Dr. Advait Jukar – Solving Mysteries in South Asian Fossil Communities

Dr. Advait Jukar–Deep Time – Peter Buck Fellow at the Smithsonian Institute–wants to really understand ancient ecosystems in South Asia, but doing so means beginning with some of the very basics. Challenges include not just a lack of available fossils from the region, but also the lack of detailed records from early paleontologists and a dearth of contemporary research.

He is, in a sense, an explorer.  (All paleontologists are.)  If we think of paleontology as a sculpture in progress, many scientists are working on the fine details.  Dr. Jukar, on the other hand, has the clay and the tools, but the sculpture itself hasn’t even begun to take form.

Consider what he has to work with: isolated proboscidean teeth and skulls, for example, collected by Hugh Falconer and his crew in the early 1800s.  They didn’t record where the bones were found, let alone where each fossil was in relation to the other.  Those who later described these fossils made dubious claims regarding the species.  And few people to this day have revisited this data or expanded upon it. 

 

Image of Dr. Advait Jukar at work with an Elephas hysudricus molar; courtesy of Dr. Jukar

 

Compare this to Maiasaura fossils in the Northwest US.  So many fossils of this species have been excavated that Dr. Holly Woodward Ballard has created the Maiasaura Life History Project.  Its goal is to uncover more details about this particular species than any other currently known extinct creature.  She has a wealth of data at her disposal. Unlike Dr. Jukar, the fossils she can study have been found fairly well articulated, very well documented, and in remarkable abundance.  There are adults, sub-adults, juveniles and embryos.  She and her colleagues are able to add to existing scientific literature using the latest technology.  It’s an exciting project with absolutely fascinating possibilities.

 

FIGURE 6. Survivorship curve for Maiasaura. Sample size of 50 tibiae was standardized to an initial cohort of 1000 individuals (assumes 0% neonate mortality). Survivorship is based on the number of individuals surviving to reach age x (the end of the growth hiatus marked by LAG x). Age at death for individuals over 1 year old was determined by the number of LAGs plus growth marks within the EFS, when present. Error bars represent 95% confidence interval. Mean annual mortality rates (μ^) given for age ranges 0–1 years, 2–8 years, and 9–15 years. Vertical gray bars visually separate the three mortality rate age ranges; courtesy Dr. Woodward Ballard for this post

 

 

 

But so, too, is Dr. Jukar’s intended research.   Focusing on the tail end of the Neogene, about 4 million years ago, through the Quaternary, he wants to understand herbivorous mammals—their community, their ecology, their biogeography.  It’s just a question of building the necessary foundation first.

“I started to compile all of these species lists,” he explained by phone, “and saw that there were lots of species of proboscideans in South Asia during that period of time.  We have gomphotheres; we have stegodons; we have elephants.”

One way to understand an animal’s impact on its environment is to assess its body mass.  How big (or small) were these animals?  And therefore, how much did they need to eat?  A larger animal would presumably need to eat a larger amount of vegetation.  Similarly, a larger animal might reproduce less frequently than smaller animals.  Body mass reveals clues about how an animal fits into the ecosystem.

However, he continued, “I hit a wall because there was no way for me to estimate how big these elephants were.  The problem was they were largely known either from skulls or teeth, and the traditional methods to estimate the weight of an extinct elephant were using shoulder height or the length and circumference of the long bones. So if I have a skull but I don’t have long bones, I’m sort of in a bind, because now I can’t estimate how much this animal weighed when it was alive.”

He looked to methods that others have used in the past. One method used by his colleagues at Howard University seemed to be a promising fit.  They used the occipital condyle breadth of seacows—a proboscidean relative–as an indicator for body mass.  Dr. Jukar’s PhD advisor, Mark Uhen, mentioned that this method had also been used on yet another large mammal: the whale. 

The occipital condyle is a bone found at the base of the back of the skull, connecting the skull to the spinal column.  It’s a relatively small bone.  Why would this have an impact on determining body mass?

“If occipital condyle breadth is correlated with the size of the animal,” Dr. Jukar said, “and if the occipital condyle is the point where the skull attaches to the rest of the skeleton, then maybe the size of the skull scales with the size of the overall body. And if that’s true, then maybe the occipital condyle breadth will scale with the size of the limb bones as well.”

 

Image of the back of a mastodon (nicknamed ‘Max’) skull at the Western Science Center in California displaying the occipital condyle bone resting on the metal stand; photo taken by Jeanne Timmons

 

In other words, if a paleontologist has but one skull of an extinct proboscidean and no other related fossils, can that person measure the breadth of the occipital condyle as a way to determine the size and weight of that animal?

To test this theory on proboscideans, he researched available scientific literature and visited a number of museum collections.  Ultimately, he and his two co-authors, S. Kathleen Lyons and Mark Uhen, compared the occipital condyle breadth to the length and circumference of leg bones within extant elephants and extinct relatives.  Two elephant species were studied, as were six gomphotheres, three mastodons and one stegodon.  

Image of a fossil Moeritherium at the Yale Peabody Museum; photo taken by Jeanne Timmons

 

While careful to note that this method has its limitations, the results were promising.  The equations are different for each proboscidean family (gomphothere body structure and size is not the same as that of a mastodon) and they do not work for some of the smaller proboscidean species, such as Moeritherium.  In layperson’s terms, this research works for taller, lumbering proboscideans, not those with much shorter limbs and a perhaps waddling gait. Their paper and its results were published in the Zoological Journal of the Linnean Society: A cranial correlate of body mass in proboscideans.

This, though, is just the tip of the iceberg in terms of Dr. Jukar’s research.  An enormous collection of fossils from India resides in the Natural History Museum of London.  Found in an area referred to as the Siwalik Hills (or the “Siwaliks”) at the base of the Himalayas, Scottish paleontologist Hugh Falconer and his team collected them in the 1800s.  Among them are several stegodon teeth and skulls. 

Image of Dr. Advait Jukar measuring a Stegodon ganesa fossil in the Natural History Museum of London collection; courtesy of Dr. Jukar

 

The two species of stegodon excavated from the Siwaliks are, to this date, known as Stegodon insignis and Stegodon ganesa.  The species have very similar teeth, but their skulls seem to differ greatly.  The skull of S. insignis, according to Dr. Jukar, is “almost triangular in shape with relatively small tusks,” which Falconer chalked up to sexual dimorphism.

“Which I just thought was the weirdest thing to ever say about stegodons because the skulls are clearly different. They’re clearly not sexually dimorphic.”

Moreover, there seems to be confusion regarding which fossils Falconer assigned to which stegodon species that continues to this day.  

“So what was going on in his mind? I have no idea.  It’s a problem! Because since then, people have said that both of these must be the same species without really truly investigating them. 

“Any Stegodon tooth that they’re finding in the Siwaliks, they’re calling Stegodon insignis or Stegodon ganesa or a hyphenated version of the two: Stegodon insignis-ganesa, which is taxonomic heresy.” 

And here Dr. Jukar was emphatic: “You CANNOT do that with the taxonomic code.”

“And that was Osborn’s fault.”

He was referring to Henry Fairfield Osborn, former professor then curator of the American Museum of Natural History in the late 1800s.

“Osborn [is known to have asserted], ‘I agree with what Falconer said, so I’m going to hyphenate these two words.’  Which created such a mess.  So we have no idea what’s going on there. 

“There’s a lot of work to be done with elephant taxonomy, biogeography and systematics and comparisons between China, the Levant, East Africa and India.”

 

Image of the Levant (Public Domain)

 

Dr. Jukar and other colleagues have also recently published papers on the earliest known fossil of Hexaprotodon, an extinct hippo, from South Asia, and the first record of a Hippaprionine horse (Plesiohipparion huangheense) from the Indian Pliocene.

He is currently working with Dr. Adrian Lister of the Natural History Museum in London to further understand the various proboscidean fossils in the Siwalik collection.

This is important work, but Dr. Jukar pondered its reception to the wider world.

“For a long time paleontologists have been criticized as being mere stamp collectors because we find things and then we name them and then we try to figure out in what larger group they belong to.  But that is the basis of our data.

“Only when I have a comprehensive sense of what the species are, when they lived and where they lived can I start doing these more complicated community-level analyses.

“But because the basic science of naming a fossil might not be very exciting, [as it doesn’t directly impact] human life very much, it doesn’t get a lot of attention. 

“I am definitely interested in the big picture questions of dispersal from Africa into South Asia, about the ecology of these groups, about how communities have changed through time, but I can’t really do a rigorous analysis until I figure out who the [basic] players are in this place.”

Image of Dr. Advait Jukar with a Mammuthus columbi (Columbian mammoth) skull; courtesy of Dr. Jukar

 

References:

  1. Colbert E. (1996). Henry Fairfield Osborn and the Proboscidea. In:  Shoshani J, Tassy P. The Proboscidea : evolution and palaeoecology of elephants and their relatives, Oxford: Oxford University Press, xxii – xxv
  2. Dr. Advait Jukar’s website: https://advaitjukar.weebly.com
  3. Jukar, Advait M., Lyons, S. Kathleen, Uhen, Mark D. (2018.  A cranial correlate of body mass in proboscideansZoological Journal of the Linnean Society, Volume 184, Issue 3, 20 October 2018, Pages 919–931, https://doi.org/10.1093/zoolinnean/zlx108
  4. Jukar, Advait M., Patnaik, Rajeev, Chauhan, Parth R., Li, Hong-Chun, Lin, Jih-Pai (2019). The youngest occurrence of Hexaprotodon Falconer and Cautley, 1836 (Hippopotamidae, Mammalia) from South Asia with a discussion on its extinction, Quaternary International, January 2019, https://doi.org/10.1016/j.quaint.2019.01.005
  5. Jukar, Advait Mahesh, Sun, Boyang, Bernor, Raymond Louis, (2018). The first occurrence of Plesiohipparion huangheense (Qiu, Huang & Guo, 1987) (Equidae, Hipparionini) from the late Pliocene of India,  Bollettino della Società Paleontologica Italiana; 57(2):125-132 · August 2018
  6. Saegusa H. (1996). Stegodontidae: Evolutionary Relationships. In:  Shoshani J, Tassy P. The Proboscidea : evolution and palaeoecology of elephants and their relatives, Oxford: Oxford University Press, xxii – xxv

 

It was a GREAT pleasure and honor speaking with Dr. Advait Jukar.  Many, many thanks for your time, Advait, your help, your fascinating insight and your gorgeous images!! I cannot wait to read your future scientific papers!

 

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