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?


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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!




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,, 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.

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[Image of the Indiana State Museum, Getty Images]