern ‘young’ carbon in those acids basically contaminates the ‘old’ collagen in the ancient fossil. And, it can be tricky to remove.

“The same with consolidants in museums. Varnish, glue, and other substances to preserve fossils can be absorbed into the bone and chemically bind with the collagen in the bone. These substances probably contain young, modern carbon which messes up the radiocarbon dating measurements.”

When asked whether museums continue to use the same preservation products that contaminated the dates, he wrote, “Yes, for sure. The thing is now museums keep better records of what they use. Many of the fossils we dated were collected in the 1940’s or at least several decades ago. Museums were not that vigilant about keeping detailed records on those things then. Also, they seemed to put preservatives on everything. Now, at least if we know what was put on it, the chemistry can by developed to remove it. Most of the common preservatives now are soluble in alcohol or acetone and can be dealt with. The problem is when they are unknown.”

We discussed this further by phone.

“One thing about Alaska and the Yukon,” he said, “is that the Ice Age bones that come out of the ground are so well preserved because of the permafrost. In other localities, say, the deserts of the American Southwest or the Great Basin or the Plains, where bones have been out in the sun and [are] dry and hot, they [sometimes] fall apart really easily when they come out of the ground. They need to be glued and consolidated with these various types of museum products.

“So you kind of have to weigh the different values.

“Say if it’s a specimen that’s already been radiocarbon dated, and it starts to slowly disintegrate, well, then you kind of have to intervene or else you’re just going to end up with a box of dust and broken bone. You have to decide whether the importance is more with display or preservation of the morphology versus needing to radiocarbon date or other types of analysis.

“[Y]ou have to look at the pro’s and con’s of whether the sampling [for radiocarbon dating] will ruin the specimen or not, and what is the potential information that can be gained by doing it. To me, I feel that having a research collection [in the Yukon], it’s all about research and learning new things from these specimens.”

Ultimately, I wondered whether Dr. Zazula expected the results he and his colleagues uncovered.

“I wasn’t quite sure,” he answered. “I had the gut feeling that these previously published radiocarbon dates were probably wrong. It didn’t make a lot of sense ecologically to have mastodons living in the far North when it was seemingly habitat they couldn’t live in: habitat with grassland and cold, dry steppe tundra conditions, no trees and very few shrubs.

“But there [was] also a part in the back of my mind that thought, ‘well, if those [previously published dates] were right, that’s maybe even more interesting because they are telling us something about mastodons and their behavior and their adaptations that we didn’t know before.’”

————

It was a great honor and pleasure to connect with Dr. Grant Zazula! Not only patient with my myriad questions, he is an adept and fascinating ambassador for the Yukon. A Mammuthus columbi-sized thank you to him!

A Mammuthus columbi-sized thank you to Dick Mol, as well, who is the reason behind this post!

Dick Mol with horse skull

[image of Dick Mol with fossil horse skull, found near Dawson City, Yukon; courtesy of the Government of Yukon]

Yukon Paleontology Program: http://www.tc.gov.yk.ca/palaeontology.html

Articles and publication referenced:

 

Listen to Dr. Zazula discuss his paper on the CBC’s Quirks & Quarks: http://www.cbc.ca/radio/quirks/quirks-quarks-for-dec-6-2014-1.2864605/mastodons-made-an-early-exit-from-the-north-1.2864634