Thursday, July 4, 2019

Reconstructing Hadrosaurus for the Academy of Natural Sciences

As you may have known from my facebook, instagram, or Twitter, I had the honor and privilege of working for the Academy of Natural Sciences, in Philadelphia, producing a life-sized reconstruction of the famed dinosaur, Hadrosaurus foulkii, to accompany their mounted skeleton in March this past year.  Doing a professional piece of this dinosaur, that was discovered in my home state and has been one of my favorites since childhood, has been dream come true and the whole experience was fun and educational for me from beginning to end.  Part of the process was me getting interviewed about Hadrosaurus and paleoart.  As is the case with any filmed interview, there was a LOT that I said that needed to get cut so it would fit in the small segment that is now on loop for the public to view at the exhibit.  The final cut that is currently being played at the museum is linked below.  Today I would like to share with you the entire process, and some more detailed tidbits that you may not get by visiting the exhibit, alone.

The reconstruction is part of the annually rotating "Drawn to Dinosaurs" part of the exhibit at the Academy.  Every year, a different artist is hired to produce a life-sized life reconstruction of Hadrosaurus on the wall behind the skeletal mount in chalk.  The idea behind the concept is to showcase how different paleoartists can have greatly differentiating visions of the same animal but still be equally scientifically accurate.  It also is a great opportunity to visually showcase new discoveries about dinosaur anatomy each year, instead of having a permanent reconstruction that will inevitably become outdated as time goes on.

I actually reached out and applied to the Academy two years ago with a proposal to do the job, but was initially turned down for that year.  It's easy to get frustrated in times like that, but it's so important to stay positive and keep moving forward.  This field is filled with countless skilled artists each with their own styles and backgrounds.  I feel it's more productive to celebrate and get inspired by my peers, instead of seeing them as competitors or rivals.  Their success has no affect on the quality of my work.  Only I am in control of that.

The next year I proposed my ideas to the Academy again.  This time with a sketch of what I planned to do if given the opportunity.  Having seen the Hadrosaurus reconstructions from years past by other paleoartists, like Jason Poole and Ray Troll, I wanted to make sure mine was different, but still scientifically accurate.

Concept sketch proposal I sent to the Academy of Natural Sciences for how I'd depict Haddie.

A few months later I received an email saying I had been chosen!  (It was actually a response to original proposal from the year before) I had about six months to prep myself and prepare to create the physically largest piece of paleoart of my life. (twenty five feet long and fifteen feet tall to be exact)

Fortunately, I was already comfortable drawing Hadrosaurus with regards to the proportions and colors.  I did, however, feel a need to practice with using the medium I was required to use the day of, chalk, which I had little experience with outside drawing on the sidewalk as a kid.  I popped into the museum on two separate days and played around with the chalks they had on hand on a chalkboard in one of their back rooms.  First I thought that since I would be working on a black background, I would try filling in the light spaces with the chalk and leaving the shadows and dark spaces as the black of the board, which is the opposite of what I do with most other mediums, which take place on a white background.  Ultimately, I still found it easier (for me) to simply to fill in the entire body with the base color and then work in the shadows with darker colored chalk.

One of the practice doodles I did playing around with chalk on a rolling blackboard leading up to doing the life-sized Hadrosaurus.  This version uses the black of the board for the darks and shadows, which I ultimately did not do for the final product.

The day finally arrived for me to put Hadrosaurus on the wall!  Many times when you see large pieces that take up most of or an entire wall in museums, it is created on a smaller scale by the artist, first, then blown up digitally and printed at a larger scale to be hung up.  Not the case here.  I had to draw the dinosaur directly onto the wall, all twenty five feet of it!  Further, I wasn't doing this behind the scenes.  This was taking place live over the course of two days on the actual exhibit, while the museum was open to the public, during an annual special dinosaur-themed event!  So thousands of people walked by and watched me.  Many had questions as I was working, too, which I had a lot of fun answering.  The Academy set up a camera that was filming me from beginning to end.  You can see the time lapse of the entire process below.

Among the thousands of people who came by to watch, there were a few familiar faces I was most happy to see.  Almost my entire team from my work at a nearby middle school stopped by.  Paleoartist, and longtime mentor of mine, Larry Felder made the trip over to show his support.  The Academy's resident dinosaur paleontologist and paleoartist, Jason Poole, was a steady presence and was extremely helpful with his input on the environmental pieces of the scene, having done this piece four years prior.  Paleontologist, Ted Daeschler, also was frequently checking in and kindly made a point to express how much he was enjoying my work.  Lastly, my family, including the person I was most excited to see, my wife, came by to show their support.

From left to right: Larry Felder, Me, Jason Poole.

I made a point to include lots of important details in this reconstruction of Hadrosaurus.  They aren't necessarily listed in the information under the exhibit and they may not even be visually obvious to everyone walking through.  Luckily, if you're reading this, I can list them for you.


The first three versions of this piece from the prior years all showcased a mostly green color scheme.  I really wanted to show something different, but still totally plausible.  I decided to stay mostly true to the  colors I chose for Hadrosaurus from a painting I did back in 2015.  This color scheme uses drastic countershading brown and white, with black markings on the face.  This was partially inspired by various birds that live in wetland/brackish water environments which would have been similar to the places Hadrosaurus may have been frequenting in life.  It also reminds me of many of the cool marsh birds I see when I spend time at the Jersey Shore, geographically very close to where Hadrosaurus actually roamed millions of years ago.

First painting I did of Hadrosaurus showcasing this color scheme from 2015.

The alternating bands on the tail is consistent with a lot of animals today, and when seen in reptiles, produces an illusion when the animal is moving.  As a long form with bands moves horizontally, it becomes difficult to the viewer to pinpoint where the form ends and begins.  This may have been a helpful adaptation for Hadrosaurus when dealing with potential predators.  Lastly, we actually have fossil evidence, thanks to exquisitely preserved mummified skin of a close relative of Hadrosaurus, Edmontosaurus, discovered in 1999, of a banding pattern on the tail.  The specimen has different sized scales arranged in a banding pattern, suggesting there may have been different colors there in life.

If you look closely, you can see the permanent outline of the underlying profile of the dinosaur that I ultimately made longer and thicker.

The black and white stripes on the legs could have been a communication adaptation for signaling to members of the same species, like a potential mate, or young.  We know thanks to fossils from a close relative of Hadrosaurus, called Maiasaura, that baby dinosaurs from this family were able to walk around on their own from a very small size.  A parent may have wanted its young to follow him/her for safety, like we see many species of ground birds do today, but the size difference between parent and young would have been extremely drastic, and therefore actually dangerous for the young in a way.  A parent Hadrosaurus may have had a rough time keeping track of all its brood at times.  There is also a chance mom/dad could accidentally squish one of its own young if not paying attention enough.  If the parent had bold markings on the feet and legs, it could act as a beacon at the level of its babies that could stay visible even in areas with thick vegetation that would otherwise hinder visibility.  We also know that animals alive today use black and white stripes to help deter biting insects.  A recent study on zebras show that the drastic striping pattern confuses flies that would otherwise suck blood from the larger animals.  Prehistoric dinosaurs probably had to put up with parasites and bloodsuckers, just like large animals do today, so a pattern like this may have been helpful on this front.  This is all just a hypothesis, of course, but it's fun to think about.

My Hadrosaurus has red and pink coloration on the snout and throat.  This is simply for display.  Many animals alive today, including relatives of dinosaurs, like birds and other reptiles, use bright colors like this to communicate fitness to rivals and potential mates.  I also gave my version an extensive dewlap, the loose skin under the chin and neck, similar to those you can see in many modern lizards for display, as well.

The black stripe over the eyes is an adaptation to being out in the sun.  Since dark pigments absorb light, having dark colors over the eyes helps cut glare from the sun so the animal can see more easily when it is bright out.  Many animals utilize this adaptation today that live in open environments, like the marshy floodplains Hadrosaurus may have frequented in life.  Even baseball and (American)football players put black paint on their faces during games for this exact reason!

Black markings near the eyes help minimize glare from the sun that would reflect into the eyes.  It is a common adaptation with animals that spend time in flat open spaces with little shade.  For the same reason, many athletes put black paint on their faces when they're playing on an open field.

Beak and Scales

The beak of my reconstruction is much longer and more down-turned than what you would see on the skull.  Thanks to mummified specimens of other kinds of hadrosaurid dinosaurs, like two separate specimens of Edmontosaurus, we know they would have had an extra layer of hard tissue over the beak that was made of keratin in life.  In fact, it turns out that these dinosaurs, despite being nicknamed "duck-billed dinosaurs" because of the shape of the beak of the skull alone, probably had beaks that were less flattened like that of a duck, and more downturned in life because of this layer of keratin.

We now know that hadrosaurid beaks were longer and more downturned than what the skull suggests.

My reconstruction of Hadrosaurus, as well as the four reconstructions that were done in the same place before me, have a single row of rectangular scales down the length of the back.  This isn't a coincidence.  This is based on the fact that paleontologists found a mummified specimen of a close relative, called Brachylophosaurus, which preserved impressions of these structures down the animal's back.  I took a few liberties with the shape of these, especially around the head and neck, making them more spine-like, than rectangular, since Hadrosaurus was still a different species, and therefore probably didn't look exactly the same in every way.  These structures may have been for display or they could have helped break up the dinosaur's shape making it more difficult to track by potential predators.

You can see the faint outlines of where the plate-like dorsal scales would have been on the mummified dinosaur, "Leonardo" in the top photo, compared to the similar structures I gave Hadrosaurus in the bottom photo.

We know thanks to multiple mummies of relatives of Hadrosauarus, that these dinosaurs were covered in non-overlapping scales that looked like mosaics.  Despite how much I wanted to do this on my reconstruction, I only had two days to complete it and therefore not enough time to draw in every single scale.  However, I chose to draw many scales over much of the dinosaur, giving the illusion, especially when viewed from several feet away or further, that the dinosaur was completely covered in them.

Cast of fossilized skin from the tail of a hadrosaurid mummy on display in front of the Hadrosaurus skeletal mount at the Academy of Natural Sciences with my wall art.  Original specimen is in the collections of the American Museum of Natural History, in New York.

If you look really closely at the leg, you may notice a several scales arranged in a shape that might look like an angry black cat.  This may or may not be a secret homage to my cat, Petrie.

If you look closely at Haddie's might see Petrie!

One particular specimen of an Edmontosaurus regalis shows us an impression of what the skin on the neck would have looked like, which had proportionally larger, wider scales.  I made a point to show something similar to this on my Hadrosaurus, as well.

Comparison to the fossilized neck skin imprints from Edmontosaurus regalis from Bell's 2013 paper.


There is a permanent basic outline of the dinosaur on the board for the artist to draw over, just to keep the shape and general pose intact.  However, because of some recent discoveries, I needed to greatly extend my drawing past this outline.  Thanks to many of these mummies that have been mentioned already, we know that hadrosaurids were much bulkier and more heavily muscled than previously thought.  The neck of my reconstruction is much thicker than the outline and shows plenty of folds and wrinkles as the dinosaur bends its neck upwards.

Until recently, if you looked at dinosaur reconstructions, you might notice that the legs would be separated from the tail, like you might expect for any animal, including lizards and crocodilians.  Thanks to some beautifully preserved mummies of hadrosaurids, however, we now know that there was a huge muscle connecting the back of the leg to the base of the tail on each side of the dinosaur.  this makes more sense, since these animals were much heavier, bipedal, and therefore needed more power in that region to walk around.  If you look at the muscles of modern birds that are strong runners, like ostriches, or even chickens and turkeys, you will see the same muscles.

The tail in general on my reconstruction is much thicker overall.  The ischium, the bone in the pelvis that is angled downwards and backwards under the dinosaur, would have been completely covered by flesh in life, despite sometimes being visible in older reconstructions.  We know thanks to the famous Edmontosaurus mummy, nicknamed Dakota, that these kinds of dinosaurs had very thick tails like this.


I wanted to include other organisms that Hadrosaurus may have interacted with in life in my reconstruction.  We know thanks to beautifully preserved specimens of other hadrosaurids that still had their last meal in their stomach cavities, that these dinosaurs were eating pine needles in life.  We have fossils from trees similar to modern redwood trees from the same general time as Hadrosaurus, so I included a small tree based on this, for my Hadrosaurus to munch on.

We know, thanks to a pretty extensive fossil record, that birds were alive and well during this time.  We don't have many fossils from this time in North America, and even fewer that show any characteristics that give us a good idea of what they looked like in life, but we know they were definitely around in some form.  I liked the idea of a symbiotic relationship between birds and larger dinosaurs, like certain species of birds have today with other large animals.  Oxpickers, native to Africa, are specialized in eating blood-sucking parasites off of large animals, so I created a bird based off of them with regards to beak shape, but with different colors, to accompany my Hadrosaurus.  Again, this is mostly educated guesswork of something that could have been, but isn't necessarily supported by hard evidence...yet.

There is currently no fossil evidence of birds specifically adapted to symbiotically eating parasites off of prehistoric dinosaurs, but the possibility is always there.

I included another species of bird behind my Hadrosaurus as well.  Since we know Hadrosaurus was frequenting a brackish marshy habitats most likely, I wanted to see if there were any sort of shorebirds or wading bird fossils found from that time.  Turned out there are fossils in the form of tracks from a wading bird, similar to modern herons and storks, from China during the early Cretaceous, millions of years before Hadrosaurus.  Since birds are so widespread, I decided, with some input from Jason Poole, that a wading bird similar to this would be totally plausible and safe to include in my reconstruction.  The birds I depicted have the diagnostic long legs and long toes like the tracks show.  I took more liberties with the neck and beak, however, to be a bit less specialized.

We have fossil evidence that wading birds were flourishing by the time of Hadrosaurus.

Lastly, I included possibly my favorite invertebrates, horsehoe crabs.  Horsehoe crabs we know have been around since hundreds of millions of years before the first dinosaurs.  Since there are horshoe crabs frequenting the shores of New Jersey today, it is possible their ancient ancestors were doing the same back then.  I drew inspiration from the countless horseshoe crabs I've found washed up at the Jersey Shore, many of which had entire communities of barnacles and bivalves living on their shells.

Now you know a bit of the thought behind my Hadrosaurus at the Academy of Natural Sciences.  As I stated earlier, this is a yearly exhibit, so in March of 2020, it will be replaced by the work of another artist, so if you ever find yourself in or near Philadelphia in the next year, make a trip over!


Bell, P. R.; Fanti, F.; Currie, P. J.; Arbour, V.M. (2013). "A Mummified Duck-Billed Dinosaur with a Soft-Tissue Cock's Comb". Current Biology. 24 (1): 70–75.

Caro, Tim, et al. “Benefits of Zebra Stripes: Behaviour of Tabanid Flies around Zebras and Horses.” PLOS ONE, Public Library of Science,

Morris, William J. (1970). “Hadrosaurian dinosaur bills — morphology and function“. Contributions in Science (Los Angeles County Museum of Natural History) 193: 1–14.

Murphy, Nate L.; Trexler, David; Thompson, Mark (2006). ""Leonardo," a mummified Brachylophosaurus from the Judith River Formation". In Carpenter, Kenneth (ed.). Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs. Bloomington and Indianapolis: Indiana University Press. pp. 117–133.

"Mummified Dinosaur Unveiled". National Geographic News. 2007-12-03. Retrieved 2007-12-03.

Osborn, Henry Fairfield (1912). "Integument of the iguanodont dinosaur Trachodon". Memoirs of the American Museum of Natural History. 1: 33–35, 46–54.

Xing, Lida, et al. “Reanalysis of Wupus Agilis (Early Cretaceous) of Chongqing, China as a Large Avian Trace: Differentiating between Large Bird and Small Non-Avian Theropod Tracks.” Plos One, vol. 10, no. 5, 2015, doi:10.1371/journal.pone.0124039.

Tuesday, July 2, 2019

Vespersaurus: Beast of the Week

Today we will be looking at a truly unique, recently discovered species of dinosaur.  Let's check out Vespersaurus paranaensis!

Vespersaurus was a theropod dinosaur that lived in what is now Brazil, during the Cretaceous Period, about 90 million years ago.  From snout to tail, Vespersaurus would have measured a little over six feet long.  The genus name translates from Latin to "Western Reptile" in honor to Cruzeiro do Oeste (which means Western Cross), the town where the bones were uncovered. 

Vespersaurus paranaensis life reconstruction in watercolors by Christopher DiPiazza.

Vespersaurus was a member of the noasaurid family.  Noasaurids were theropods that primarily flourished in the Southern Hemisphere during the Cretaceous period and are within the larger, more diverse ceratosaur clad, which includes more famous dinosaurs, like Ceratosaurus and Carnotaurus.  Unlike these larger relatives, however, noasaurids tended to be much smaller, and more lightly built, with longer necks and proportionally smaller heads.  Another, recently more popular noasaurid, and therefore much closer relative to Vespersaurus, was Masiakasaurus, which was found in Madagascar and had a distinctive, down-turned lower jaw with teeth that jutted out forward.  Because so little of Vespersaurus' skull was found, it is unknown if it had a similar down-turned jaw or not.  If it did, Masiakasaurus may not be that unique, and the trait might just be a more widespread ancestral adaptation to the noasaurid family.

Articulated foot of Vespersaurus.

When it came to Vespersaurus' legs and feet, however, it truly was unique.  In fact, Vespersaurus' feet are unlike anything ever seen before in reptiles, let alone dinosaurs!  Vespersaurus had what are called funtionally monodactyl feet.  Monodactyl means one toe per foot.  Funtionally monodactyl means that the animal had more than one toe on each foot, but was only using one toe to actually walk.  In the case of Vespersaurus, it had the first digit of each foot was higher on the leg and didn't touch the ground (typical for nonavian theropods), but the second, and fourth digits, which normally would touch the ground in other dinosaurs, were unusually thin and would have been carried off the ground when walking.  All the weight was put on its third digit.  Amazingly enough, prior to the discovery of Vespersaurus' bones, paleontologists found very strange tracks from Argentina, which show what appears to be a theropod dinosaur walking on its central toe.  These tracks are a bit older than Vespersaurus, and they possibly could have only simply appeared to have been only walking on one toe, and the side toes just weren't making as deep of an impression, but they are still important to note.  We we know dromaeosaurids, the group that includes Velociraptor, carried one specialized toe off the ground and walked on two, and there are modern birds (also dinosaurs) that have only two toes on each foot, like ostriches, but only one walking tow is completely unheard of.

One-toed theropod track, possibly an earlier relative of Vespersaurus.

Vespersaurus certainly had unique feet for a dinosaur, and even a reptile, bur this sort of foot plan HAS evolved before...just in a different group of animals.  In fact, it happened in a very popular group of animals that everyone knows, horses!  Everyone knows horses only have one hoof per foot, which is just one big toe.  Fortunately, we have a very detailed fossil record of horse ancestors, which shows that millions of years ago, prehistoric horses were walking on three toes, and over time the side toes grew shorter and eventually became useless, leaving everything to the middle toe, ultimately resulting hooves we recognize today.  It makes me wonder if Vespersaurus had not gone extinct, if its descendants would have had only one toe per foot, too.  Since Vespersaurus lived 90 million years ago, tens of millions of years before the mass extinction event that wiped out the non-avian dinosaurs, maybe there was a later, more derived noasaurid that has this foot plan that paleontologists just haven't found?

Illustration of prehistoric horse foot bones.  Oldest to youngest from left to right.  Note how side toes become smaller and eventually disappear, leaving a singular, walking toe.(image from Outlines of Zoology, by J. Arthur Thomson.)

So why the unusual one toe on each foot?  Well, if we go back to horses, which have a convergently similar adaptation, we may get some clues.  We know horses evolved these feet to run faster.  When the weight of an animal's foot is on a more concentrated spot, it provides more resistance against stress when weight is applied on it, and therefore results in a stronger runner.  Looking at the rest of Vespersaurus' known bones, it makes sense that it would have been a very fast runner.  It also lived in an arid desert environment, with lots of open space, where being able to run long distances more easily would certainly be an advantage.  What environmental pressures would have caused Vespersaurus to have evolved such an extreme running adaptation?  Unfortunately the diversity of fossils from the site Vespersaurus was found in is still limited, Vespersaurus being the only known dinosaur so far, so we have no idea what kind of predators it would have had, if any.  On the other end, Vespersaurus had small teeth that were short, but serrated, so it was possibly at least eating some meat.  Perhaps Vespersaurus was really good at chasing down small prey? It's still a mystery!

Tooth of Vespersaurus.

That is all for this week! Comment below with your thoughts!


Glut, Donald F. (2003). "Appendix: Dinosaur Tracks and Eggs". Dinosaurs: The Encyclopedia. 3rd Supplement. Jefferson, North Carolina: McFarland & Company, Inc. pp. 613–652.

J. Arthur Thomson, M.A., LL.D. Outlines of Zoology (New York, NY: D. Appleton & Company, 1916)

Langer, Max Cardoso; de Oliveira Martins, Neurides; Manzig, Paulo César; de Souza Ferreira,, Gabriel; de Almeida Marsola, Júlio César; Fortes, Edison; Lima, Rosana; Sant’ana, Lucas Cesar Frediani; da Silva Vidal, Luciano; da Silva Lorençato, Rosangela Honório; Ezcurra, Martín Daniel Ezcurra (2019). "A new desert-dwelling dinosaur (Theropoda, Noasaurinae) from the Cretaceous of south Brazil". Scientific Reports. 9.

“Mechanics of Evolutionary Digit Reduction in Fossil Horses (Equidae).” Proceedings of the Royal Society B: Biological Sciences,