Meet Henry Sharpe – Paleoartist, Future Paleontologist

In one painting, a Daspletosaurus is rubbing its snout against tree bark as a way to clean its skin after eating.  In another, a small velicoraptor simply investigates a much larger hadrosauroid (Plesiohadros djadokhtaensis).  Henry Sharpe focuses his artistic lens a little differently than other paleoartists might; shifting the view from one of naked aggression and survival to one of (potential) everyday moments in prehistoric existence.

These moments, often gentle–evocative of the behavior of extant animals, behavior we may readily recognize and understand—and absent drama, make his artwork perhaps that much more realistic.


Screenshots of artwork by Henry Sharpe from his website

He bases them all on the latest research, keeping up with the most current scientific papers.  He also extrapolates known behavior of creatures alive today and applies it to similar extinct animals, an educated guess rather than a flight of pure imaginative fancy.  And in that way, he prompts the viewer to think and question: could this be how that animal truly behaved?  Is this how a snapshot in time might have looked at that moment for those animals?  How much do we know about that animal?  What else do we have yet to discover?

Or such are the thoughts that any good paleoart encourages within me. Good paleoart—in my opinion—invites more questions, inspires more interest, encourages more research.  Because that art opens doors that I didn’t realize were there. It offers a tantalizing glimpse of animals many of us yearn so deeply to actually know and see and understand. Paleontological research is a huge step in that process; paleoart is its creative partner.

Getting that art right—or as much as we can possibly make it ‘right’ in our relatively limited knowledge so far—is extremely important.*

“So much of palaeoart involves dinosaurs roaring and trying to kill each other,” Henry explained in an email, “which is unfortunate because not only are we pretty sure most of them didn’t roar, but also because nature isn’t like that. So much of the lives of modern animals are not represented in palaeoart: things like drinking, sleeping, patrolling, caring for young, resting, etc.

“In fact, when you look at many modern predators, not only does hunting for prey take up a vast minority of time, but most hunting attempts are unsuccessful.  I would love to see a piece showing a beaten and bruised Allosaurus looking longingly in the distance as its Camptosaurus quarry escapes.

“There are also a great deal of unusual behaviours unique to certain animal groups that are pretty likely for dinosaurs. Case in point is my Daspletosaurus, which is based on Komodo Dragons (the largest living lizards in the world, and the largest reptiles with lips, which were likely features for Tyrannosaurs like Daspletosaurus). Komodos, despite their filthy and disgusting reputation, are actually remarkably clean animals, and have been observed cleaning their muzzles of blood on bits of foliage after feeding, and I translated this to Daspletosaurus.”

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image of the Royal Ontario Museum (ROM), photo: C.E. Seo from Getty Images

Henry doesn’t just read about paleontology: he is a frequent visitor at the Royal Ontario Museum in Toronto, Canada, discussing paleontology with its experts and volunteering at their Kids’ Camp.  He is a recently published author with a scientific article in Earth Archives and other articles in the works related to Canada’s 150th year anniversary.  He writes about paleontology on his blog; he posts his artwork on his website.

It is very easy to forget that Henry Sharpe is 15 years old.

This couldn’t have been clearer when, after asking him by phone if he sells any of his art, he replied, “I don’t really get any requests now mostly because I haven’t really been around that long to advertise it.”

“But,” he continued, “down the road, I hope I can.”

His passion for art and science seem marvelously balanced by his own thoughtful sensitivity to the world around him, an awareness of the opportunities he’s had in life, a certain graciousness, and a refreshing lack of arrogance despite his considerable talent and intelligence.

When I expressed amazement at his knowledge, his humble response was, “I wouldn’t say I have the greatest breadth of knowledge, as I usually overlook obvious mistakes trying to get the rest of the painting right. For instance, in one piece I spent so much time working on the body shapes of the three protagonists (a mosasaur and two elasmosaurids) that I failed to check whether or not they would have had external ear openings (turns out they didn’t, which I found out a few months later)!”

Screenshot of artwork from his website


He credits his family for prompting his interests.  The members of his family, he wrote, “are all very much interested in science, nature, and design. They’ve also impressed the importance of knowing what you’re talking about, especially in preparation for friendly debates around the dining room table. School has also been pretty helpful, not only in its stress on locating and interpreting technical articles, but also in the expansive archive of papers the library provides (I’m pretty lucky with that).”

“They’ve always kind of encouraged critical thinking and exploring careers in science,” he continued by phone when I asked if they shared his love of art and paleontology.  “Both of my parents are kind of illustrators in their own right.  My dad is a scientific illustrator.  My mom is an interior designer, so I kind of get the technical artistic kind of thing from them.

“But, yeah, I think a lot of it is just me dragging them around to places.”

It seems that he stands alone in his passion at school, as well.

“My school is kind of half divided among the kids who want to go into the kind of more money-making fields and kids who want to go into science.  And among those, there are the few kids who want to go into biology.  And among them, there’s me, who wants to do paleontology!”

Which prompted me to ask if his friends love dinosaurs they way he does.

“[I]n terms of dinosaurs,” he replied, “no, I’m completely alone.”

He added, “I tried to start a dinosaur club and,” his emphasis here was tinged with humour, “it failed SPECTACULARLY.”

“The truth about the digital stuff that I do, most of it is just practice. There’s a great arts program at my school, but it’s kind of evenly distributed between sculpting and drawing and film studies.  So, a lot of the stuff that I’ve been doing on the computer is a lot of just me doodling away for hours on end.”

“My preferred medium is probably still pencil, for the sole reason that I can doodle inconspicuously in class when things get slow.”

This made me smile when we discussed this by phone, as I could certainly relate, thinking back to when I was in school. (How often had my friends and I done the same thing for the same reason!)

“It’s easy to pretend you’re writing something down when you have a pencil and a piece of paper, when in reality you’re just drawing a dinosaur.

“[T]his year we had a new teacher and on the first day, they caught me drawing a dinosaur on a sheet of paper.  [The teacher’s response was:] ‘Oh yeah, you’re the dinosaur kid everyone told me about!’”

But regarding his preference for pencil, Henry continued, “It’s also a great portable medium for museums and wildlife. Outside of that, I’d say it’s a tie between acrylic and digital; digital for most research projects as I can change it due to a change in research or noticing something I accidentally ignored earlier in the process, and acrylic for more landscapes, although space and time have been an issue for this.”

Screenshot of a drawing from his website


“In terms of dinosaurs, I gotta say coelurosaurs are my favourite, mostly because their feathers are somewhat easier to paint than scales. Besides them, I would love to be able to study spinosaurs; I’ve been smitten with them since seeing ‘Jurassic Park 3’,” he wrote in an email.

“Outside of dinosaurs, my biggest love is mosasaurs, which despite extensive media coverage still don’t really have the palaeontological recognition that other marine reptiles like ichthyosaurs and plesiosaurs do. There’s so much about them that no one has really explored, and I am looking forward to being able to study them in university.

“In terms of other interests, I’ve always sort of had a fascination for the arthropods of the Cambrian, Ordovician, and Carboniferous (thanks mostly to Nigel Marven in Prehistoric Park), and I would given the opportunity love to do some research regarding the pleistocene faunas of Canada.

“The biggest challenge I find is probably in the composition stage. There is a great deal of palaeoart which completely disregards aesthetics overall and opts for a more ‘dinosaur with an environment in the background’ look. There are many amazing paleoartists however that master composition and placement, ensuring that dinosaurs look not only a part of their environment, but are interacting with it as well.”

Examples he gave of such artists include James Gurney, Douglas Henderson, Danielle Dufault and Julius Csotonyi.

Partial screenshot of a beautiful painting on his website; the caption reads “Fanart based on the survival game “Saurian”, to be released in early 2017. Three Ornithomimids explore a dust hollow in a Hell Creek forest, with one speculatively (though plausibly) bathing in it, much like modern birds.”


“This is something that I’ve been trying to work on as I progress, but I still have a long way to go. The biggest reward is being done, and being able to look at the finished piece without cringing. My finishing process usually involves me getting too tired with the piece to try adding more, so if that matches up with me feeling good about it, it’s pretty great!”

Henry attributes two things for prompting his interest in paleontology: the movie “Jurassic Park” and the Royal Ontario Museum (the ROM).

“While in ‘Jurassic Park’ I could see real dinosaurs from afar, I was always kind of fascinated with how they worked from the inside, and the ROM gave me an inside look at them, while also allowing me to get up close and personal with them. The ROM was all the cooler to me when I realized that the dinosaurs of JP weren’t all that accurate anymore, and I think the concept that we knew actually very little about dinosaurs made me want to try to learn as much as I could.”

David Evans is a really great guy,” he continued. “He’s really into scientific communications.  He’s been really easy-going about me going in and trying to learn as much as I can. I’ve probably been a bit–” Here he paused as if trying to find the right word, and then said: “annoying at parts, but he’s put up with it, which is really great.”

Henry will be attending the next Society of Vertebrate Paleontology meeting in Calgary this summer. I recommend striking up a conversation with him if you go!

And be sure to keep an eye on him: there are exciting developments in his near future!


*This statement is not intended to discredit or dismiss the increasingly ENORMOUS body of paleontological knowledge that we have so far.  It is, however, meant to honestly reflect the limitations of that knowledge at this point in time.


An enormous and heartfelt THANK YOU to Henry Sharpe for his correspondence, his time speaking with me by phone, and the very generous use of his artwork on this blog!  It was a tremendous pleasure connecting with him!  I have no doubt he will make a great impact on the future of both paleoart and paleontology!


  1. Henry Sharpe’s blog:
  2. Henry Sharpe’s website/artwork:
  3. On Twitter: @bone_sharpe
  4. How pug-faced dinosaurs conquered Gondwana, Henry Sharpe, Earth Archives
  5. Get some of Henry’s artwork here at Studio 252MYA:
  6. Manitoba’s marine monsters, Henry Sharpe, Earth Archives

Screenshot of artwork from his website


Maiasaura Life History Project: The Art of Scientific Research (Part 2)

It’s one thing to be a detective. It’s another to be an artist: shifting expectations, making unlikely comparisons, causing one to consider entirely new perspectives.

Comparing elements of extant alligators and red deer to an extinct hadrosaur certainly changes how one views paleontology.  There is something unifying about it, connecting traits of living species—creatures that share the world with us today—to species that died out millions of years ago.  Instead of a scientific field one might put into a box labeled “the study of the past,” it becomes an increasingly complex vine weaving the past with the present.  And if animals as seemingly disparate as alligators, red deer and hadrosaurs share similarities, what else among us does?

Maiasaura HWB - Maiasaura replica

Maiasaura peeblesorum model; courtesy Dr. Holly Woodward Ballard

This connection was made all the more apparent in speaking with Dr. Holly Woodward Ballard about her background and her recent paper.  Her love of dinosaurs and microscopes were a perfect match for osteohistology, a field she pursued during her Masters.

Dr. Jim Farlow and Dr. Jack Horner—both members of her PhD committee and who have experience studying the bone microstructure of alligators and Maiasaura respectively—contributed to her Maiasaura peeblesorum research. They acknowledge that comparing alligator bone growth to dinosaurs has been done before; alligator bone growth has been studied extensively.

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Red deer on the Isle of Rum, however, have been studied even longer. Dr. Woodward Ballard and her colleagues found similarities to Maiasaura in their survivorship rates, as well as within their bone microstructure.

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Just as the red deer in Scotland, Maiasaura seem to have experienced a high mortality rate in the first year.  If, however, they survived that first year, they seemed more likely to live through sexual maturity, which may have been between 2-3 years of age. Eight or nine years marks another difficult year for both species. This is when their bodies appear to decline, or senesce, and they are at greater risk for mortality at this age.  Dr. Woodward Ballard and her colleagues note that one Maiasaura tibia with 10 lines of arrested growth (“LAGs”, indicating 10 years of life) appeared to still be growing.

“We have to understand the biology of modern animals and how it works before we can make any kind of hypotheses or inferences into extinct animals,” she explained. “The most important thing I learned from this experience was that we really don’t know as much as we should know about how modern animals grow and the life history details that are stored their bone tissue.”

“It’s sort of circular in that the more we learn about modern animals to apply it to the extinct ones, the more we learn about how bone biology works, how bone grows, and that has direct applications to the medical field, to veterinary biology, and to all kinds of modern fields where bone biomechanics and that sort of thing play a big role.”

Studying bones was only part of the research.  The other involved applying statistical models to the data compiled.  There are advantages to so many fossils from what the authors of the paper described as a  “monodominant” bonebed.  As mentioned in the previous post, the Maiasaura bones originate from three bonebeds in Montana, but these bonebeds are from the same stratigraphy across 2 km.  This means that the scientists can be relatively sure these animals experienced the same environmental stresses.  Differences in the bones, therefore, would indicate differences within each animal instead of being caused by external factors.

And the number of tibia studied in this paper was highly significant.

“There was one paper that came out about the mortality rates–survivorship curve distribution,” said Dr. Liz Freedman Fowler of Montana State University, co-author of Dr. Holly Woodward Ballard’s paper, “and the math in that was fairly complicated. Holly wanted to make sure that she did it right, and so that’s where I came in. It is quite complicated math making sure that you get all the different steps right.  Because the paper was critiquing and criticizing a previous paper that had done it wrong slightly, we wanted to use the methods of this kind of revision paper to make sure that we analyzed things appropriately.”

Dr. Liz Freedman Fowler new dinosaur

Dr. Liz Freedman Fowler with a painting of an entirely separate (and new!) species of hadrosaur she helped discoverProbrachylophosaurus bergei; photo by Sepp Janotta of the Montana State University News Service


“[A sample size of 50] was their suggestion,” she explained further, “because the previous histology papers that have been looking at mortality rates, they’ve been using a much smaller sample size: 10-15 individuals, [for example], which is still big for paleontology. But, you know, the smaller your sample size, the greater the chance that what you’re seeing is just random variation in your sample.  Whereas when you get a larger sample size, you can be more confident that you’re more accurately representing the population.

“Normally with dinosaurs you only have maybe two or three examples of a single species. So there’s really not much you can do mathematically because there’s just not enough data to run statistics on.”

Referenced throughout their paper was one published in Paleobiology in 2011 by David Steinsaltz and Steven Hecht Orzack.  The Steinsaltz/Orzack paper was a response to one published in Science in 2006.

“Based on [Steinsaltz and Orzack’s] modeling,” Dr. Woodward Ballard explained, “they recommended that the minimum sample size of 50 is what you would need for an extinct population in order to figure out what the shape of the survivorship curve is.  It’s not really a hard-and-fast rule.  But this is the only time that mathematicians have actually suggested a minimum number for producing statistically robust survivorship curves for dinosaurs. The fact that we were able to then meet their suggested requirements was pretty important.”

Upon first reading the paper by Dr. Woodward Ballard et al, I believed that one needed a sample of at least 50 fossils of a species in order to estimate a statistically-significant survivorship curve.  But—of all numbers—why 50? And why so many when most bones of extinct species are not as abundant as those found so far for Maiasaura?

Over the course of a conversation with Dr. Steven Orzack, I learned that what he and his co-author offered was a way to decrease potential misclassification errors in statistical calculations.

In simplest terms, they were raising the bar.

The 2006 paper by Erickson et al had used a sample size of 22 different Albertosaurus skeletons to calculate a convex survivorship curve. Convex, in other words, means that the survival rates decrease with age.

Yale - Albertosaurus side great

Cast of Albertosaurus libratus from (appropriately for this post) Red Deer River Valley, Alberta, Canada at the Yale Peabody Museum; image taken by the author of this blog


By using computer simulation to repeatedly “resample” that estimated curve, as well as a survivorship curve that was not convex (one in which some survival rates increased with age), Steinsaltz and Orzack found that about 10% of the simulated samples of size 22 taken from the non-convex sample would look convex. Such a result would mislead a scientist to misclassify the underlying survivorship curve as being convex when, in fact, it was non-convex.  When they repeated this process by more than doubling it to a sample size of 50, they discovered the misclassification error rate fell to less than 1%.

Paleontologists don’t always have access to a wealth of fossils from the same species.  This is something Dr. Orzack—trained as both a paleontologist and a neontologist—knows all too well.

HMNH - Deionychus

HMNH - Deionychus skull

Images of a partial Deinonychus skeleton, discovered in Montana in 1974 by Dr. Steven Orzack and a team of Harvard researchers, now at the Harvard Museum of Natural History; images taken by the author


“I don’t have any problem with sample sizes of 22 in the sense that if that’s the best you have, that’s fine,” he said. “What would have been better is [if Erickson et al had done] the statistics better.”

“Convexity,” he stated, “is a very specific claim.”

“[There are] weaker conclusions you can make about how survival rates change with age than [those published in the paper by Erickson et al.] If you boost your sample size to 50, you have a much lower probability of saying incorrectly that there is convexity when there isn’t,” he concluded.

“Paleontology is moving in a much more mathematical and analytical direction,” Dr. Freedman Fowler explained. “ We’re trying to be more rigorous and treat it more like a modern science.  That’s why we often use the term ‘paleobiology,’ instead of just ‘paleontology’ now. We’re trying to use the science and the tools of modern biology to look at how fossil organisms lived and kind of reconstruct their lives.”

And certainly, the math contained within the paper by Dr. Woodward Ballard, Dr. Liz Freedman Fowler and their colleagues is—to someone like myself—a bit overwhelming.

When speaking with Dr. Freedman Fowler, I asked her if her mathematical skills were rare within the field.

“I wouldn’t say ‘rare’,” she replied, “but it’s certainly not all of us. There are quite a lot of other paleontologists that use R and use math and things. But it’s a minority that goes in that direction.”

Maiasaura HWB - Maiasaura life history

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.


“Paleontology is very collaborative because it’s such a broad and interdisciplinary field. Nobody can be an expert in everything.”

When I asked her whether the sub-fields within paleontology have always been so diverse, she responded, “It is certainly a more recent development, and that’s true for many sciences.”

“[Looking back at] papers written 50 years ago, they’re almost all single authors. They’re also much more simple. These papers were just ‘I found this new species. Here’s what it looks like.’  There wasn’t much analysis.

“But now, as all these different branches of science have grown–all the different subfields within biology and geology and chemistry–we’re getting so many more tools that we can use to analyze fossils and look at them in all these different ways.  We’re also having a much larger sample size of fossils. We’re constantly out in the field collecting new specimens and that’s filling in gaps.  Between two species, [for example], we now find the intermediate species.  And we’re getting more complete growth series—the ontogenetic series—of animals. We’re out there finding juvenile dinosaurs and sub-adult dinosaurs and comparing them to the adult dinosaurs.

“Because we’re always adding this data, we always have more and more to work with. So we’re able to do types of analyses that we couldn’t 50 years ago. It was just impossible.”

And this paper is only the beginning. Dr. Woodward Ballard explained that she wants to “really make Maiasaura the dinosaur that we know the most about and really use it as a model to compare to other dinosaurs.”

In a moment of reflection, she said, “I get this question a lot:  ‘Well, great, you’re studying dinosaurs, but what’s that going to do for me?’”

She hopes that the interest in dinosaurs will pull people into science in general, describing a scenario in which the kids—wanting to see dinosaurs—visit a museum with their parents.  While there, the family may learn of other scientific discoveries, prompting even more interest in various scientific fields.

“The more we can make dinosaurs these realistic animals, [not just animals that are no longer around], I think it’s really going to get [kids] interested in science and the world around them.  Being able to continue to add more information to Maiasaura, I think, is going to be the way to really draw people in.”

“The big thing for me,” she said, “is not only collecting fossils, but [also] bringing college-aged kids to Montana to see a different part of the United States, [especially those] kids who might not [otherwise] have the opportunity to be exposed to science.”

“There’s still so much that can be done with the Maiasaura bonebed,” she continued, “with Maiasaura as an animal, so [many] opportunities for outreach and scientific investigation. I spoke with Jack Horner about this during my dissertation work and afterwards; I told him that I would really like to be able to work on Maiasaura potentially for the rest of my career. He thought it was a great idea.  I’ll do other research, too, but I plan to get out to Montana every summer.

“There’s just so much work that I decided to call it the ‘Maiasaura Life History Project’ and every paper that comes out will just be adding to what we already know about Maiasaura.”

At this time, there is no overall funding for the project. Dr. Woodward Ballard is currently writing grant proposals for future expeditions.


Holly Woodward-WCA-Branvold Quarry-Aug5-2015

Dr. Holly Woodward Ballard; photo by Dr. Karen Chin, courtesy of Dr. Woodward Ballard




  1. Maiasaura, a model organism for extinct population biology: a large sample statistical assessment of growth dynamics and survivorship; Holly N. Woodward, Elizabeth A. Freedman Fowler, James O. Farlow, John R. Horner, Paleobiology, October 2015
  2. Statistical methods for paleodemography on fossil assemblages having small numbers of specimens: an investigation of dinosaur survivorship rates; David Steinsaltz, Steven Hecht Orzack, Paleobiology, Winter 2011
  3. Largest dinosaur population growth study ever shows how Maiasaura lived and died, Montana State University, MSU News Service
  4. MSU team finds new dinosaur species, reveals evolutionary link, Montana State University, MSU News Service
  5. Tyrannosaur Life Tables: An Example of Nonavian Dinosaur Population Biology; Gregory M. Erickson, Philip J. Currie, Brian D. Inouye, Alice A. Winn


**I need to stress that the methods used in this paper and the overall research by Dr. Woodward Ballard and Dr. Liz Freedman Fowler were extremely complex. Dr. Woodard Ballard, Dr. Freedman Fowler and Dr. Orzack graciously walked me through scientific and statistical elements that I had trouble understanding. If there are any errors in this post, they are my own.

Also, while comparisons between extant and extinct species may be normal to those in the field, it was not as dramatically apparent to me until this paper. 

I would like to extend, again, an enormous THANK YOU to Dr. Holly Woodward Ballard. I would also like to extend that same thank you to Dr. Liz Freedman Fowler and Dr. Steven Orzack.  It was a great pleasure and honor speaking with each of them–not to mention fun!–and I am profoundly grateful for their generosity!  

I am very eager to learn more as the Maiasaura Life History Project continues!! 

Maiasaura Life History Project: Paleontology at an Entirely New Depth (Part 1)

I envy the future.

I really do.

Every time I read a dinosaur book—whether a kids’ book with my nieces and nephews or otherwise—I am reminded just how much we’ve learned since I was young. It is staggering, the amount of information available to dinosaur enthusiasts. Whether it is in the number of new species discovered each year, the unbelievable details paleontologists glean (from teeth alone!), or the new technology that helps scientists unravel the once unknowable.

If this is what we know now, and in the relatively brief time since paleontology was first established, what are we going to know fifty years from now? A century? A millennium?

I think about the future almost as much as I marvel at the past. Assuming our knowledge base only increases, the future of paleontology promises to reveal what can only be—at this point in time—imagined.

Which is why when I learned of the Maiasaura Life History Project, I had to know more.

Dr. Holly Woodward Ballard wants to flesh out one particular species of dinosaur such that we know it almost as intimately as living animals today.  That species is a type of hadrosaur, an extinct herbivore from the late Cretaceous. Thanks to almost 40 years of excavation in Montana, we have thousands of its fossils from which to extract information and this, according to Dr. Woodward Ballard, is to be her life’s work.

Holly Woodward-WCA-Branvold Quarry-Aug5-2015

Dr. Holly Woodward Ballard at Branvold Quarry, August 2015; Photo taken by Dr. Karen Chin, courtesy of Dr. Woodward Ballard

Maiasaura peeblesorum was inadvertently discovered in the late 1970s, both by the people who initially found the bones and by the paleontologists who eventually described them.  “Inadvertently” because Marion and John Brandvold, the people who found the bones, didn’t know what they’d found, and because Dr. Jack Horner and Bob Makela—who had done extensive research prior to their expedition—did not expect to find the object of their search in a local fossil shop they visited on a whim.

The 1988 book “Digging Dinosaurs” by Jack Horner and James Gorman describes this discovery. In it, there is a fascinating anecdote: Prior to 1978—the year Maiasaura peeblesorum was found—they say that the number of adult fossils found globally could be listed in a volume the size of a book. The number of juvenile fossils could be listed in something the size of a pamphlet.  But the number of known baby fossils could fit on an index card.

All of that changed thanks to Dr. Horner and Bob Makela. The Brandvold bones gave them specific clues about where to look and what to look for.  Their subsequent excavations revealed not only numerous baby dinosaurs, but actual nests. These significant discoveries prompted the following revolutionary ideas: that some dinosaurs may have cared for their young and that they may have been warm-blooded. The latter hypothesis continues to be debated today.

Paleontologists have been digging in the area ever since.  Their efforts have produced one of the few species of dinosaur to be so well represented in the fossil record, a fact that inspired Dr. Woodward Ballard in her research at Montana State University.

Maiasaura field site Montana

Maiasaura field site in Montana, photo courtesy of Dr. Woodward Ballard

Jack Horner, her PhD advisor, proposed the idea that she focus on population histology—revealing the growth history of a specific dinosaur species.  Given her interest in osteohistology and the wealth of Maiasaura fossils, this seemed a perfect fit.  Her dissertation was but a prelude to the work that followed.

This past October, Dr. Woodward Ballard, now of Oklahoma State University, Dr. Liz Freedman Fowler and Dr. Jack Horner of Montana State University and Dr. Jim Farlow of Indiana Purdue University published a paper in Paleobiology on the growth and survivorship rates of Maiasaura peeblesorumThe paper was unique in that, unlike most dinosaur species, they had 50 bones with which to analyze and sample.

Bone microstructure, much like trees or proboscidean tusks, records the growth of an animal in rings. In this case, Dr. Woodward Ballard was able to identify the “lines of arrested growth” (or “LAGs” for short).

“A LAG,”she explained by phone, “represents a period of missing time.”

Growth rings in Maiasaura bone

Growth rings in Maiasaura bone, courtesy of Dr. Woodward Ballard

The paper is a fascinating glimpse into the depth of detective work paleontologists must do in order to understand long extinct species. Comparing bone growth in extant reptiles and mammals to these fossil bones, using complicated statistical models, and analyzing bone structure under the microscope, the authors offer an extraordinary view into the life of Maiasaura.  It is, to date, the largest sample set of a single dinosaur species analyzed to such a degree.

Fifty Maiasaura tibiae from three Montana bonebeds provided the details. This specific leg bone was chosen for analysis because it displays histology so clearly.  The same is not true, for example, of a hadrosaur femur.

“The femur,” Dr. Woodward Ballard said, “is special in all hadrosaurs, [not just] Maiasaura. It has this big flange coming off of it, and it’s this spur bone that a fairly large tail muscle was attached to.”

“Because bone responds to stress and remodels based on the stress that’s applied to it, this flange of bone is always changing and getting larger as the [animal grows.] The remodeling that occurs within [this] bone overprints–or erases–the original signal that was there. So it’s very hard to get at that same record of growth in the femur because it’s constantly being erased in that particular area.”

One of the things they discovered through lines of arrested growth (LAGs) was that most of the tibiae in this study belonged to Maiasaura younger than a year old.

But deciphering this required understanding bone growth in living species.

“We have to use modern animals and use what we see in their bones as a basis for what we say in the fossil record,” she replied when asked about this. “We have to assume that the same processes today were working back in the Cretaceous (in this case).”

So they looked to previously published alligator studies and those of the red deer on the Isle of Rum, Scotland—one of the most extensively studied mammals anywhere in the world.

Acknowledging that these inferences should be treated with some caution, they note similarities in tibia bone growth between alligators and Maiasaura. Growth marks within the bone and lines of arrested growth (LAGs) are similar in red deer and this species of dinosaur.

“When the growth is being kept track of from year-to-year, we find that one LAG appears every year for every year of growth,” she explained.

Hence, if there are no LAGs in the bone, it indicates that the animal was less than a year. And the high mortality rate among such young animals—considerably smaller than their enormous parents and therefore not as able, perhaps, to aptly defend themselves—is not necessarily surprising.  The paper also calculates survivorship rates among Maiasaura, enabling us to know how old the dinosaur was at sexual maturity, how long it tended to live, the age at which it was at higher risk for mortality among its species.

“Once I compiled the data from Maiasaura,” she said, “got all the bone measurements, got all the LAG circumference measurements within the bones—I realized that I wanted this paper to be more than just quantitative and simple growth curve graphs. I mean, I could do that much, but I really wanted it to be statistically strong, very robust, something that followed the rules put forth by other papers, such as the Steinsaltz and Orzack paper. [Dr. Liz Freedman Fowler] was just a natural choice to have to help me figure out what to do with all this data.”


In Part 2: more detail about the Maiasaura peeblesorum survivorship curves, as well as applying complicated statistical methods to paleontological data.

An enormous and sincere thank you to Dr. Holly Woodward Ballard for her generosity: her time, her patience, her willingness to go over points I had difficulty understanding and for the beautiful pictures accompanying this post!


  1. Maiasaura, a model organism for extinct population biology: a large sample statistical assessment of growth dynamics and survivorship; Holly N. Woodward, Elizabeth A. Freedman Fowler, James O. Farlow, John R. Horner, Paleobiology, October 2015
  2. Digging Dinosaurs, John R. Horner and James Gorman, 1988, Workman Publishing Ltd
  3. Largest dinosaur population growth study ever shows how Maiasaura lived and died, Montana State University, MSU News Service

Digging Dinosaurs book cover

Jack Horner - inscription for post

Treasured copy of “Digging Dinosaurs”, the book that details the discovery of Maiasaura peeblesorum and its nests, signed by Jack Horner at the Boston Museum of Science when the author of this blog met him in 2013

Dr. Brooke Crowley – Secrets Revealed from Mammoths & Mastodons in the Cincinnati Region

It may seem unlikely to uncover details about what an animal ate thousands of years after its extinction, absent of so much of the flora and fauna that co-existed with that animal.

It might seem even more improbable to illicit that information from fossilized teeth alone.

And yet, this is exactly what Dr. Brooke Crowley and Eric Baumann of the University of Cincinnati have done.

Brooke and Eric Baumann on Kardung La

[image of Eric Baumann and Dr. Brooke Crowley on Khardung La, India; courtesy of Dr. Crowley)

They sampled molars from eight different mammoths and four mastodons, each with a known provenance in the Cincinnati region. Analyzing stable isotopes within each tooth provided information not only about each animal’s diet, but also its habitat.

“Isotopes in our tissues,” Dr. Crowley, Assistant Professor of Quaternary Paleoecology, explained in a phone interview, “are environmental integrators.”

“What we like to say is that isotope values in an animal’s tissues can tell you something about its life. That could be the diet, it could be the environment the animal inhabits, or, in the case of strontium, it could be the actual locality where it lives.”

Over the past 30 years, studying stable isotopes has become an increasingly popular method of understanding both paleontological and archaeological finds in more depth.

These chemical signatures reveal details incorporated within the body over its lifetime and remain in its bones past its death. In other words, what one eats and drinks leave traces of elements that point back to that very same diet and to the region from which one drank water. That organic material has footprints, and scientists—using mass spectrometers and other types of analysis—can read and interpret them.

Remarkably, these chemical footprints remain, even after thousands upon thousands of years. And teeth, with their sturdy crystalline structure, seem to offer reliable stable isotope data.

Dr. Crowley and recent graduate Eric Baumann described their research in a paper to be published in Boreas. Carbon isotopes revealed broad information about what these twelve proboscideans ate; strontium and oxygen isotopes uncovered the region and climate in which these animals lived.

They began their research expecting to uncover that the two species were nomadic, that their teeth were discovered in areas geographically distant from their place of origin. They also expected that mammoths and mastodons ate different types of vegetation.

While their research confirmed the different diet, it provided surprising results for habitat: with the exception of one mastodon, all of these animals actually lived and remained within the Cincinnati region.

In response to why they originally thought these animals might be nomadic, Dr. Crowley pointed to the behavior of existing species.

“Most large animals aren’t sedentary.”

“In general,” she explained, “big creatures move a fair amount; they have large stomachs and they eat a lot of food. And there may be different reasons for moving. It could be a dietary need, it could be there’s some particular nutrient in the soil that they want from time-to-time, or there may be a particular region they like for birthing or mating.”

We see this today in humpback, gray and blue whale populations on either side of the North American continent, migrating from warmer regions in the ocean to colder regions thousands of miles north.

“African elephants, in particular, are typically very destructive by nature. They are what we call ‘environmental engineers.’ Their behavior changes the environment around them.”

Perhaps the most notable affect elephants leave in their wake are the trees they knock down. Consider, too, that elephants eat 160 – 300+ pounds of vegetation a day per elephant.

“[T]hey heavily modify an area. Then they move and modify another area. And they typically have pretty large home ranges. Some populations seasonally migrate from one place to another; others are just more continuously on the move.”

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But, she cautions, “we can’t necessarily use that information to interpret the behavior of extinct species. They’re not necessarily that closely related. But it is something we have to go on.”

In their research, the authors include data from water samples taken from rivers and creeks in Ohio and Kentucky.

What, one might wonder, do modern-day water samples have to do with ancient teeth and their composition?

Strontium within water reflects the geology from which it came. This information is stored within teeth, thereby leaving yet more footprints the scientists can interpret.

Of the types of isotopes analyzed, Dr. Crowley explained that “[a] lot more work has been conducted on carbon and oxygen. So we didn’t really need to establish a local baseline for either of those two isotopes. But strontium’s a little less studied, and we didn’t know what sort of regional variability to expect.

“Without any comparative baseline, it’s hard to interpret what strontium in the animals might mean. We could say, ‘well, they’re all really similar’, but if we didn’t really know what to expect for this region, we wouldn’t know if they’re similar to the region or if all of those animals may have come from somewhere else. So we needed to establish a local baseline.”

In other words, they needed to understand the chemical signatures within local water in order to see if they matched the chemical signatures within these teeth.

“[This is] the first step,” she continued, “in what will hopefully be a long-term research direction: thinking about North American fauna and ecological change over time here on our own continent.”

When asked if this meant she would study other extinct animals or continue researching mammoths and mastodons, her response was “potentially both.”

“Currently I’m [working on a] project using strontium isotopes to look in a little more depth at particular individuals.”

Brooke and a bison scapula

[image of Dr. Brooke Crowley with a bison scapula; courtesy of Dr. Crowley]

She referenced a mastodon from Michigan as an example.

“[W]e’ve sampled little increments of his tusk to see how he moved during his lifetime.”

“One drawback of teeth,” she mentioned, “is that they just give you a relatively brief snapshot in time, whereas a tusk gives you a continuous record of an individual’s life.”

But she is equally interested in what she described as “big-scale patterns” of behavior across various species. And in this research, ‘behavior’ refers to details about their diet, and whether specific species roamed or remained in a specific region.

“If there is any living taxa that we could sample,” she added, “it would be interesting to see how they may have changed, even if they didn’t go extinct.”

“There’s interesting work that’s been done,” she said, referring to research of one of her colleagues, “[regarding the origins of] fossil deposits that indicates mastodons may have retreated to a particular part of the United States just before the Terminal Pleistocene.”

The Pleistocene is a period of time on earth that dates from about 2 million years ago through about 11-10, 000 years ago. The ‘Terminal Pleistocene’ refers to an extinction event within this period.

“Prior to the Terminal Pleistocene, they were found all over the United States. At the Terminal Pleistocene, they’re only found in a little tiny patch of the United States. Something affected their distribution. And I call it ‘retreat’ because it’s a much smaller distribution than they had before.

“By analyzing isotopes in bones and teeth, we would potentially be able to build off of these fossil distributions to paint a more interesting ecological picture of the Terminal Pleistocene.”

Painting more interesting ecological pictures is a strong focus of Dr. Crowley’s work. A scientist who has travelled extensively throughout the world, her research has taken her to the Canary Islands, the Dominican Republic, Trinidad and Madagascar. Reading her blog and her website, one recognizes a distinct fondness for the aforementioned African country.

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When asked if Madagascar was where her heart was, she responded, “In many ways, yes. Part of that is that I’ve devoted a lot of time and energy into learning a lot about it. So, now I’m invested.”

“There are certainly conservation issues in our own country,” she continued, “but there are other places–and Madagascar is one of them–where there’s a real need to try to make some changes happen now for future conservation and biodiversity management.”

“Up until recently, the recent past of Madagascar was rather understudied. It turns out that there are a lot of interesting questions that are still unanswered.”

Her website,, describes her specific interests:

I investigate ecological interactions among living and recently extinct animals using stable isotope biogeochemistry. My interests include niche partitioning, conservation biology, and paleoecology. I am particularly interested in the causes and consequences of recent extinctions, and the ecological repercussions of habitat fragmentation and degradation.

She has studied fossilized rodents, lemurs and orangutans; she has researched climate change; she has studied plants and soil.

She lists research projects in which she has been involved:

•Assessing the utility of stable oxygen isotopes in distinguishing dietary niches.

•Distinguishing isotopic niches of fossil rodents in the Dominican Republic.

•Establishing the stable isotope ecology of modern and Prehistoric Trinidad.

•Exploring ecological change following human settlement on the Canary Islands.

•Identifying responses of the animal community to climate change and human impacts in Madagascar.

•Quantifying spatial variability in bioavailable strontium and assessing changes in mobility patterns of extinct and extant North American megafauna.

Prior to the University of Cincinnati, she lectured at the University of Toronto and volunteered at the Royal Ontario Museum in the OWLS (Open the World of Learning to Students) program.

She describes herself as “a relatively new professor in Cincinnati”, one who actively works to try and include students into her research projects. In this, she feels she has been successful, as she has had a number of students involved in her postdoctoral and graduate research and currently has students working with her in the lab.

The study of proboscidean teeth that lead to the paper to be published in Boreas was, she said, “originally designed to be a student project.”

Given her vast and varied experience, one might wonder why the focus was extinct North American fauna.

Explaining that most of her students are either from Ohio or the surrounding region, she said, “It’s a little more relevant for them to think about animals that lived in their backyard than animals that lived on the other side of the planet.”

This, too, is why they used teeth from the Cincinnati Museum of Natural History, rather than the collections of other neighboring state museums.

Brooke in Madagascar2

[image of Dr. Crowley in Madagascar next to a sign that warns visitors that “Lake Ravelobe is forbidden” and that “Crocodiles attack”; courtesy of Dr. Crowley]

“Many of the reasons that I do what I do and that I am where I am is because of other people who have helped me along the way or inspired me. And really one of the biggest reasons that I wanted to go into academia in the first place was because I feel like I have been empowered in many ways to try to make a difference.

“And I feel like that’s something that I can share with others and then try to make a difference by empowering others and helping them find their way and be compassionate as well.

“So that’s sort of my goal.”

She chuckled. “I don’t know how much I have really met that goal, but I do try, and I’m still pretty new to being a professor. So, I’m finding my way. It’s a challenge, but it’s a good learning experience, and I find it to be pretty rewarding.”

Brooke on a promontory in Tenerife

[image of Dr. Crowley on a promontory in Tenerife, Canary Islands; courtesy of Dr. Crowley]


A Mammuthus primigenius-sized THANK YOU to Dr. Brooke Crowley for her generous time, help and fascinating responses to my questions!  What a great honor to connect with her!

You can read the paper in Boreas, Stable isotopes reveal ecological differences amongst now-extinct proboscideans from the Cincinnati region, USA:

I had a very difficult time grasping the concept of isotopes. This is due to my struggle with chemistry in general and not a reflection of the gracious people below who took the time to try to help me understand it.  I extend sincere thank you’s to:

  • Dr. Brooke Crowley
  • my dad
  • my sister-in-law who studies science
  • Dr. Suzanne Pilaar Birch (@suzie_birch)
  • Ariel Zych (@Arieloquent) and Science Friday (@scifri)

If you are interested in understanding more, here is further reading:

  1. Dr. Brooke Crowley, Stable Isotope Ecology:
  2. Stable Isotopes in Zooarchaeology:
  3. New insight from old bones: stable isotope analysis of fossil mammals, by Mark Clementz:
  4. Applications of Stable Isotope Analysis, K. Kris Hirst: