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discoveries about dinosaur anatomy each year, instead of having a permanent reconstruction that will inevitably become outdated as time goes on.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.

Colors

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 leg...you 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.

Muscles

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.

Environment

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!



References


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, journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0210831.

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!

References


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, royalsocietypublishing.org/doi/full/10.1098/rspb.2017.1174

Sunday, June 23, 2019

Alanqa: Beast of the Week

Today we will be looking at an interesting pterosaur, Alanqa saharica!

Alanqa was a pterosaur that lived in what is now Morocco in Northern Africa, during the late Cretaceous Period, about 95 million years ago.  It was a relatively large pterosaur, with an estimated wingspan of up to twenty feet in the largest known individual.  The genus name translates to "phoenix"in Arabic in reference to the mythical bird.  When alive, Alanqa was most likely a meat eater.

Alanqa saharica life reconstruction in watercolors by Christopher DiPiazza.

Alanqa isn't known from too much fossil material, mostly beak and a vertebrae, but judging by these pieces, and comparing them with the proportions of other more completely known pterosaurs that were related to Alanqa, we can get a decent estimate of its overall size.  Alanqa was a member of the Azhdarchid family of pterosaurs.  Azhdarchids were primarily dominant during the Late Cretaceous and produced the largest animals to fly of all time, let alone the largest pterosaurs.  They are characterized by having proportionally huge skulls (longer than their torsos) with long tapering beaks devoid of teeth.  Many also had extremely long, but not very flexible, necks.  Azhdarchids are also thought to have been comfortable walking on land, even though evidence shows they could fly very well and for long distances, too.  A modern analog that is often made for them is today's storks and herons. (Although it is important to note that birds are NOT the same as pterosaurs.  They are purely convergent to each other.)  The extremely large Quetzalcoatlus, is the most well-known member of this family.

Part of Alanqa's beak.  Image from Ibrahim's 2010 paper.

The front of Alanqa's beak was narrow and pointed, like an extremely large pair of tweezers, great for targeting and plucking prey out of specific places, which typical for azhdarchids.  However, farther back in Alanqa's jaws were protrusions growing from the upper and lower parts of the beak, that would come together as the jaws closed.  It reminds me of the tool used to crack lobster shells, to be honest, and this very well may be what these unique adaptations were used for!  Alanqa very well may have been a specialist in eating prey with shells, like crustaceans, mollusks, and maybe even turtles?  It's also a possibility that Alanqa was an efficient scavenger and used these bony structures to crack open bones to get to the marrow inside?  I can imagine Alanqa wading around in shallow water with the narrow tip of its beak submerged, moving from side to side or probing into the mud as it uses its sense of touch to scan for any hiding prey.  When it finds something it grabs it with the tweezer-like front of its jaws then cocks its head back to maneuver the food item to the back, where it is cracked to pieces and swallowed!  This is all just speculation, of course.  But the fact of the matter is Alanqa did have a cool, unique adaptation of some kind in the back of its jaws.  We may never know for sure its purpose!

This is basically Alanqa's face...just tiny and made of metal.

That is all for this week!  As always feel free to comment below!

References

Ibrahim, Nizar; Unwin, David M; Martill, David M; Baidder, Lahssen; Zouhri, Samir (2010). "A New Pterosaur (Pterodactyloidea: Azhdarchidae) from the Upper Cretaceous of Morocco". PLoS ONE. 5 (5): e10875.


Martill, David M; Ibrahim, Nizar (2015). "An unusual modification of the jaws in cf. Alanqa, a mid-Cretaceous azhdarchid pterosaur from the Kem Kem beds of Morocco". Cretaceous Research. 53: 59.

Witton, Mark P.; Habib, Michael B.; Laudet, Vincent (15 November 2010). "On the Size and Flight Diversity of Giant Pterosaurs, the Use of Birds as Pterosaur Analogues and Comments on Pterosaur Flightlessness". PLoS ONE5 (11): e13982. 


Monday, June 3, 2019

Dakosaurus: Beast of the Week

You may know that we have reviewed a Godzilla dinosaur on here before.  This week we will be looking at yet another prehistoric beast with connections to the "King of the Monsters."  Check out Dakosaurus andiniensis!

Dakosaurus andiniensis lived in the oceans that once covered what is now Argentina during the Late Jurassic to the Early Cretaceous, between 145 and 140 million years ago.  Dakosaurus was a meat-eater in life, and measured about fifteen feet long from snout to tail.  The genus name, Dakosaurus, translates to "biter lizard/reptile" in reference to the creature's formidable teeth.  There are actually a few species within the Dakosaurus genus, but I want to focus specifically on the species, Dakosaurus andiniensis.  

Dakosaurus andiniensis by Christopher DiPiazza.

Dakosaurus was an extinct genus of crocodilian that belonged to the family called Metriorhynchidae.  Metriorhynchids were prehistoric crocodiles that were specially adapted to living in the ocean during the middle Jurassic through the early Cretaceous periods.  Their limbs were like flippers and their flattened tails even independently evolved flukes like those of sharks, dolphins, and their fellow reptiles, the ichthyosaurs and mosasaurs.

Fossilized skull of Dakosaurus andiniensis.  It looks mean!

Dakosaurus andiniensis had a uniquely short snout compared to the other species within its genus, giving it a particularly menacing look, to the scientists who studied it.  It is because of this unusually short, and boxy face, that this species of Dakosaurus was nicknamed "Godzilla" among the scientists who worked with it.

Dakosaurus' teeth were unique in that they were both laterally compressed and serrated.  This is a feature more commonly seen in certain kinds of meat-eating dinosaurs.  In fact, when the isolated teeth of Dakosaurus were first discovered, they were initially believed to have been from a Megalosaurus, not a crocodile.  The skull of Dakosaurus had openings towards the back, called fenestrae, that would have anchored powerful jaw muscles in life.  This, combined with the fact that its teeth were deeply rooted within the jaws, means that Dakosaurus would have been able to bite down with extreme force.  It is likely that an adult Dakosaurus would have been a top predator and was able to hunt most other animals it shared its habitat with, including other marine reptiles. 

Nobody is exactly sure how Dakosaurus would have reproduced.  There is specific fossil evidence that other prehistoric marine reptiles, like mosasaurs and ichthyosaurs, gave birth to live young in the water.   Dakosaurus' group, the crocodilians, however, only lay eggs in nests, however.  In fact, even broadening this group to all of archosauria, which includes crocodilians, in addition to dinosaurs and several other reptile groups, all we know of is egg-laying so far.  Going off this information alone, using closest relatives as a reference, Dakosaurus would have needed to haul out on land to lay its eggs.  However, a study looking at the anatomy of a more completely known metriorhynchid showed that the anatomy of the pelvis was more similar to that of other kinds of marine reptiles that we know gave birth to live young.  Despite that all known archosaurs lay eggs, it wouldn't be unheard of for one group of marine crocodilians to have evolved live birth, since we already can confirm it has happened multiple independent times in other groups of marine reptiles.

That is all for this week!  As always feel free to comment below.

References

Gasparini Z, Pol D, Spalletti LA. 2006. An unusual marine crocodyliform from the Jurassic-Cretaceous boundary of Patagonia. Science 311: 70-73.

Herrera, Y.; Fernandez, M.S.; Lamas, S.G.; Campos, L.; Talevi, M.; Gasparini, Z. (2017). "Morphology of the sacral region and reproductive strategies of Metriorhynchidae: a counter-inductive approach"Earth and Environmental Science Transactions of the Royal Society of Edinburgh: 1–9. 

Vignaud P, Gasparini ZB. 1996. New Dakosaurus (Crocodylomorpha, Thalattosuchia) from the Upper Jurassic of Argentina. Comptes Rendus de l'Académie des Sciences, Paris, 2 322: 245-250.

Sunday, April 28, 2019

Dryptosaurus: Beast of the Week

This week we will be looking at another extremely important, yet sadly underrepresented dinosaur.  It is also a dinosaur that is native to my home state and in some ways the unofficial mascot of this website. (It's featured on the banner above.)  Check out Dryptosaurus aquilunguis!

Dryptosaurus was a meat-eating dinosaur that lived in what is now New Jersey, on the East coast of the United States during the Late Cretaceous Period, 67 million years ago.  From snout to tail it measured about twenty five feet long.  The genus name, Dryptosaurus, translates to "Tearing Lizard/Reptile" and the species name, aquilunguis, translates to "Eagle Claw" in reference to this dinosaur's huge, curved claws, which it possessed on its hands.  Dryptosaurus was a tyrannosauroid, closely related to Eotyrannus, from England, Guanlong, from China, and to a lesser extent, Tyrannosaurus rex, from Western North America.

Dryptosaurus life reconstruction by Christopher DiPiazza.

 Dryptosaurus was one of the first prehistoric dinosaurs to be recognized by science in the United States.  Discovered only eight years after America's first discovered dinosaur, Hadrosaurus, which was also a resident of what is now New Jersey.  It was originally given the genus name, Laelaps, which is the name of a dog from Greek mythology that always succeeded in catching its prey.  Despite being a really cool name, it was soon realized that the genus name, Laelaps was already assigned to...a mite, and thus the dinosaur was changed to Dryptosaurus instead.

Dryptosaurus skeletal mounts on display at the New Jersey State Museum.

Dryptosaurus is interesting because it was a more basal kind of tyrannosauroid, like Guanlong and Eotyrannus, yet it lived much later, during the very end of the Mesozoic, at the same time as the more specialized short-armed, two fingered, tyrannosaurids, like TyrannosaurusDryptosaurus was sort of a relic of it's time, exhibiting adaptations of predators from long before.  Other than it's three-fingered hands already discussed, Dryptosaurus also possessed lighter, blade-like teeth which are in contrast to the more robust teeth of its relatives like Tyrannosaurus.  These ancestral features could have had something to do with the fact that when alive, Dryptosaurus lived isolated from the western dinosaurs of the late Cretaceous, like Tyrannosaurus and Triceratops, by a shallow sea running longitudinally down most of the center of what is now the United States, called the Western Interior Seaway.  Since it wasn't in competition with its western relatives due to geographic isolation, it may have retained its the more generalist adaptations of its ancestors. 

Dryptosaurus stands out among tyrannosauroids because its claws, especially the ones on the first digit of each hand, were the longest in proportion to the rest of the body.  It's arms were also not quite so long when compared to more basal tyrannosauroids, but still were certainly longer than those of more specialized tyrannosaurids, like Tyrannosaurus.  Despite the fact that it is only known from bones, Dryptosaurus likely had feathers.  We can assume this thanks to fossilized feathers on other tyrannosauroids, namely Yutyrannus and Dilong.

Baby Dryptosaurus (based on bones of other kinds of baby theropods) investigates a horseshoe crab.  Sea creatures may have been familiar cohabitants to Dryptosaurus.

Not much is known about Dryptosaurus' environment since the east coast of the United states has lots of human development, and therefore is more difficult to excavate for fossils now.  However, there are known fossils of duck-billed dinosaurs, armored dinosaurs, and crocodilians from the same area.  Since its environment was coastal, Dryptosaurus also may have taken advantage of aquatic animals as food like beached fish and other marine creatures, or perhaps turtles coming to shore to lay eggs. 

That is all for this week!  As always feel free to comment below or on our facebook page!

References

Brusatte, S. L. and Benson, R. B. J. and Norell, M. A. (2011) The Anatomy of Dryptosaurus aquilunguis (Dinosauria: Theropoda) and a Review of its Tyrannosauroid Affinities. American Museum Novitates, 3717 . pp. 1-53. ISSN 0003-0082

Cope, E.D. (1866). "Discovery of a gigantic dinosaur in the Cretaceous of New Jersey." Proceedings of the Academy of Natural Sciences of Philadelphia, 18: 275-279.

Monday, April 22, 2019

Toads on the Road: Sharing our Earth with Wildlife

For the past four years, whether it be New York or Philadelphia, I have been living in major cities.  Initially big cities don't seem like ideal places to see wildlife, but if you know where and how to look, amazing creatures can be found.  Since putting a birdfeeder behind my Philadelphia row home, where I thought I would only ever attract non-native House Sparrows and Pigeons, I noticed a myriad native bird species visiting my yard over just a few days.  Birds of prey, like Red-Tailed hawks hunt squirrels among tall buildings, migratory visitors, like Snowy Owls can be seen resting on telephone poles and other human-made structures before continuing their long journeys along North America, Brown Snakes emerging from hibernation from under my neighbor's wooden front steps, and if you stay diligent at night, you can see the careful raccoon or opossum making rounds through the busy urban neighborhood as they forage for meals.

Eastern Garter Snake (Thamnophis sirtalis) I found in Philadelphia.  It became docile after a few seconds after I caught it.  Never tried to bite.  (That being said don't touch wild snakes you don't know.  Sometimes they do bite.)

Once you broaden your horizons, you will find that cities have amazing public parks dedicated to preserving wild spaces to enjoy.  I'd never imagine seeing the striking Northern Shoveler, or the tiny, doll-faced, Saw-Whet Owl in a city like Philadelphia.  On my morning commute from Philadelphia to Camden, New Jersey, I have had a Bald Eagle soar over my car and on many occasions seen flocks of wild turkey strutting though the local graveyard.

Northern Shoveler (Spatula clypeata) I photographed (by putting my phone camera behind binoculars...which explains the grainy quality) at John Heins Wildlife Refuge in Philadelphia.

It's no surprise that, since they have lived here long before we have, many species of wild animal have adapted to city life.  Some even thrive in it.  However, there are others that still struggle and are in constant danger due to human development.  Amphibians, like frogs and salamanders, are extra sensitive to any sort of pollution, due to their absorbent skin, and during the spring, find themselves in mortal danger as they try to cross busy roads in an attempt to get to water so they can reproduce.  The amphibians have been making this journey every year for countless generations, long before the roads were built.  Luckily there are places like the Schuylkill Center for Environmental Education, in Philadelphia, that make a effort to ensure the journeys of local amphibians are as safe as possible. 

Every Spring thousands of American Toads (Anaxyrus americanus) and Pickerel Frogs (Lithobates palustris) emerge from their hibernation in the green spots of Philadelphia and make the relatively long, and strenuous journey to the Roxborough Reservoir where they can lay and fertilize their eggs.  Every year at this time, on nights that are warm and wet, the Scchuylkill Environmental Center gathers volunteers though their website and facebook page to come together and block off the road with the most amphibian activity and aid the tiny creatures as they embark on their journeys.  I was fortunate enough to take part in this a few times this year and it was an amazing experience.

One of the biggest human threats to amphibians is roads.  Unlike deer and other larger mammals (which still get killed by cars regularly) amphibians aren't even noticed when crossing the road by drivers, so most people can't even stop or slow down to save them.  

About ninety percent of the amphibians crossing in this place are American Toads.  American Toads come in all shades of brown, some being a beautiful reddish-orange and others being almost black, with rough bumps on their skin.  They have proportionally shorter legs and can only hop in short bursts.  For protection, they have a pair of poison glands at the base of the head that is toxic if ingested by most predators.  It is important to note that all toads are technically frogs, being part of the anura (frog) order, but not all frogs are necessarily toads.  Also there are lots of other anurids that are commonly called toads but are in separate families from American Toads and their kin, the family called bufonidae.  American Toads and other members of bufonidae typically only go into the water to breed, and prefer to spend the rest of their time on land, hiding under logs and rocks during the day.

American Toads have bumpy, dry skin, can only hop short distances, and like many members of bufonidae, have a pair of poison-filled glands at the base of their heads.

Pickerel Frogs are the other amphibian we see in this area.  They are typically green or light brown in color with dark brown square-shaped spots.  They have a pair of lighter-colored lines down their backs, and they can hop extremely far in one bound.  They have moist skin, webbed feet, and prefer to spend a lot of their time in the water.  When threatened, they can secrete an irritating substance from their skin that deters most predators from eating them.  They are very similar in appearance to Leopard Frogs (Lithobates pipiens), a close relative that overlaps with them in a lot of their range, but Pickerel Frogs have spots that are arranged in neat rows on their backs, while Leopard Frog spots are more randomly arranged.

Pickerel Frog.  Notice the large, dark spots in two rows down the back.  This is the easiest way to differentiate them from closely related Leopard Frogs, which have more randomly arranged spots.

There are certainly a wide variety of other amphibians out and about this time of year in the area, but this specific body of water seems to be the breeding spot for only these two species as far as I can tell.  Once the sun sets, and it becomes dark, on wet warm nights, the ground almost alive with toads.  At certain points I need to be careful not to accidentally step on them, they are so dense.  We gently place any toads or frogs found crossing the road in buckets, and transport them to the other side of the road, away from the danger of cars, to continue their journeys.

Because the amphibians were so numerous, we would collect and release them in buckets.  I labeled the less common Pickerel Frogs so you compare the differences between them and toads more easily.

We also record every individual animal we see on a data sheet.  We even tally the dead individuals (unlucky enough to be killed by cars earlier) in their own separate column.  This data helps the Schuylkill Center maintain an idea of how many toads and frogs are in the area, what percentage of them are surviving, and what percentage of them are being killed by cars.  One of the nights I was there the team saved over three hundred toads.  My friend and I alone saved sixty four of those toads, nine frogs, and saw ten of either species that were killed by cars.

Despite saving so many toads, this is still a scene we saw too often.  Because the toads are so dense in that area, even with a team of over twenty people blocking off the most active street and helping them cross safely, every time a car does pass through a nearby street, there is a strong chance it will kill at least one or two individuals.  Most of the carcasses we found were alive only minutes earlier.  After tallying, we moved the carcass off the road, so A) it wont get re-tallied by someone else, and B) other animals that would scavenge them can do so off the road, and avoid becoming roadkill, themselves.

If we're lucky, we get to see some toads exhibiting an interesting courtship behavior, called amplexus.  Amplexus is when the smaller male toad grasps the larger female from behind with his arms and holds on as she continues her journey.  They're not mating when they do this on land.  The male is simply getting a ride to the pond and ensuring he have a mating partner when they finally reach the water.  Once in the water, the female will lay her eggs and the male will be right there to fertilize them as they come out.  We found several pairs of toads in amplexus hopping across the road that night.

Early in the night we found a pair of toads in amplexus.  The smaller male is on top, riding his female partner to the water.  When they arrive they'll each already have partners for mating.

Many frogs are sexually dimorphic, which means the males and females look different from each other.  In the case of both American Toads and Pickerel Frogs, the Females are larger than the males.  This is partially due to the amplexus I just mentioned, since the female needs to be large and strong enough to carry her partner, and sometimes multiple partners on her back and as she travels to the water to lay eggs.  Another way to tell the difference between male and female frogs, is the males are much more vocal, being the ones to emit calls at night to attract females and compete with other males.  When we were briefly handling the toads to them cross the road, the males would often call in reaction to being touched.  This is a reflex they exhibit when they feel any sort of presence on their backs, since when breeding many males will mistakenly grab another male.  The first male will make this call to alert him of his error and to get off so they can both go back to finding a female.

As always, it doesn't need to be Earth Day for you to actively help wildlife and the wild places they live.  No matter where you are, there are nature centers, parks, and zoos always willing to accept volunteers to help preserve the precious biodiversity we share.  What do you do to help preserve wildlife where you live?  Share below!

Sunday, March 24, 2019

Hadrosaurus: Beast of the week

Today we honor a very special dinosaur.  A dinosaur that not only has roots in New Jersey, but holds significance to American paleontology as a whole.  Enter Hadrosaurus foulkiiHadrosaurus was a plant-eating dinosaur that lived in what is now New Jersey, USA, during the Late Cretaceous about 79 million years ago.  It is known from the majority of a skeleton, minus the skull (bummer), and would have been about twenty five feet long from beak to tail.  Since it was the first of its kind to be discovered, Hadrosaurus' name is used as the family name, hadrosauridae, for the entire group of duckbill-dinosaurs, like Anatotitan, Maiasaura, Parasaurolophus, and Tsintaosaurus.  Its genus name translates to "Bulky Lizard" and the species name is in honor of William Parker Foulke, who took part in its discovery.

Life reconstruction of Hadrosaurus foulkii by Christopher DiPiazza.

Hadrosaurus is a very important dinosaur not just because it was found in New Jersey, but because it was actually the first scientifically recognized dinosaur ever dug up in all of the United States!  This dinosaur's bones were found in what is now Haddonfield, New Jersey, in 1838.  The man who discovered the first of its bones actually used them as decorations on his house until they were noticed by William Parker Foulke.  Foulke was intrigued by these bones and ended up digging out more of them from where the original specimens were unearthed.  Paleontologist, Joseph Leidy, correctly identified the bones as belonging to a dinosaur because of their similarity to those of Iguanodon, which had been discovered during the 1820s in England.

Known skeleton of Hadrosaurus foulkii on display at the Academy of Natural Sciences in Philadelphia, PA.

In 1868, a skeletal mount of Hadrosaurus was erected at the Philadelphia Academy of Natural Sciences, making it the first dinosaur skeleton to be mounted in the world.  Since the skull was never found, a skull was sculpted based somewhat on modern iguanas, since dinosaurs were thought to be more closely related to lizards during that time, given the little information that was known.  It was also, however, posed standing on its hind legs which was previously unheard of for reptiles, let alone dinosaurs.  We now know that Hadrosaurus would have definitely been able to stand and walk on its hind limbs and despite the fact that a skull was never actually found, it almost certainly had a broad, flattened beak of some sort like the rest of its hadrosaur kin.

Photograph of the original Hadrosaurus skeletal mount.  Note the lizard-like skull.

Exactly how the beak and the shape Hadrosaurus' skull would have looked is somewhat of a mystery, but according to the most recent studies done on the hadrosaurid family, Hadrosaurus appears to be one of the more basal of the "true duck-billed" dinosaurs, called the hadrosaurines.  This means that it was less related to the lambeosaurine hadrosaurs, which are known for having elaborate crests, like Parasaurolophus, and was closer to the more broad-billed hadrosaurs, like Edmontosaurus.  The dinosaurs most closely related Hadrosaurus within this group have slightly downturned snouts, like that of Maiasaura, which lived a few million years after Hadrosaurus, so Hadrosaurus' skull may have looked similar.

Hadrosaurus skeletal mount on display at the Academy of Natural Sciences.  Skull is a cast of a relative, Maiasaura.

When the subject of paleontology comes up in a casual conversation (because when you hang out with dorks like me it does a lot) most envision people digging in deserts out west in states like Utah, New Mexico, or the Dakotas.  While this is true in a lot of cases, ground zero for American dinosaur fossil sites is actually in a wooded area in little old New Jersey.  Because of this, New Jersey was the first state to give itself an official state fossil, Hadrosaurus.  This means that we have two state dinosaurs, because our state bird, the Goldfinch, is a dinosaur...because birds are dinosaurs.

A dinosaur.

References

Gallagher, W.B. (2005). "Recent mosasaur discoveries from New Jersey and Delaware, USA: stratigraphy, taphonomy and implications for mosasaur extinction." Netherlands Journal of Geosciences, 84(3): 241.

Prieto-Márquez, A. (2011). "Revised diagnoses of Hadrosaurus foulkii Leidy, 1858 (the type genus and species of Hadrosauridae Cope, 1869) and Claosaurus agilis Marsh, 1872 (Dinosauria: Ornithopoda) from the Late Cretaceous of North America". Zootaxa 2765: 61–68.

Prieto-Marquez, A., Weishampel, D.B. and Horner, J.R. (2006). "The dinosaur Hadrosaurus foulkii, from the Campanian of the East Coast of North America, with a reevaluation of the genus." Acta Palaeontologica Polonica, 51(1): 77–98.

Xing, Hai, et al. “Supplementary Cranial Description of the Types of Edmontosaurus Regalis (Ornithischia: Hadrosauridae), with Comments on the Phylogenetics and Biogeography of Hadrosaurinae.” Plos One, vol. 12, no. 4, 2017, doi:10.1371/journal.pone.0175253.