Caelestiventus: Beast of the Week

This week we will be checking out a newly discovered creature that is one of the oldest known pterosaurs to date.  Let's check out Caelestiventus hanseni!

Caelestiventus lived in what is now Utah, USA, during the late Triassic period, about 208 million years ago.  It was a meat-eater, and based on the bones that have been found, would have had a wingspan of almost five feet.  The genus name, Caelestiventus, translates to "heavenly wind" and the species name, hanseni, is in honor of geologist, Robin Hansen.

Life reconstruction of Caelestiventus in watercolors by me.

Caelestiventus is particularly amazing because it is the oldest known pterosaur from North America.  On top of this, it lived in an arid, desert-like environment, which is not common in currently-known pterosaurs.  Even more amazing is that the bones from Caelestiventus are beautifully preserved in three dimensions.  Most pterosaur bones tend to become flattened during the fossilization process because they are so delicate.  The fact that Caelestiventus preserved as well as it did allowed paleontologists to get a better idea of the shape of he skull.  According to what was found, Caelestiventus would have had powerful jaws, due to ridge-like structures on the top of its skull where muscles would have attached in life.  Since paleontologists were able to scan the inside of the skull, including the space its brain occupied, they found that its eyesight would have been powerful, but the senses of smell and taste less so.

3D printed cast of Caelestiventus' skull.  This pterosaur is known from an almost complete skull and a piece of the wing.

Caelestiventus was a very close relative of the more famous, and slightly later-living pterosaur, Dimorphodon.  Both of these pterosaurs had proportionally gigantic skulls that were tall and armed with differentiating kinds of teeth, which is also unusual among known pterosaurs, let alone reptiles in general.  Caelestiventus, specifically had long, pointed teeth in the front of its jaws, which would have been ideal for capturing prey, and smaller, more blade-like teeth in the back of its jaws, which appear to have been more for processing food once in the mouth.

Exactly what Caelestiventus was eating is still mostly a mystery, but we do know there were a number of small reptiles, like sphenodonts (relaitves of modern tuataras),  pseudosuchians (relatives of modern crocodilians), and even some dinosaurs, that at least as babies, could have been food items for this pterosaur.   There were almost certainly a variety of insects alive back then, as well, that could have been a staple food source for Caelestiventus.

References

Britt, B. B.; Dalla Vecchia, F. M.; Chure, D. J.; Engelmann, G. F.; Whiting, M. F.; Scheetz, R. D. (2018). "Caelestiventus hanseni gen. et sp. nov. extends the desert-dwelling pterosaur record back 65 million years". Nature Ecology & Evolution.

Britt, B. B.; Chure, D. J.; Engelmann, G. F.; Shumway, J. D. (2016). "Rise of the erg—Paleontology and paleoenvironments of the Triassic-Jurassic transition in Northeastern Utah". Geology of the Intermountain West. 3: 1–32.

Prehistoric Beast Visits The Last American Dinosaurs at the Smithsonian National Museum of Natural History

The school I teach for took a field trip to the Smithsonian National Museum of National History in Washington D.C. in the beginning of June.  Little did they suspect (actually they totally knew) I was going to have as much fun, if not more fun, than my students.  Frustratingly, the museums normal fossil hall, the David H. Koch Hall of Fossils, was under construction and will be open in June of 2019.  However, the museum knew that if they had no dinosaurs at all to show visitors there would be violent riots so they set up a great temporary exhibit, The Last American Dinosaurs.  Let's check it out!

As the title suggests, The Last American Dinosaurs showcases the creatures that lived at the very end of the Cretaceous period, called the Maastrichtian era, between 68 and 66 million years ago, from what is now Western North America.  This area is referred to as the Hell Creek formation.  These were the dinosaurs that suffered as a result of the famous meteorite hitting the earth, causing the extinction of the dinosaurs...but not really because birds are still alive.  A lot of the most famous dinosaurs lived in the United States during this time, so it was a good opportunity to show some fossils of them, alongside some not-so-well-recognized fossils from plants and other animals that also lived there.

The first thing you see when you walk in is a cast skeleton of my favorite dinosaur, Triceratops horridus!  I recognized this individual from this museum's original fossil hall, which I visited several years prior.  Casts are great to use as displays since they are lighter and therefore can be more easily mounted, less fragile and therefore are less stressful to worry about being mounted, and less valuable than the actual fossil and are therefore less of a tragedy if broken.  Finally, this lets paleontologists study the real bones in the lab behind the scenes, while the public can still enjoy what those fossils look like when they visit the museum.  Everybody wins.

The Triceratops mount is the first thing you see when you walk in this exhibit.

Next to the full Triceratops mount was a glass case that showed the inside of this magnificent dinosaur's skull.  This allowed visitors to see the size and shape of what the brain would have been relative to the rest of the skull.  It also showcased the ball-shaped section of bone on the back of the skull, that fit into a socket in the first neck vertebrae.  This ball and socket mechanism gave Triceratops and other ceratopsids a wide range of flexibility with their huge skulls.

Inside of a Triceratops' skull.

On the other side of the skeleton was another glass case showcasing casts of juvenile Triceratops and what would be considered a baby Triceratops.  Triceratops is known from a wealth of specimens of varying ages.  We now know that as a youngster, this dinosaur's horns started small, and curved upwards.  As the dinosaur continued to grow and mature, the horns began to grow forwards.  This may have been to help signal to members of its own species whether or not the animal was mature, and therefore ready to mate or engage in intraspecies combat, in which case, more forward-facing horns would be more useful.

Few creatures cuter than a baby Triceratops.  Something about those little nub horns.

You can't have an exhibit on the latest Cretaceous without a Tyrannosaurus!  This exhibit showcases a cast of "Stan", a Tyrannosaurus who's original skeleton is at the Black Hills Institute in South Dakota.  This Tyrannosaurus is famous for the teeth being exceptionally long, although this may be due to them partially falling out of their sockets after the dinosaur died.

A replica of "Stan" is the center of the exhibit.

Edmontosaurus annectens (formally known as Anatosaurus and Anatotitan) is represented by a skull.  This giant plant eater is known from some beautifully preserved specimens, that even include skin impressions.  The display here focuses on their eating habits, and the fact that they had hundreds of small teeth which were adept at pulverizing tough plant material.

Can't do an exhibit about the Maastrichtian without Edmontosaurus annectens.

This exhibit doesn't ignore the smaller, less recognized creatures of the latest Cretaceous, however.  They have a wall featuring some of the mammals, a salamander, and even plant fossils, alongside the dromaeosaurid dinosaur, Acheroraptor, on display.  Despite the fact that large dinosaurs are the most exciting to most people, it is also exciting to learn about other aspects of the environment they lived in.  Mammals, although restricted to below a certain size range during the Mesozoic, were still extremely successful, widespread and in their own right, diverse.  Plants are fascinating to think about during this time and certain species are still very mysterious as to how they would have looked and grown.  Amphibians have been around since before reptiles, let alone dinosaurs, and are still going strong in many environments today, which by itself is awe-inspiring.

Wall of unsung Maastrichtian heroes.

Lastly I'd like to show this little infograph they have hanging on the wall.  It features silhouettes of all the nonavian dinosaurs that coexisted in this environment that we know of which is pretty cool and informative considering lots of people falsely assume all dinosaurs coexisted with each other.  I couldn't help but notice that the Tyrannosaurus and Triceratops horridus appear to be taken from the original Jurassic Park concept and promotional art by Crash McCreery.  Mark Klinger's image of the oviraptorosaur, Anzu is also there.   A number of the other images look like they were taken from other artworks I've seen before and various stock images from the internet.  To the folks at the National Museum...all you needed to do was email me and I would have gladly taken the job as illustrator for you!

This was the one disappointment for me in an otherwise great exhibit.

Overall, I think this was a cool exhibit that does a great job temporarily satisfying anyone's appetite for paleontology when they visit the National Museum.  It does a good job educating the public on their old favorite dinosaurs, as well as introducing some lesser known creatures that deserve more attention.  That being said, I am still really looking forward to seeing what is in store when their permanent fossil hall is completed!

Ingentia: Prehistoric Beast of the Week

This week we'll be checking out a newly discovered dinosaur that was a giant long before we thought giants existed.  Make way for Ingentia prima!

Ingentia was a plant-eating dinosaur that lived in what is now Argentina during the Late Triassic Period, between 210 and 205 million years ago.  Sadly, only a partial skeleton is known so far from two individuals, including vertebrae, shoulder blades, and arm and hand bones.  However, this material is enough, with the help of referencing other kinds of dinosaurs that are similar and closely related, to estimate Ingentia was between twenty five and thirty three feet long from snout to tail.  This makes Ingentia the largest known animal in its environment.  The genus and species of this dinosaur translate to "First Huge One".

Ingentia prima knocking over a tree fern (and scaring the daylights out of a sphenodontid)  in watercolors by Christopher DiPiazza.

Ingentia belonged to a group of dinosaurs called the sauropodomorphs, which which are famous for having long necks and eating plants.  Brontosaurus, Apatosaurus, Diplodocus, and Brachiosaurus are probably the most recognizable members of this group.  These famous dinosaurs are from the later major branch of the sauropodomorph tree, which flourished in the late Jurassic Period, growing to gigantic proportions and sporting column-like legs and feet.  Ingentia, however, appears to have been from the earlier branch of this major group of dinosaurs that flourished in the late Triassic and early Jurassic periods which were overall smaller in size.  They are sometimes referred to as the basal sauropodomorphs, or prosauropods.  The most famous member of this group of dinosaurs would be Plateosaurus. (Which is sadly still not nearly as famous as the late Jurassic giants mentioned earlier.)  Prosauropods had five fingers and three claws on each hand, and many species walked on their hind legs.

Since Ingentia appears to be from the basal sauropodomorph group, it supports the notion that extremely large body size in dinosaurs not only started much earlier than we thought, but it also occurred twice in the sauropodomorph family tree.  Looking at cross sections of Ingentia's bones, paleontologists could tell that it was growing in spurts throughout the year, probably based on the seasons.  During the times when food was more abundant, Ingentia grew rapidly.  It's growth slowed down when resources were less available.  This is in contrast to the growth patterns we see in the later kinds of sauropodomorphs which grew constantly, but at a more steady pace.

Figure from Apaldetti's paper describing Ingentia showing the known bones.

Ingentia's vertebrae show that they would have had air sacs in them in life, like modern birds have.  Ingentia wasn't using air sacs to fly, obviously.  They would, however, be great adaptations for staying relatively light for the animal's size, which allowed it to grow much larger than a creature that had solid bones.  This is why the largest dinosaurs exceed the largest land mammals, which have solid bones, by so much.  A mammal beyond a certain size would collapse under its own density, while a dinosaur, which is much lighter for its volume, could grow much more before hitting its threshold.  Air sacs also help keep the inside of the body from overheating, and help keep a more constant supply of fresh oxygen circulating throughout the body.

Ingentia has been depicted walking on all fours in life a lot so far, but since most of its hind limbs have yet to be uncovered, we still don't know for sure if it could also walk on just two legs, as well.  There is even a chance it was an obligatory biped, only walking on its hind legs, like its later relative, Plateosaurus.
 
That is all for this time!  As always feel free to comment below!

References

Apaldetti, Cecilia; Martínez, Ricardo N.; Cerda, Ignatio A.; Pol, Diego; Alcober, Oscar (2018). "An early trend towards gigantism in Triassic sauropodomorph dinosaurs". Nature Ecology & Evolution.

Helveticosaurus: Beast of the Week

This week we will be checking out an unusual reptile with anatomy that continues to stump paleontologists.  Let's check out Helveticosaurus zollingeri!

Helveticosaurus was a marine reptile that lived during the Triassic period, about 242 million years ago, in what is now Switzerland.  From snout to tail it measured a little over six feet long.  The genus name translates to “Swiss Reptile” in reference to where this creature used to live.

Life reconstruction of Helveticosaurus in watercolors by Christopher DiPiazza.

Helveticosaurus is known from an almost complete articulated skeleton.   Because of this we have know a lot about its anatomy.  However, its combination of features is so unusual that scientists are still unsure as to what Helveticosaurus was, beyond a kind of diapsid reptile.  Diapsids have two openings in their skulls beyond their nostrils and eye sockets.  It's a vast grouping of animals, so it doesn't really narrow down what Helveticosaurus was closest related to.

Helveticosaurus skeleton on display in the Paleontology Museum of Zurich, in Switzerland.

Helveticosaurus had a long tail that was flattened laterally.  This would have been ideal for swimming.   It probably used its tail, powered by large muscles at its base, as its main mode of propulsion in the water.  However, unlike a lot of other marine reptiles, Helveticosaurus also had proportionally long, and very powerful arms.  It may have used these arms, tipped with long fingers which may have been webbed in life, to help steer while swimming.  It has also been suggested that these arms could have been another source of propulsion.

Close up of Helveticosaurus' skull.  It was broken and crushed sometime in the 242 million years since the animal died, but you can clearly make out the extremely long teeth.

The skull of Helveticosaurus is also uniquely short, almost box-shaped and its teeth were long, curved, and pointed.  The longest teeth growing from the front of the snout.  This is an especially odd combination of adaptations since most marine animals with teeth like that possess long snouts to better capture swimming prey.  Most marine animals with short snouts, like Marine Iguanas, have small teeth, that when paired with the blunt snout, are ideal for clipping underwater plants and algae.  It has also been suggested that the short snout, which allows for more concentrated power when biting down, was an adaptation for eating shelled mollusks and crustaceans, like modern walruses do.  However, animals that eat that kind of prey have blunt, wide teeth, for crushing.  Helveticosaurus' long, narrow teeth look like they'd break if they were trying to crush hard shells.  Does this mean Helveticosaurus was an evolutionary failure?  Absolutely not.  It simply means we haven't figured out how it was feeding yet.  Hopefully a new discovery or idea will help us find out in the future!  As of now, most scientists agree that Helveticosaurus was eating meat in some form, based on its teeth.  Exactly which kind and how is still a mystery.

That is all for this week!  What do you think Helveticosaurus was using its odd combination of traits for?  Leave your ideas in the comments below!

Refereces

Bernhard Peyer (1955). "Die Triasfauna der Tessiner Kalkalpen. XVIII. Helveticosaurus zollingeri, n.g. n.sp.". Schweizerische Paläontologische Abhandlungen. 72: 3–50.

Naish, D. (2008). "One of so many bizarre Triassic marine reptiles." Weblog entry. Tetrapod Zoology. 13 September 2008. Accessed 24 July 2009.

Neenan, J. M.; Klein, N.; Scheyer, T. M. (2013). "European origin of placodont marine reptiles and the evolution of crushing dentition in Placodontia". Nature Communications. 4: 1621

Dinosaurs at Nerd Nite Philadelphia

I had the privilege of being a speaker at Nerd Nite Philadelphia this week.  If you are not familiar, Nerd Nite is an organization that has people in a certain science, or other "nerdy" topic come into a bar and speak in front of an audience of other nerds about their field. 

I came in and talked about paleontology, different beasts that need more recognition, and particularly my experiences as a paleoartist and how depicting long extinct creatures certain ways can have positive, or sometimes detrimental, effects on how the public thinks about them. I also went into how it's a field that is always changing and that a hard-worked painting can become obsolete in a matter of seconds if a new, groundbreaking discovery is made.  (which is annoying, but ultimately still exciting.)

It was a lot of fun and I hope Nerd Nite decides to have me back soon.  Until then, here are a few snippets of video from the night.  

Mastodon: Beast of the Week

This week we shall be checking out a popular prehistoric mammal that has integrated itself into much of our pop culture, from Power Rangers to Heavy Metal, and even played a role in American History.  Let's look at Mammut americanus, or as it's more commonly known as, the American Mastodon!  (I will from here on out be referring this animal as Mastodon, even though Mammut is the official genus, because Mammut includes many other species that will probably be covered in the future, and will therefore be less confusing.)

A female American Mastodon in the Pleistocene marshes of what is now New Jersey.  Watercolor reconstruction by Christopher DiPiazza.

Mastodon was a member of the group of mammals that includes modern elephants, called probiscidea, that lived in what is now North America, mostly the eastern coast of the United States, between 3 million and as recent as 11 thousand years ago, during the Pleistocene.  The largest specimens could grow to be over ten feet tall at the shoulder with sixteen-foot long tusks.  Average size, however, seems to hover a bit over seven feet tall at the shoulder.  Mastodon, like modern elephants, was sexually size dimorphic, with the males typically being larger than the females.  The males also tended to have longer, and more dramatically curved tusks than the females.  The original genus name, Mastodon, translates to "Breast Tooth" because of all the cool things you could name a totally awesome prehistoric beast, Georges Cuvier, French zoologist, and founding father of paleontology, apparently just really wanted to name something after boobs back in 1817.

I don't see the resemblance.

Mastodon earned its name because its back teeth were very different from the teeth of modern elephants, and even the teeth of Woolly Mammoths, both of which had teeth that had shallow winding ridges on their surfaces for grinding up soft plants.  Mastodon's teeth were more similar to molars, and possessed tall peaks on the tops of them, which were arranged in rows. (which apparently looked like breasts to enough people in the 1800s)  Mastodon teeth were better suited at processing a wider variety of plant material, including tough twigs and pine needles.  This makes sense because these kinds of plants were abundant in Mastodon's East coast forested habitat back in the Pleistocene.  Further, Mastodon's habitat would have experiences more dramatic seasonal changes, with different plants being present during different parts of the year, so Mastodon would have needed to have food sources all year.

American Mastodon skeleton on display at the Rutgers Geology Museum in New Brunswick, New Jersey.

Other than the teeth, Mastodon had a number of other characteristics that set it apart from its relatives.  Overall its body is longer and lower to the ground, with shorter, stocky legs.  It skull was more elongated, and less tall than other elephants, and it also possessed a prominent hump over its shoulders, where big muscles that helped to support the massive skull would have been attached.  Mastodon's tusks were longer than those of an modern elephant's, and curved slightly upwards and inwards.  These tusks were probably used for a variety of jobs, just like they are in modern elephants, but because they were so long and stretched out in front of the animal, they probably were better at moving trees and brush out of the way as the animal moved through the forest.  This ensured that the sensitive trunk and eyes were less likely to get poked by a branches and thorns. These tusks were also probably used for combat between Mastodons and also helped defend it from potential predators, which would have included humans.

Mastodon also would have had a coat of bushy fur covering most of its body.  This coat probably wasn't as thick as that of a Woolly Mammoth's, but it was certainly warm enough to keep Mastodon warm during the Coastal Winters.  

Mastodon is present in American history because Thomas Jefferson, one of the United States' founding fathers, was fascinated by them.  He collected Mastodon bones, along with the fossils of as many other prehistoric animals he could get his hands on, and studied them extensively.  In fact, when Lewis and Clark were about to embark on their journey into the previously uncharted (by Europeans) Western United States, Jefferson warned them to be on the lookout for possible living Mastodons, since he believed there was still a chance they could be alive in the wilderness somewhere.  Of course, they didn't find any living Mastodons, since they had indeed gone extinct thousands of years prior, but it's cool to consider that this prehistoric elephant used to be part of cryptozoology, like Sasquatch and the various lake monsters that some people continue to hunt for today. 

No longer a cryptid due to being extinct, but still a real animal!

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

References

Agusti, Jordi & Mauricio Anton (2002). Mammoths, Sabretooths, and Hominids. New York: Columbia University Press. p. 106.

Fisher, D. C. (1996). "Extinction of Proboscideans in North America". In Shoshani, J.; Tassy, P. The Proboscidea: Evolution and Palaeoecology of Elephants and Their Relatives. Oxford, UK: Oxford University Press. pp. 296–315.

Giaimo, Cara. “Thomas Jefferson Built This Country On Mastodons.” Atlas Obscura, Atlas Obscura, 1 Sept. 2017, www.atlasobscura.com/articles/thomas-jefferson-built-this-country-on-mastodons.

Green, J. L.; DeSantis, L. R. G.; Smith, G. J. (2017). "Regional variation in the browsing diet of Pleistocene Mammut americanum (Mammalia, Proboscidea) as recorded by dental microwear textures". Palaeogeography, Palaeoclimatology, Palaeoecology. 487: 59–70. 

Larramendi, A. (2016). "Shoulder height, body mass and shape of proboscideans" (PDF). Acta Palaeontologica Polonica. 61.

Lepper, B. T.; Frolking, T. A.; Fisher, D. C.; Goldstein, G.; Sanger, J. E.; Wymer, D. A.; Ogden, J.G.; Hooge, P. E. (1991). "Intestinal Contents of a late Pleistocene Mastodont from Midcontinental North America". Quaternary Research. 36: 120–125.

Gallimimus: Beast of the Week

Today let's check out a famous member of the ornithomimd family of dinosaurs.  Make way for Gallimimus bullatus!

Gallimimus was a theropod dinosaur that lived in what is now Mongolia during the late Cretaceous, about 70 million years ago.  Adults could grow to about twenty feet long from beak to tail.  The genus name translates to "chicken mimic" because the neck bones were particularly similar to those of modern chickens and other galliform birds, like pheasants and turkeys.  The species name is in reference to a bulla, a locket-like piece of jewelry worn by young boys in ancient Rome.  The back part of Gallimimus' skull reminded some scientists of the shape of these pieces of jewelry.  When alive, Gallimimus shared its environment with other dinosaurs, including Therizinosaurus, Tarbosaurus, and fellow ornithomimid, Deinocheirus. 

Life reconstruction of Gallimimus in watercolors by Christopher DiPiazza

Gallimimus was a member of the family of theropod dinosaurs, called ornithomimidae.  Ornithomimids all had long arms, long necks, and proportionally small heads.  Most of them also had long legs and a sleek build, suggesting they could run fast.  Struthiomimus, which lived what is now North America, is another famous member of this family.  (Deinocheirus, the largest known ornithomimid, was an exception to the sleek part of the description.)  Gallimimus was probably a very fast runner when it was alive, using its long powerful legs to take huge strides and its proportionally long tail to keep balance as it ran.  Like birds today, Gallimimus had hollow chambers in its bones, which would have been filled with air sacs in life.  These sort of adaptation allows the dinosaur to intake more oxygen into its body than it would if it was only relying on its lungs.  Gallimimus also probably had a one-way breathing system, where fresh air cycled through its body in one direction, instead of in and out like the respiratory systems of mammals.  Having a more efficient way to oxygenate the body means that Gallimimus could likely run faster for longer periods of time before it got tired.  Being able to outrun predators, like Tarbosaurus, was probably Gallimimus' primary defense.

Gallimimus is known from adult and baby individuals.  What is interesting is that the baby Gallimimus, have different skull shapes than the adults, with a much shorter snouts and proportionally larger eyes.  This is consistent with many baby animals today that are cared for by their parents.  Baby crocodilians and baby birds being the two best examples to compare here. 

Baby Gallimimus skeleton on display in Cosmo Caixa Science Museum in Barcelona. Photo credit Edward Sola.

As an adult, Gallimimus had a very long, toothless snout which was tipped with a beak.  The shape of Gallimimus' beak is more broad than those of many other ornithomimids, like Struthiomimus.  The underside of the beak possessed a series of thin tube-shaped structures, which some paleontologists suggest were adaptations for filter feeding water plants and small aquatic animals, since modern ducks and geese have similar structures in their beaks for feeding this way.  Other paleontologists think the structures in Gallimimus' beak were more adapted for cutting through tough vegetation on land, instead.  In addition to plants, Gallimimus, may very well have also eaten meat in some forms, like insects and other small animals it was able to snap up.  Gallimimus also had large eye sockets, suggesting it had good vision, which it probably used to help pick out food and look out for potential predators.

Adult Gallimimus skeleton on display at the Natural History Museum in London.  Photo credit" Drow male.

The arms of Gallimimus were proportionally long, but its fingers were short compared to the fingers of other known ornithomimids.  Its arms also don't show signs of being as strong as those of other ornithomimids either.  This means that unlike many of its relatives, which probably relied on their arms and hands for manipulating food more, Gallimimus may have relied on its beak and neck for foraging more. 

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

References

Hurum, J. 2001. Lower jaw of Gallimimus bullatus. pp. 34–41. In: Mesozoic Vertebrate Life. Ed.s Tanke, D. H., Carpenter, K., Skrepnick, M. W. Indiana University Press.

Makovicky, P. J.; Kobayashi, Y.; Currie, P. J. (2004). "Ornithomimosauria". In Weishampel, D. B.; Dodson, P.; Osmolska, H. The Dinosauria (2 ed.). Berkeley: University of California Press. pp. 137–150.


Nicholls, E. L.; Russell, A. P. (1985). "Structure and function of the pectoral girdle and forelimb of Struthiomimus altus (Theropoda: Ornithomimidae)". Palaeontology. 28 (4): 64 –677.


Osmolska, H.; Roniewicz, E.; Barsbold, R. (1972). "A new dinosaur, Gallimimus bullatus n. gen., n. sp. (Ornithomimidae) from the Upper Cretaceous of Mongolia" (PDF). Palaeontologia Polonica. 27: 103–143.