Sunday, February 4, 2024

Ornithomimus: Beast of the Week

 This week we will be looking at a fast-running dinosaur that looked like modern birds. (but wasn't directly related to them) Make way for Ornithomimus!

Ornithomimus was a theropod dinosaur that lived in what is now mostly western North America, although some fragmentary fossils that appear to be from it have also been found on the east coast of the United States, including New Jersey.  It lived during the late Cretaceous period, between 76.5 and 66 million years ago, and therefore was one of the dinosaurs wiped out by the meteorite that ended the Mesozoic.  From beak to tail it would have measured about 12 feet (3.6 meters) long and was either an herbivore, or possibly an omnivore when alive.  Its genus name translates to "Bird Mimic" because of its birdlike (specifically ostrich) appearance.  

Ornithomimus edmontonicus life reconstruction in watercolors by Christopher DiPiazza.

Ornithomimus was a member of the ornithomimosaur family of theropods, characterized by their long, slender necks, long legs, long arms, and beaked faces.  Like Ornithomimus, many were toothless, but a few earlier members had small teeth.  Struthiomimus, Gallimimus, Harpymimus, and even the gigantic Deinocheirus, are all also members of this group.  Like many of its relatives, Ornithomimus had proportionally long arms with three fingers on each hand and long powerful legs, suggesting it was a fast runner.  A large number of Ornithomimus foot bones on the fossil record were found by paleontologists to be devoid of stress fractures, further supporting the idea they were adapted to running in life. Ornithomimus also had a slender beak with proportionally large eye sockets, suggesting it had strong eyesight in life.  

Ornithomimus edmontonicus skeleton on display at the Royal Tyrell Museum in Alberta, Canada.

Ornithomimus is currently known from two species.  The earliest of the two, called Ornithomimus edmontonicus, lived between 75.5 to 72 million years ago, in what is now Alberta, Canada.  It would have coexisted with other dinosaurs, like Albertosaurus, Anodontosaurus, Pachyrhinosaurus, Sphaerotholus, Hypacrosaurus, and its close relative, Struthiomimus.  The later species, Ornithomimus velox, was the slightly smaller species based on known material, and lived more in what is now the United States, from the very end of the late Cretaceous.  This species would have crossed paths with Tyrannosaurus, Triceratops, Pachycephalosaurus, Anzu, and Ankylosaurus to name a few, and like them, would have gone extinct when the asteroid that ended the Mesozoic hit the earth, 66 million years ago.  In the past Ornithomimus actually included a whopping seventeen more species that have since mostly been lumped into one of the two previously mentioned, or found to be different genera.

Fossilized remains of Ornithomimus feathers circled in yellow.  Specimen at the Royal Tyrell Museum.

For decades most experts suspected Ornithomimosaurs, like Ornithomimus, sported feathers in life based on its resemblance to modern birds and the presence of fossilized feathers in other kinds of dinosaurs.  More recently, however, this hypothesis was confirmed thanks to not one, but several separate specimens of Ornithomimus edmontonicus that sport fossilized remains of feathers.  Thanks to these exquisite fossils, we now know that young Ornithomimus had shaggy down-like feathers on their bodies, much like many modern birds.  We also know that adult Ornithomimus sported long feathers on its lower arms, like the wings of modern ostriches. It is worth noting that the Ornithomimosaurs were NOT direct ancestors of modern ostriches or any other birds (modern types of birds already existed during the time ornithomimosaurs were alive), but a beautiful example of convergent evolution, when two different kinds of animals independently evolve similar features and end up looking more closely related than they really are.

References

Makovicky, P.J., Kobayashi, Y., and Currie, P.J. (2004). "Ornithomimosauria." In Weishampel, D.B., Dodson, P., & Osmólska, H. (eds.), The Dinosauria (second edition). University of California Press, Berkeley: 137-150.

Rothschild, B., Tanke, D. H., and Ford, T. L., 2001, Theropod stress fractures and tendon avulsions as a clue to activity: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 331-336.

Zelenitsky, D. K.; Therrien, F.; Erickson, G. M.; Debuhr, C. L.; Kobayashi, Y.; Eberth, D. A.; Hadfield, F. (2012). "Feathered Non-Avian Dinosaurs from North America Provide Insight into Wing Origins". Science338 (6106): 510–514.

Sunday, January 14, 2024

Stegosaurus: Beast of the Week

This week we will be looking at one of the most instantly recognizable dinosaurs.  Let's check out Stegosaurus

Stegosaurus was a plant-eating dinosaur that lived in what is now the Western United States, including Wyoming and Colorado, during the Late Jurassic Period, between 155 to 150 million years ago.  Some Stegosaurus remains have also been found in Portugal.  The genus name, Stegosaurus, actually translates to "roofed reptile" because its iconic plates were at first believed by scientists to have laid flat on the animal's back like shingles on a roof.  As adults, most Stegosaurus hovered in size at around twenty to twenty five feet, but some individuals could have grown to about thirty feet long from beak to tail.  When alive, it would have coexisted with other famous dinosaurs, including Apatosaurus, Brontosaurus, Camarasaurus, Ceratosaurus, Torvosaurus, and Allosaurus.

Life reconstruction in watercolors of Stegosaurus stenops by Christopher DiPiazza.  Since its center of gravity was over the hips, it may have been easier for Stegosaurus to rear up on its hind legs than most quadrupedal dinosaurs, especially if it used its strong tail as a third support.

Stegosaurus is most well-known for its plates, which varied slightly between species, but more or less were diamond-shaped, depending on the species.  The speceis, Stegosaurus ungulatus, had more narrow and pointier plates.  Stegosaurus stenops had plates that were wider and more rounded.  On average, Stegosaurus possessed seventeen to nineteen of these impressive plates running down its back.  The evolutionary function of these bony structures remains a mystery but paleontologists have come up with a few ideas.  When first discovered, it was believed that these plates served as armor, but it was soon realized that in life, they were arranged sitting erect on the animal's back which wouldn't do much good for physical protection from predators.  Furthermore, the plates of a Stegosaurus are extremely thin and actually quite delicate!  A predator, like Allosaurus or Torvosaurus, would surely have had no problem biting right through them.


Stegosaurus stenops skeleton on display at the American Museum of Natural History in New York.

A second, possably more likely idea for these plates, was to help control Stegosaurus' body temperature.  Upon close inspection, they were found to have had many blood vessels in them in life.  If a Stegosaurus wanted to warm up in the morning, the blood in these plates could have been heated by the sun and then circulated to the rest of the body.  If the Stegosaurus wanted to cool off in the afternoon, the heated blood would cool off slightly when closer to the outside air while in the plates, and like before, be circulated to the rest of the body, cooling the animal down.  Many other animals use this method of temperature control, by using large ears like elephants and rabbits, or reptiles with sails or extendable ribs.  It is plausible that Stegosaurus' plates were also display adaptations, having possibly been brightly colored to impress potential mates or intimidate rivals.  

Stegosaurus stenops skeletal mount on display at the London Museum of Natural History.

The position of Stegosaurus's plates has also been the subject of some debate over the years.  Like I stated earlier, originally the plates were believed to have laid flat on the dinosaur's back, like shingles on a roof, for protection.  It was later realized that these plates belonged erect  growing off of the back.  The first version of this idea showed two rows of paired plates but the more recent idea is that the plates were still in two rows, but alternating, not parallel.  Other members of the stegosaurid family, like Kentrosaurus, for instance, did actually have parallel paired plates, however.

Stegosaurus had actual protective armor too!  Right under the chin, extending down the throat of a well-preserved Stegosaurus specimen, many small pieces of bony armor were discovered.  These small chunks of armor would have been embedded in the dinosaur's neck skin and acted like chain mail, protecting the throat from biting predators.  This neck armor is called gular armor. ("Gular" means throat.)  

The actual skull of Stegosaurus was extremely small in comparison to the rest of the body.  The skull of Stegosaurus was narrow, and was tipped with a short beak, which the dinosaur used to clip vegetation.  This food then would have been processed with Stegosaurus' small teeth further down into the mouth, which were also adapted for clipping and shearing vegetation.

Skeletal mount of Stegosaurus showcasing the gular armor.

At the opposite end of the body, at the very tip of the tail, Stegosaurus possessed four long spikes.  Stegosaurus would have been able to swing its tail around with deadly accuracy to keep any potential predators at bay if it was ever attacked.  Since Stegosaurus' hind limbs were so much longer than its front limbs, its center of gravity was near its hips rather than closer to the rib cage like it is with many other quadrupedal dinosaurs.  This would have enabled Stegosaurus to use its front limbs to help it rotate its body around more rapidly than one would expect from an animal of that size, greatly increasing its tail-swinging range.  This makes sense since potential predators would likely be aiming for its head and trying to specifically avoid its tail.

Tail of Stegosaurus.

 The pelvis of Stegosaurus also possessed an odd hollow section which is still somewhat of a mystery to scientists.  At first, this area was believed to be the site of a swelling of nerves, which could have acted as a "second brain" to control the animal's back half, since the actual brain was so small.  Scientists now know this is untrue and that this area appears to be for storing glycogen, a kind of molecule which animals can use for energy.  Glycogen bodies, similar to the one found in Stegosaurus', pelvis can also be found in the hips of modern birds and other reptiles.

That is all for this week!  As always feel free to comment below or on our facebook page!  Have a particular beast you would like to see painted and reviewed?  Let me know and I will add it to the list!

References

Buchholz (née Giffin) EB (1990). "Gross Spinal Anatomy and Limb Use in Living and Fossil Reptiles". Paleobiology 16: 448–58.

Buffrénil (1986). "Growth and Function of Stegosaurus Plates". Paleobiology 12: 459–73.

Carpenter K, Sanders F, McWhinney L, Wood L (2005). "Evidence for predator-prey relationships: Examples for Allosaurus and Stegosaurus.". In Carpenter, Kenneth(ed). The Carnivorous Dinosaurs. Indiana University Press. pp. 325–50. ISBN 0-253-34539-1.

Czerkas SA (1987). "A Reevaluation of the Plate Arrangement on Stegosaurus stenops". In Czerkas SJ, Olson EC. Dinosaurs Past & Present, Vol 2. University of Washington Press, Seattle. pp. 82–99. ISBN.

Lull, R. S. "The Armor of Stegosaurus." American Journal of Science S4-29.171 (1910): 201-10. Web. 

Saitta ET (2015) Evidence for Sexual Dimorphism in the Plated Dinosaur Stegosaurus mjosi (Ornithischia, Stegosauria) from the Morrison Formation (Upper Jurassic) of Western USA. PLoS ONE 10(4): e0123503. doi:10.1371/journal.pone.0123503



Sunday, December 31, 2023

Furcatoceratops: Beast of the Week

 This week we'll be checking out a newly described ceratopsian, Furcatoceratops elucidans!

Furcatoceratops was a ceratopsian dinosaur that lived in what is now Montana, USA, during the late Cretaceous period, between 76 and 75 million years ago.  From beak to tail it measured about thirteen feet (4 meters) long.  The genus name translates to "Forked-horned Face" and the species name, elucidans, means "enlightening".  Like all known ceratopsians, Furcatoceratops likely ate plants when it was alive.

Watercolor life reconstruction of Furcatoceratops by Christopher DiPiazza.  The crossed horns is speculation based on the fact that there would have been keratin growing over the fossilized horn cores (which are very close together) in life.  

Amazingly, Furcatoceratops is known from an almost complete skeleton, which is rare for dinosaur fossils.  As is the case with most ceratopsians, its most notable feature is its horns.  Furcatoceratops had two horns growing from above its eyes that are quite close together, basically parallel to each other. This is unusual compared to the brow horns of other ceratopsian dinosaurs, which tend to grow angled away from each other.  Furcatoceratops also had a series of small, triangular horns growing from the perimeter of its frill.  Many ceratopsians also have a horn on the snout over the nostrils but since that portion of Furcatoceratops' skull was one of the few parts not found, it is unclear if it also had a horn there in life.  

As which all ceratopsians, the exact evolutionary purpose of Furcatoceratops' horns is unknown, but display within its species or defense against potential predators are possibilities.  Lower on the skull, Furcatoceratops had a sharp beak backed up by many small teeth that would work together like shears for processing mouthfulls of plants when alive. 

Furcatoceratops skeleton on display at the National Museum of Nature and Science in Tsukuba, Japan. (photo credit: "eight heads serpent")

Within the ceratopsian group (dinosaurs known for their horns and bony frills) Furcatoceratops is part of the centrosaurine branch of the family tree.  Centrosaurines are known for having robust, tall snouts, and proportionally shorter frills.  Within this group, Furcatoceratops appears to be particularly closely related to Nasutoceratops, which was alive during almost the same time as Furcatoceratops in what is now Utah, USA.  

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

References

Ishikawa, H.; Tsuihiji, T.; Manabe, M. (2023). "Furcatoceratops elucidans, a new centrosaurine (Ornithischia: Ceratopsidae) from the upper Campanian Judith River Formation, Montana, USA". Cretaceous Research. 105660.

Sunday, December 10, 2023

Visiting the Pokemon Fossil Museum

 I was fortunate enough to take a trip to Japan this past summer with friends and family. We are all big Pokemon fans, my wife and I having played the games since the late 90s, and my daughter enjoying the anime, so we naturally had a lot of fun visiting several of the official Pokemon centers and other attractions throughout the country during our three weeks in the country.  One of the must-sees was to visit the Pokemon Fossil Museum, a traveling exhibit that showcases fabricated skeletons and models of prehistoric Pokemon alongside casts of the real dinosaur and other prehistoric animal fossils they're based on.  

Model of what the skeleton of the Pokemon, Tyrantrum, might look like on display in the main hall of the museum, before entering the exhibit. My daughter and I for scale.

Upon entering the exhibit visitors are greeted by a model of the pterosaur Pokemon, Aerodactyl, being ridden by a Pikachu (because of course there's Pikachu) dressed like a paleontologist. Pikachu was never one of my favorite Pokemon but I must admit this version of the electric mouse was very cute.  "Paleontologist Pikachu" would be portrayed several more times throughout the exhibit acting as a sort of guide, and was shown interacting with various prehistoric Pokemon.  Regarding Aerodactyl, despite being one of the original fossil Pokemon from the first generation of the franchise, there is no actual skeleton of it in the exhibit.  It is mentioned and depicted again alongside a cast of a Pteranodon, Dimorphodon, and Pterodactylus, demonstrating pterosaur anatomy, however. 

Aerodactyl and Paleontologist Pikachu are the first pokemon models you meet upon entering.  Sadly there was no Aerodactyl skeleton on display anywhere. 

Casts of the skeletons of Pteranodon and Dimorphodon hanging from the ceiling.

Two more of my favorite Pokemon, Cranidos and Rampardos, based on pachycephalosaurs, were also not featured as models or skeletons, but they are mentioned alongside casts of two different Pachycephalosaurus skulls.  

Pachycephalosaur section of the exhibit.  It was cool to see two different Pachycehpalosaurus specimens on display next to each other.  Sadly there were not models or skeletons of Cranidos or Rampardos on display anywhere.

The exhibit showcases quite a few ceratopsian pieces, including a (real?) Protoceratops skull and a baby Triceratops skull cast that appears to have been filled in quite a bit.  It doesn't match the other baby Triceratops skulls I've seen in photos of and in person at other museums.  They also have a model of what I'm pretty sure is the Triceratops prorsus skull, from the Yale Peabody Museum.  These pieces are showcased alongside a full skeleton model of the ceratopsian Pokemon, Bastiodon.

Protoceratops and baby Triceratops skull cast.  You can tell what parts of the Triceratops are reconstructed by the smooth texture.

The ceratopsian part of the exhibit, flanked by skeleton of the pokemon, Bastion in the background, and model of Triceratops prorsus skull in the foreground.

The main hall of the exhibit showcases full skeletal mounts of the sauropod Pokemon, Aurorus, and the real dinosaur it's based on, Amargasaurus, opposite each other where visitors can compare them side by side.  Amargasaurus is known for the long, bony extensions growing from the top of its neck vertebrae, which may have formed a sail or hump in life. Aurorus design took this feature and turned it into an aurora borealis-like structure that ripples like a flag.  The signage explicitly mentions that the structure on the Pokemon has no bones supporting it, but the skeletal model has pieces for it.  I'm assuming to keep the skeleton recognizable especially to younger visitors.  Makes me think of how some skeletal mounts of real dinosaurs include physical outlines of soft parts, like wings or even attach real arm feathers to the bones to showcase structures that would have been present in life. 

The Pokemon, Aurorus, and dinosaur, Amargasaurus were the two largest pieces in the exhibit.

Beautiful Amargasaurus.  This was my first time seeing a skeletal mount of this dinosaur in person.

Aurorus is one of my all time favorite Pokemon so it was a delight to see this model skeleton.

There was of course a theropod section, with a cast of the original Megalosaurus jaw discovered in the 1800s, alongside a cast of what is labelled as a baby Tyrannosaurus skull.  I was unfamiliar with this specimen so I reached out to paleontologist and tyrannosaur expert, Dr. Thomas Holtz, who was kind enough to share that it appears to be of a two-year old Tyrannosaurus specimen housed in Los Angeles.  The actual specimen is only known from the very front of the snout and lower jaw, and a part of the top of the cranium, so most of the skull on display here is reconstructed.  These are showcased alongside a model skeleton of the tyrannosaur Pokemon, Tyrunt.  I appreciate how the design of the Pokemon shows the teeth as part of the actual jaw, instead of in sockets, like the Pokemon's design suggests. 

Megalosaurus jaw cast and the mostly reconstructed baby Tyrannosaurus skull cast.

Skeleton model of the tyrannosaur pokemon, Tyrunt.

The link between theropod dinosaurs and modern birds is also addressed with a skeleton model of the feathered dinosaur Pokemon, Archen, alongside a standing skeletal mount and cast of the famous Archaeopteryx specimen, housed in Berlin.

Check out that beautiful Archaeopteryx art by Hitoshi Ariga.

Archen, which is mostly based on Archaeopteryx, skeleton on display.

I was impressed by how much attention was given invertebrate fossils in this exhibit, particularly ammonites.  In fact, the most extensive collection on display in the exhibit was of ammonites, which were of course shown alongside their Pokemon counterparts, Ammonite and Omastar.  

This exhibit showcased an extensive collection of real ammonite fossils packed with information.

Other invertebrate Pokemon were represented, including the flying bug-type Pokemon, Yanmega, alongside casts of the real prehistoric flying insect, Meganeura.  Fossils of crinoids alongside models of the Pokemon Lileep were present, and of course horseshoe crabs alongside the Pokemon, Kabuto and a skeleton of its evolved form, Kabutops.  

Comparing the Pokemon, Kabuto, to horsehoe crabs.  I love how the eyes on the model appeared to be glowing.

Kabutops skeleton model.  I'm assuming it's meant to represent a fossilized exoskeleton?  I remember seeing a little pixelated image of this in the museum part of the old Pokemon gameboy game.

One very entertaining aspect of this exhibit for Pokemon fans was the models of the fossil items obtained in the video game that can be turned into Pokemon on display.  My favorite example of this is the "old amber" fossil item, used to resurrect Aerodactyl in the game, displayed alongside real pieces of fossil amber.  

"Old Amber" from the Pokemon games alongside some real fossilized amber.

I've seen museum exhibits based on fictional entertainment franchises before, but the first thing that I noticed about the Pokemon exhibit, was how the visitor is immersed between two worlds, the real world, and the fictional Pokemon world.  The signage talks to you from both places, so you can imagine yourself as a real Pokemon trainer in that fictional world part of the time.  The biggest example of this was how the exhibit acknowledges the difference in the meaning of the word "evolution" between the real world and the Pokemon world.  They explain how actual evolution is a process that typically takes many generations or millions of years to observe and how fossils play a part in our understanding of it.  Then they compare to how in pokemon "evolution" is more like metamorphosis, individual animals changing their form drastically at specific points during their life.  Below is a translation from the signage for this section of the exhibit.

"As your Charmander accumulates experience in battles and other tasks, it evolves into a Charmeleon, and eventually into a winged Charizard.  It becomes a different kind of Pokemon with a very different appearance, but as an individual it is still the same you got from Professor Oak.  It may sound a lot like 'growth' in our world, although the change is perhaps more than just growth, and it is seemingly not related to the passage of time.

In our world, 'evolution' doesn't happen to an individual, but occurs as a group, over the course of generations.  For example, we say 'life evolved from fish to amphibians, and eventually began to live on land' to describe an evolutionary course.  But this does not mean that one fish acquired feet instead of fins and began to walk on the ground.  First, amongst fish there were some individuals that had 'slightly harder fins'. These were advantageous for survival in certain circumstances, so later generations had more individuals with those 'slightly harder fins'.  This was repeated over a long enough time to reach individual obtained 'much harder fins' that we would consider a different species."

This was probably my favorite piece of signage in the museum for educational value.  I love how gracefully they explain real evolution compared to how it works in the Pokemon games.

Lastly the gift shop was full of all sorts of exclusive goodies.  This was of course dangerous for my wallet.  The haul you see her was me showing restraint.  I especially love the skeletal art keychains.  

Paleontologist Pikachu plush, skeleton keychains of Aerodactyl and Aurorus, postcards, sticker, and magnet of Hitoshi Ariga's art, and finally a break apart chocolate bar of one of several randomly assorted prehistoric pokemon. (a popular candy in Japan, normally featuring real dinosaurs) This haul was me showing restraint. Still kinda wish I grabbed the Rampardos plush and the fossil Pokemon bandana.

Overall I'm thrilled I finally got to visit this delightful exhibit after only reading about it for years.  It was a once in a lifetime experience that my whole family thoroughly enjoyed.  I especially appreciated how it was not short on real fossil displays or actual science education, despite the Pokemon theme, so even people who aren't fans of the franchise could enjoy it.  I highly recommend visiting for any Pokemon or paleontology fan.  If you want more prehistoric Pokemon content from me or want more info on the various Pokemon mentioned in this post, make sure to check out when I broke down which real animals all the prehistoric Pokemon are based on in three parts 1 through 3.  Here, here, and here.

The walls of the gift shop were covered in skeletals of fossil Pokemon. I love them.


Sunday, November 26, 2023

Venetoraptor: Beast of the Week

This week we'll be checking out a recently described creature that looks as natural in a space fantasy franchise as it does in the late Triassic.  Say hello to Venetoraptor gassenae!

Venetoraptor gassenae life reconstruction in watercolors by Christopher DiPiazza.

Venetoraptor was a small archosaur(reptile group that includes dinosaurs, pterosaurs, and crocodilians) that lived in what is now southern Brazil during the late Triassic period, between 237 and 227 million years ago.  From beak to tail, it measured a little over three feet (96cm) long.  It's genus name translates to "Vale Veneto Hunter/Thief" after the the area of Brazil near where its fossils were found, Vale Veneto.  

Venetoraptor was a member of the lagerpetid family of archosaurs.  Lagerpetids were generally small animals with proportionally long, slender limbs that exhibited fully erect posture, like dinosaurs and pterosaurs have.  Many were quadrupeds, but some, like Venetoraptor, were thought to walk on their hind limbs.  Lagerpetids are also interesting because they at one time were thought to be the group that gave rise to the first dinosaurs.  It is more recently thought, however, that lagerpetids were actually more closely related to pterosaurs.  It is plausible that lagerpetids, like Venetoraptor, were covered in feather-like structures in life, since both pterosaurs and some dinosaurs are also known to have had them.

3D printed Skeletal mount of Venetoraptor on display at the Bernardino Rivadavia Natural Sciences Museum in Buenos Aires.  photo credit: CONICET

Venetoraptor had a hooked beak, similar to modern birds of prey, on the tip of its mouth.  Unfortunately the rest of its jaws past the tips were never found so it is unclear if it had teeth or not.  It also would have had proportionally large eye sockets, suggesting it had sharp eyesight in life.  The hooked beak suggests Venetoraptor may have been a meat eater, hunting insects and other small animals, but at this point its exact diet is still mostly guesswork.  

Venetoraptor possessed long slender limbs, its legs were especially long, suggesting it was capable of bipedal locomotion in life.  It also had noticeably long, hooked claws, leading some think it may have been a good climber, possibly spending considerable time in, or even living in trees.  

I'm just going to come out and say it.  Venetoraptor looks like the Kowakian Monkey-lizards from Star Wars.

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

References

Kammerer, Christian F.; Nesbitt, Sterling J.; Flynn, John J.; Ranivoharimanana, Lovasoa; Wyss, André R. (2020-07-28). "A tiny ornithodiran archosaur from the Triassic of Madagascar and the role of miniaturization in dinosaur and pterosaur ancestry"Proceedings of the National Academy of Sciences117 (30): 17932–17936.

Müller, R. T.; Ezcurra, M. D.; Garcia, M. S.; Agnolín, F. L.; Stocker, M. R.; Novas, F. E.; Soares, M. B.; Kellner, A. W. A.; Nesbitt, S. J. (2023). "New reptile shows dinosaurs and pterosaurs evolved among diverse precursors"Nature620 (7974): 589–594.

Sunday, October 29, 2023

Medusaceratops: Beast of the Week

 Medusaceratops lokii was a plant-eating dinosaur that lived in what is now Montana, USA, during the Late Cretaceous period, between 78 and 77 million years ago.  Medusaceratops measured about twenty feet long from beak to tail and was a member of the ceratopsian family of dinosaurs, most known for their horns, beaks, and frills. The genus name, Medusaceratops, translates to "Medusa Horn Face" in reference to the horns over the eyes and around the frill of this dinosaur, which curved downward, and were almost serpentine in shape.  This reminded paleontologists of the mythical creature called a gorgon, the most famous of which was named Medusa, who had snakes for hair and could turn people to stone if they looked at her.  The species namelokii, is in reference to Loki, the Norse god of trickery.  This is because the bones of Medusaceratops were believed to have belonged to other, already known ceratopsian dinosaurs for years, and in a sense, tricked paleontologists into thinking it was a different taxa before finally being recognized in 2010.

Medusaceratops life reconstruction by Christopher DiPiazza.

So why did Medusaceratops have those horns, anyway?  Unlike the horns of some other ceratopsians, which face up our outwards, this dinosaur's horns point downwards.  Unless it was fighting the monsters from Tremors, I doubt they would have been much good as weapons against predators.  Part of me still thinks that the horns, despite this, still could have deterred a predator from hurting vital areas on Medusaceratops' body, like the eyes or neck, simply by just being in the way.  This idea doesn't really hold up since there were so many different kinds of ceratopsains, each with unique horn arrangements, however.  If they were purely for defense, we would more likely see ceratopsian horns converge to a defensive arrangement across the family.  The more likely answer to these horns is that they were display adaptations, meant to intimidate and/or impress members of the same species.  If a would-be predator happened to break at tooth or two on a horn in a failed attempt to hunt Medusaceratops then it was icing on the ceratopsian cake...which that predator would never get to taste.

Medusaceratops skeletal mount on display at the Wyoming Dinosaur Center.

Medusaceratops was originally thought to be the oldest known chasmosaurine ceratopsian dinosaur on the fossil record.  Chasmosaurine ceratopsians typically had longer horns over their eyes, and proportionally long frills.  Chasmosaurus, Triceratops, Mercuriceratops, Coahuilaceratops, and Vagaceratops are all examples of other chasmosaurines.  More recently found material and further inspection of its bones, however, reveal that Medusaceratops was actually a member of the centrosaurine group of ceratopsians, known for having proportionally shorter frills and taller snouts, like Styracosaurus, StellasaurusWendiceratops, and Nasutoceratops.  

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

References

Kentaro Chiba; Michael J. Ryan; Federico Fanti; Mark A. Loewen; David C. Evans (2018). "New material and systematic re-evaluation of Medusaceratops lokii (Dinosauria, Ceratopsidae) from the Judith River Formation (Campanian, Montana)". Journal of Paleontology92 (2): 272–288.

Ryan, Michael J.; Russell, Anthony P., and Hartman, Scott. (2010). "A New Chasmosaurine Ceratopsid from the Judith River Formation, Montana", In: Michael J. Ryan, Brenda J. Chinnery-Allgeier, and David A. Eberth (eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium, Indiana University Press, 656 pp.

Tuesday, September 26, 2023

Dakotaraptor: Beast of the Week

This week we will be revisiting an unfortunately very confusing dinosaur.  Let's check out Dakotaraptor steini.  Dakotaraptor was originally published on in 2015 and was claimed by the head author to be a very large dromaeosaur, in the same family as Deinonychus and Velociraptor.  It would have lived in what is now South Dakota, United States, during the very late Cretaceous Period, 66 million years ago.  From snout to tail it was estimated to measure about eighteen feet long, which would have made it one of the largest dromaeosaurs known. Other dinosaurs that would have been from the same environment include Tyrannosaurus, Triceratops, Pachycephalosaurus, Edmontosaurus, Anzu, and Acheroraptor.  The genus name, Dakotaraptor, translates to "Dakota Thief/Hunter" in reference to where it was found.

Life restoration of what the creature associated with Dakotaraptor MAY have looked like if it was indeed an unenlagiine. (I included it's other misidentified parts too if you know what to look for!)

Since the initial discovery and publication, many the fossils associated with Dakotaraptor have, under more close examination, turned out to be from other animals.  The original bones weren't found articulated in any sort of death position, but were more jumbled up in what likely used to be the bottom of a body of water, so it makes sense that multiple different dead animals ended up there over time and were eventually fossilized.  Some of the bones turned out to belong to the large oviraptorosaur, Anzu, as well as Tyrannosaurus, and even a prehistoric Soft-shelled turtle, called Axestemys.  

Photograph of what was originally thought to be the "killer" retractable toe claw of Dakotaraptor that has since been recognized as possibly being from a Tyrannosaurus hand.


That being said there are still a few bones that were associated with Dakotaraptor that as of now appear to be from some kind of large dromaeosaur.  More recent peer reviewed research suggests Dakotaraptor may actually belong to the unenlagiine branch of dromaeosaurs, the group known for having very long narrow snouts, based on what little material there is.  Until these bones can be formally studied further, we may never know for sure.

References

Arbour, V.M.; Zanno, L.E.; Larson, D.W.; Evans, D.C.; Sues, H. (2015). "The furculae of the dromaeosaurid dinosaur Dakotaraptor steini are trionychid turtle entoplastra"PeerJ3: e1957.

DePalma, Robert A.; Burnham, David A.; Martin, Larry D.; Larson, Peter L.; Bakker, Robert T. (2015). "The First Giant Raptor (Theropoda: Dromaeosauridae) from the Hell Creek Formation.".Paleontological Contributions (14).

Jasinski, Steven E.; Sullivan, Robert M.; Dodson, Peter (2020-03-26). "New Dromaeosaurid Dinosaur (Theropoda, Dromaeosauridae) from New Mexico and Biodiversity of Dromaeosaurids at the end of the Cretaceous"Scientific Reports10 (1): 5105.

Hartman, S.; Mortimer, M.; Wahl, W. R.; Lomax, D. R.; Lippincott, J.; Lovelace, D. M. (2019). "A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight"PeerJ7: e7247.