Heterodontosaurus: Beast of the Week

This week we will be checking out a little dinosaur with very interesting teeth, check out Heterodontosaurus tucki!

Heterodontosaurus life reconstruction by Christopher DiPiazza.  A related kind of dinosaur was discovered with long, quill-like structures growing from its back.  What you see on the backs of these guys is based on that, but nothing like that has been discovered on Heterodontosaurus, itself, yet.

Heterodontosaurus was a plant-eating dinosaur that lived in what is now South Africa, during the Early Jurassic Period, between 199 and 196 million years ago.  It was only a little over three feet long from beak to tail, and would have been able to run quickly on its hind legs when alive.  Its genus name translates to "different kinds of teeth lizard/dinosaur" because unlike many reptiles (not all!) which have only one kind of tooth throughout the mouth. Heterodontosaurus had three.  Heterodontosaurus was an ornithischian dinosaur, defined by the shape of its hips, so it belonged to the same major group as the ceratopsians, thyreophorans, and ornithopod dinosaurs.

Heterodontosaurus skeletal display at the American Museum of Natural History in New York City.

Heterodontosaurus' skull is interesting to behold for the first time.  In the front of the snout, it had a beak, which could have been good for clipping vegetation.  Just beyond this beak, inside the front of the mouth it had pointed teeth, which may have been for stripping leaves or other foliage off of stalks.  Just past those, are the teeth that make Heterodontosaurus stand out, which were long, and tusk-like.  We are not exactly sure what these teeth would have been for.  Some have proposed that Heterodontosaurus was actually an omnivore, and could have used these teeth for killing prey.  It also likely used them for show, or possibly combating rivals of the same species.  Modern herbivores like the Water Deer, from China, have tusks very similar to this, which are used for display and fighting rivals.  However, it should be important to note that there has been a skull of a juvenile Heterdontosaurus unearthed that has long, canine-like teeth just like the adults had.  This supports the idea that these teeth were not a sexual display adaptation, since they weren't exclusive to adults.  In the back of the mouth Heterodontosaurus had small, packed teeth for mushing up vegetation.

Chines Water Deer.  Adult males of this species have the longest canines for show and combat.  Heterdontosaurus' long tusks appear to not be exclusive to adults, however.

Heterodontosaurus had five fingers on each hand, digits two and three being the longest, which were strong and could have been for grasping vegetation while foraging.  The arms were relatively long, but wouldn't have allowed for quadrupedal locomotion. (walking on all fours)  Heterdontosaurus also had long slender legs with bird-like joints, suggesting it was a fast runner when alive.  This probably was its main defense against predators in its time.

That is all for this week!  As always comment below or on the facebook page!

References

Butler, Richard J.; Porro, Laura B.; Norman, David B. (2008). "A juvenile skull of the primitive ornithischian dinosaur Heterodontosaurus tuckifrom the 'Stormberg' of southern Africa". Journal of Vertebrate Paleontology 28 (3): 702. 

"Heterodontosaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 37.

Norman, D. B.; Crompton, A. W.; Butler, R. J.; Porro, L. B.; Charig, A. J. (2011). "The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962: Cranial anatomy, functional morphology, taxonomy, and relationships". Zoological Journal of the Linnean Society: no.

Santa Luca, Albert P.; Crompton, A. W.; Charig, Alan J. (1976). "A complete skeleton of the Late Triassic ornithischian Heterodontosaurus tucki". Nature 264 (5584): 324.

SciCafe: Inside Bats

At the American Museum of Natural History, every month an event, called SciCafe, is hosted where guests can come to the museum after hours, are served dinner and drinks (for a small fee) and are treated to an exciting lecture by one of the museum's staff about their research!  It is a great way to spend a weekday night if you have the time.

This past week I had the pleasure of attending one of these events where the topic of the night was bats.  Curator of Mammalogy, Dr. Nancy Simmons, and Postdocotral Research Fellow, Dr. Abigail Curtis, shared their most recent research on the inner workings of the earth's only flying mammal.

What made this lecture particularly interesting to me, and I'm sure a lot of people, is the fact that Dr. Simmons and Dr. Curtis, are using modern technology, like CT scanners, to find out new information about specimens of bats, here at the museum, that were collected over one hundred years ago.  A dead bad, preserved in formaldehyde, can be scanned without leaving its jar, and yield a three-dimensional image of its insides.   One specimen, in particular, turned out to have been collected on one of Theodore Roosevelt's expeditions!  It's great to know that specimens in the museum are still proving their worth after so many years.

Dr. Curtis and Dr. Simmons answering questions after their lecture.  A CT scan of a pair of cochlia (part of the inner ear) of a bat floats around on the screen behind them.  Dr. Curtis affectionately referred to cochlia of certain species of bat as "cinnamon bun-shaped" which made me hungry.

Bats are interesting because they are so specialized as a group, yet at the same time, were one of the first kinds of mammals to distinguish themselves after the great extinction that wiped out most of the dinosaurs.  The oldest bat fossil ever discovered is about 52 million years old, so it was around not much longer after the Cretaceous ended, but still was a true, flying bat.  So far, no transitional fossil between ancestral land mammal and a flying bat has ever been discovered.  this means that the ancestors of bats must have evolving in the direction they were even closer to the Cretaceous.  Since then, bats have had a LOT of time to radiate into the thousands of species that we see around us today. (Yes, thousands.  In fact, there are more known species of bat alive than any other major kind of mammal.)  I learned from Dr. Curtis, that night, that within several hundred square feet of rainforest in some parts of Central and South America, there can be as many as one hundred different species of bat living there!  That's a lot of specific niches.

The Painted Bat (Kerivoula picta) which is native to Thailand, embraces the whole Halloween Stereotype it seems.  Photo credit: Bob Cornes.  This beautiful species was features briefly in the opening of the lecture.

Small, differentiating features among different kinds of bats is what this lecture was mostly about.  Thanks to new technology, we can now see features about a bat's skull (which can be about the size of your fingernail, depending on the species.) that we would never have noticed before.  Minute variations in the structure of the nasal cavity, ear bones, and teeth of a bat can tell us a lot about how exactly they are living. 

My favorite species of bat is the Greater Bulldog Bat (Noctilio leporinus) because we share the same taste in seafood...or riverfood I suppose.  These guys use echolocation to detect ripples made by fish on the water's surface, then crab them out of the water with their hooked claws.  The minor differences in the shapes of a bat's nasal cavity, and inner ear, may drastically affect their sensort abilities, and therefore how and what they exploit as a food source.  This could be part of the reason why there are so many different species, many times coexisting in the same habitat.

One more really interesting fact I learned that night was that out of all the other major kinds of mammals alive today, according to DNA testing, bats are most closely related to...the order that includes pigs and goats, called artiodactyla.  Not, insectivores, like shrews, and not even primates...pigs, goats, deer, cows, giraffes...those guys.  Evolution never ceases to surprise me.

"MOOOOO!"

For more information about SciCafe and this lecture click here! 

Titanis: Beast of the Week

Titanis walleri was a large, flightless bird that lived in what is now southern North America between the late Pliocene and early Pliestocene epochs, between 5 and 2 million years ago.  The largest found Titanis towered at over eight feet tall, but there were many smaller individuals found, as well, suggesting sexual size dimorphism.  It's beak, which was hooked at the tip and sharp on the edges, suggests it was a meat-eater.  When Titanis would have coexisted with many famous prehistoric mammals, like saber-toothed cats, giant sloths, Glyptodon, mammoths, and even early humans.  The name, Titanis, translates to "titan" which means "giant", and is also the name of the first Greek gods (the generation before Zeus)  It is an appropriate name because this bird was HUGE.

Titanis walleri about to swallow a young capybara.  Painting by Christopher DiPiazza. 

Titanis was a member of the extinct group of large, predatory, flightless birds, called phorusrachidae, but their nickname, "terror birds", is cooler sounding.  There were a few kinds of known terror birds that have been discovered and described, but Titanis was the largest, and it was also the only known member of this family to have lived in North America.  All of the others were found in South America, which is where Titanis' lineage likely migrated from for reasons that are still a mystery to paleontologists. 

Titanis skeletal mount on display at the Florida Museum of Natural History.

Phorusrachids do have one very close relative that is alive today, called the Seriema.  Seriemas belong to the order of birds, called cariaformes, which includes the terror birds.  The modern seriema, although much smaller than its ancient cousins, gives us many clues as to how birds like Titanis may have lived.  For one thing, seriemas are also predators, specializing in killing smaller prey, like lizards and snakes by grabbing them in their beaks and beating the poor little creatures to death against the ground.  They also will use their feet to stun or immobilize prey.  In fact, the second toe on each of their feet houses an enlarged "killer claw" just like their even older, more distant cousins, the dromaeosaurids, like Velociraptor and Deinonychus!  Both seriemas and Titanis also have similar wrists and hands (wings), which could flex to a certain degree, but from what we see in seriemas, have no specific purpose that we know of.

Red-legged Seriema with an enlarged picture of the foot, showing the enlarged talon.

Titanis also had sharp, curved claws on its toes, which no doubt could have helped it pin down prey, but its major weapon was probably its head, which was armed with a massive, hooked beak.   There are a few schools of thought as to how Titanis used its beak.  The most popular idea is that the great bird would have swung its head at its prey, like a pickaxe, nailing it with the hooked end to kill it or immobilize it. It then may have pinned the unfortunate creature down with its strong claws as it used the hooked tip of the beak, paired with the sharp edges to rip off pieces of the likely still living prey to eat like a fork and knife. (Check out the video below of the Eurasian Hawk I work with using this method on a dead mouse I gave her.)  If the prey was small enough, Titanis likely would have swallowed it whole, which is something living predatory birds also do.  Another interesting possibility is that Titanis could have used its beak to hold smaller prey and beat them against the ground like its modern relative, the seriema does.

Titanis is an amazing example of convergent evolution, recycling a successful design more than once in the same major lineage of animals.  Titanis, as you know, was a bird, and therefore a kind of theropod dinosaur.  Unlike other large, flightless theropods, like Tyrannosaurus, however, Titanis did not live during the Mesozoic, but much later after the meteorite that wiped out most of its ancient kin hit the earth.  Furthermore, Titanis did not evolve directly from these large predatory dinosaurs, but rather from smaller birds that were probably capable of flight.  Dinosaur evolution is complicated!

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

References

Alvarenga, H. M. F.; Höfling, E. (2003). "Systematic revision of the Phorusrhacidae (Aves: Ralliformes)". Papéis Avulsos de Zoologia 43 (4): 55–91.

Baskin, J. A. (1995). "The giant flightless bird Titanis walleri (Aves: Phorusrhacidae) from the Pleistocene coastal plain of South Texas". Journal of Vertebrate Paleontology 15 (4): 842–844.

MacFadden, Bruce J.; Labs-Hochstein, Joann; Hulbert, Richard C.; Baskin, Jon A. (2007). "Revised age of the late Neogene terror bird (Titanis) in North America during the Great American Interchange" (PDF). Geology 35 (2): 123–126.

Mosaiceratops: Beast of the Week

This week we will be checking out a newly discovered dinosaur that was published on just last week!  Enter Mosaiceratops azumai!

Mosaiceratops was a small, plant-eating ceratopsian dinosaur that lived in what is now China during the Late Cretaceous, between 92 and 78 million years ago.  From beak to tail it only measured a bit over three feet long and would have eaten plants.  The name "Mosaiceratops" translates to "Mosaic Horned Face" because it had features about its anatomy that are present in more than one group of ceratopsians...like a mosaic...which is made of different kinds of tiles.

Mosaiceratops life reconstruction by Christopher DiPiazza.

Mosaiceratops belongs to the group of dinosaurs referred to as ceratopsians.  The most famous of these is Triceratops, but there were a lot more.  Of these beaked and frilled dinosaurs, there is a lesser-known branch, called the basal neoceratopsians.  These guys were more evolved than say, Yinlong, which as far as we know is the oldest member of the ceratopsian family tree, but still not in the same specific group as the really large members with huge horns, like Triceratops and Styracosaurus.  The basal neoceratopsians tended to be small, could walk on their hind legs or on all fours, and had rather short frills.  Aquilops is a good example of a basal neoceratopsian.  Mosaiceratops, although a member of this group, had some odd characteristics about it still.  The most prominent was the fact hat it didn't have any teeth in the front part o fits jaw, just beyond the beak, called the premaxilla.  In other members of its group, there are small, pointed teeth present there, possibly to help rake in vegetation easier, but not in Mosaiceratops!  In fact, other than the extremely large ceratopsids, like Triceratops, the very early, and more separated group of ceratopsians, called the psittacosaurs, are also known to have no teeth in that part of the mouth.  But Mosaiceratops doesn't appear to be one of them, either.  This is why it is called a mosaic-dinosaur, or a combination of different traits.  It helps scientists map out the evolution of ceratopsian dinosaurs that much more, by making it that much more complicated!

Fossil material found of Mosaiceratops.  You can see the underside of the jaws in the upper left of the photo.

When alive Mosaiceratops would have used its sharp, curved beak to clip vegetation which it would process in the back of its mouth with its small teeth.  Its lower jaw was especially robust, suggesting it could bite down extremely hard if it wanted to.  It also had relatively long arms, each tipped with five fingers, three of which had claws, which may have aided it in manipulating food, or maybe even digging in the dirt of roots or possibly invertebrates to eat for extra protein.  The eye sockets of Mosaiceratops would have been very large, suggesting it had decent vision.

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

References


Zheng, W., Jin, X., and Xu, X. 2015. A psittacosaurid-like basal neoceratopsian from the Upper Cretaceous of central China and its implications for basal ceratopsian evolution. Scientific Reports 5: 14190.

Ankylosaurus: Beast of the Week

This week let's check out an extremely famous, yet not so well known, dinosaur.  Enter Ankylosaurus magniventris!

Ankylosaurus was a plant-eating dinosaur that lived in what is now the western United States during the very end of the Cretaceous Period, between 68 and 66 million years ago.  It was a member of the family, ankylosauridae, which is named after it.  Ankylosaurids are characterized by having thick, bony pieces of armor, called osteoderms, in their skin.  Osteoderms are found in other animals, too, but the ankylosaurids had the most and the toughest!  Some parts of ankylosaurid armor were fused together, like on the head or the giant plate over the hips, called the sacral shield.  In fact, the name, "Ankylosaurus" translates to "fused lizard/reptile" because parts of its skeleton were reinforced in this manner.  Ankylosaurus was one of the largest members of this family, with adults estimated to have measured about twenty feet long from beak to tail.  Some paleontologists, however, have estimated even larger sizes, closer to thirty feet.  (No complete skeleton has been found so its true full size is uncertain.)

Ankylosaurus magniventris takes a midday nap.  Reconstruction by Christopher DiPiazza.

Ankylosaurus, although by far the most popular of the ankylosaurids, is not the most well-known.  In fact, we still don't know what the entire skeleton looks like exactly, including the sacral shield.  (We assume it had one based on other, related ankylosaurids.)  More often than not, especially when it comes to pop culture and plastic toys (cheaper ones at least) when you see a dinosaur labelled "Ankylosaurus" the creature you are looking at is mostly based on Euoplocephalus, a closely related, more completely known kind of ankylosaurid.

This toy, labelled "Ankylosaurus", although beautifully detailed...is mostly modeled after other ankylosaurids, mainly Euoplocephalus.  Actual Ankylosaurus would have a different club and different armor.

Ankylosaurus had an interesting-shaped skull.  It's snout, which was tipped with a broad beak, sloped downwards and the armor above it was so wide that its nostrils would have been very narrow and faced sideways, under it.  It had two shallow, triangular horns facing backwards on both sides of the back of its skull, and two downwards and sideways facing horns attached to its jugals ("cheek bones")  The overall skull was wider than it was long.  In the back of its mouth, Ankylosaurus possessed a series of small, leaf-shaped teeth, which would have been ideal for shredding plant material.  Like its relative, Euoplocephalus, it is likely Ankylosaurus was not a picky eater, and just scarfed down any vegetation that was in front of it.  We assume this based on the fact that its beak was broad, rather than narrow.

Side and dorsal view of the skull of Ankylosaurus, which is now on display at the American Museum of Natural History in New York.

The armor of Ankylosaurus was simple, but would have been effective in protecting it against predators, and possibly rivals of its own species.  Unlike relatives, like Euoplocephalus, which had some pointed, spike-like osteoderms, most of Ankylosaurus' armor consisted of smooth, flat osteoderms.  They varied in size greatly and to be honest, paleontologists don't know exactly how they were arranged on the dinosaur's body, but they have a pretty good idea based on related ankylosaurids that fossilized better.  This armor was actually not as heavy as it looked, but would have still been extremely strong in life.  Under a microscope, one would find that these osteoderms looked like a network of bony fibers with hollow spaces between.  This allowed the armor of Ankylosaurus to remain strong, but also be light.

Ankylosaurus tail club on display at the American Museum of Natural History in New York.

 Of course, we need to talk about Ankylosaurus' signature tail.  This dinosaur's tail was thick and muscular at the base, and became stiff more towards the tip, thanks to ossified tendons running along the vertebrae, which had a mass of solid bone at the end of it.  This tail club could have been swung from side to side with devastating force and may have been used as a defense weapon against potential predators, like Tyrannosaurus.  I should also note that when I say "solid bone" the tail still varied in density.  The outermost layer of the club was dense and heavier, but the inside of it was made of lighter, spongier bone.  This would have allowed the tail to have been light enough to carry, but still dangerous.

That is all for this week!  As always feel free to comment below or on our facebook page!  Also special thanks to Dr. Victoria Arbour for her consultant work as I made the life painting and info on this page.

References

Arbour, Victoria Megan. "Estimating Impact Forces of Tail Club Strikes by Ankylosaurid Dinosaurs." PLoS ONE 4.8 (2009): n. pag. Web.

Arbour, V. M.; Currie, P. J. (2015). "Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs". Journal of Systematic Palaeontology.

Carpenter, K. (2004). "Redescription of Ankylosaurus magniventris Brown 1908 (Ankylosauridae) from the Upper Cretaceous of the Western Interior of North America". Canadian Journal of Earth Sciences 41: 961–86.

Scheyer, T. M.; Sander, P. M. (2004). "Histology of ankylosaur osteoderms: implications for systematics and function". Journal of Vertebrate Paleontology 24 (4): 874–93. 

Vickaryous, M. K., Maryanska, T.; Weishampel, D. B. (2004). "Ankylosauria". In Weishampel, D. B.; Dodson, P.; Osmólska, H. The Dinosauria. University of California Press. pp. 363–92.

Carnotaurus: Beast of the Week

This week we shall be checking out Carnotaurus sastrei!  Carnotaurus was a meat-eating dinosaur that lived in what is now Argentina during the Late Cretaceous period, between 72 and 70 million years ago.  The name, Carnotaurus, translates to "Meat-eating Bull" in reference to its diet and the fact that it had two large horns over its eyes.  These horns are just one of the characteristics that make this incredible dinosaur one of the most stand-out, unique theropods known to science.  Carnotaurus is considered a very late member of the group of theropods called ceratosaurs, of which was one of the largest members, estimated to have measured between twenty five and thirty feet long from snout to tail. (A good part of the tail was never discovered so we don't know exactly how long it was.) Ceratosaurus and Masiakasaurus were also ceratosaurs.

Carnotaurus dueling life reconstruction by Christopher DiPiazza.

Carnotaurus has done nothing but slowly and steadily gain popularity since its discovery in 1984.  Like Spinosaurus and Velociraptor, Carnotaurus has gained its place as a well-known, mainstream predatory dinosaur next to the throne of Tyrannosaurus, thanks to the fact that it just looks so different.  It was the main (terrifying) villain in the 2000 Disney movie, Dinosaur, a regular antagonist in the cancelled television show, Terra Nova, and was featured heavily in the last two Jurassic World movies as well as the spinoff Netflix show, Camp Cretaceous.  

The robust horns are probably Carnotaurus' most notable feature.  Growing out over the eyes, and at almost six inches long, it is unlikely they aided Carnotaurus in hunting or killing prey, but rather played a part when dealing with members of its own species.  The horns were flat on the top, extending the surface area of the top of the skull and would have been surrounded by a layer of keratin in life, making them longer than what can be observed on the fossilized skull alone.  It is possible Carnotaurus rammed each other, like modern muskox, or maybe shoved each other in the sides/flanks.  

In order to support a robust skull with horns, Carnotaurus had a unique neck.  Unlike the necks of many other large predatory theropods, which were relatively short, in order to support proportionally large heads, Carnotaurus had unusually long, but thick neck.  Its skull was also proportionally smaller compared to the rest of its body, which would have made using those horns that much easier as a shoving, swinging, or ramming weapon.  Perhaps Carnotaurus engaged in these fights over territory, or males did over mating rights?  We really don't know for sure.  Even more frustrating is the fact that Carnotaurus is only known from one individual.  Now, this one individual is beautifully complete, but it's still only one.  This being said we have no clue if the horns of males and females differed in any way, which would help us get an idea of what they were for if we had that information.

Carnotaurus skeletal mount on display at the Bernardino Rivadavia Natural Sciences Museum in Buenos Aires, Argentina

The actual face of Carnotaurus was interesting, too.  Its snout was actually really short, and upturned.  It almost looks like a dinosaur version of a bulldog.  The face was also narrow, but the eyes faced forward, suggesting this dinosaur had strong binocular vision. (able to perceive depth effectively)

When it comes to Carnotaurus' jaw, there is some debate.  One group of paleontologists suggested that Carnotaurus would have been good at rapidly snapping its jaws, but didn't have a very powerful bite, at least not in the front of the snout.  Snapping jaws is something seen in predators that specialize more in hunting smaller prey.  The fact that Carnotaurus' jaws curved upwards, supports this, since it would be able to more easily grab smaller animals below it on the ground as they tried to run away.  The opposing idea about Carnotaurus' biting strategy is that it was actually more adapted to taking down larger prey, like other dinosaurs, and did so by using its upper skull, which was very tall, like a hatchet, swinging its head, mouth open, into the flanks of a sauropod or hadrosaur, and cutting into it with the blade-like teeth.  These paleontologists also found out that towards the back of Carnotaurus' jaws, it would have been able to bite down extremely hard compared to other dinosaurs, further supporting their claims that it was adapted for hunting large prey.  As strange and specialized as it may look, perhaps Carnotaurus was really a generalist hunter, using both of these strategies to take advantage of small or large prey, depending on what was available to it?

Close up of Carnotaurus' skull at the Dinosaur Discovery Museum in Wisconsin, USA.

Carnotaurus had small arms.  Really small arms.  Smaller than Tyrannosaurus' arms. (WHAT?) At least the arms of tyrannosarids, although small, still could have served a purpose since we know they were strong, had some mobility to them, and possessed claws.  Not the case with Carnotaurus.  Its arms not only were even smaller than those of the tyrannosaurids, they lacked hooked claws on their four tiny digits, and were even angled with the palms facing outwards, further restricting any sort of function they may have served...if any at all.  It is likely the arms of Carnotaurus were truly vestigial and had this dinosaur's lineage kept going for millions of years after its extinction, may have completely disappeared at some point!  Not to worry, however, with a head like that, who needs arms, right?

You know it's bad when T. rex, of all dinosaurs, is making fun of your short arms.

Sadly, Carnotaurus' feet and part of the lower legs were never discovered, but the parts that we do know of are pretty slender.  It may have been a fast runner in life from what can be told. (but again, only part of the legs are on the fossil record so we don't know for certain.)  What is interesting is that the head and neck of this dinosaur were so robust, but the rest of the body, especially the legs, were actually quite gracile.  Sadly, the environment of Carnotaurus is still mostly a mystery aside from plant life and some much smaller animals.  We really don't have many other good fossils from other dinosaurs from that area so we still don't have a very good idea of what Carnotaurus would have been hunting, but a good hypothesis is that whatever it was, it might have been able to run fast too!

Carnotaurus skin impression.  note the small scales surrounding those large craters where the osteoderms were.

Lastly, we know what the skin of Carnotaurus was like!  And it was cool!  Thanks to some beautifully preserved areas of rock around the skeleton that was dug up with imprints from the dinosaur's skin, we know that Carnotaurus' skin was scaly and pebbly, sort of like a crocodile's.  between these scales, it also had bony protrusions that would have stuck out like little knobby plates down its back and sides.  We call these structures osteoderms, and they are present in a lot of other kinds of dinosaurs and other reptiles like crocodilians, too.

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

References

Bonaparte, José F.; Novas, Fernando E.; Coria, Rodolfo A. (1990). "Carnotaurus sastrei Bonaparte, the horned, lightly built carnosaur from the Middle Cretaceous of Patagonia" (PDF). Contributions in Science (Natural History Museum of Los Angeles County) 416.

Candeiro, Carlos Roberto dos Anjos; Martinelli, Agustín Guillermo. "Abelisauroidea and carchardontosauridae (theropoda, dinosauria) in the cretaceous of south america. Paleogeographical and geocronological implications". Uberlândia (Sociedade de Naturaleza) 17 (33): 5–19.

Czerkas, Stephen A.; Czerkas, Sylvia J. (1997). "The Integument and Life Restoration of Carnotaurus". In Wolberg, D. I.; Stump, E.; Rosenberg, G. D. Dinofest International. Academy of Natural Sciences, Philadelphia. pp. 155–158.

Mazzetta, Gerardo V.; Fariña, Richard A.; Vizcaíno, Sergio F. (1998). "On the palaeobiology of the South American horned theropod Carnotaurus sastrei Bonaparte" (PDF). Gaia 15: 185–192.

Mazzetta, Gerardo V.; Christiansen, Per; Fariña, Richard A. (2004). "Giants and Bizarres: Body size of some southern South American Cretaceous dinosaurs" (PDF). Historical Biology 16 (2): 71–83.

Ruiz, Javier; Torices, Angélica; Serrano, Humberto; López, Valle (2011). "The hand structure of Carnotaurus sastrei (Theropoda, Abelisauridae): implications for hand diversity and evolution in abelisaurids". Palaeontology 54 (6): 1271–1277.

Therrien, François; Henderson, Donald; Ruff, Christopher (2005). "Bite Me – Biomechanical Models of Theropod Mandibles and Implications for Feeding Behavior". In Carpenter, Kenneth. The carnivorous dinosaurs. Indiana University Press. pp. 179–198, 228.

American Museum of Natural History: Tour of the Depths

As you might already know, I spent much of this past summer working at the American Museum of Natural History.  During my first week there I was put into contact with Wayne Callahan, through a mutual friend of ours, paleoartist, Larry Felder.  Wayne volunteers in the paleontology department at the museum, prepping and organizing the fossil collection.  He also conducts and publishes research on the fossils.  Wayne was kind enough to give me a tour of some of the behind the scenes areas of the paleontology department of the museum.

The American Museum of Natural History is one of the biggest museums in the world.  It is really impossible to see everything on display there in one day.  That being said, what is available to visitors is only a small fraction of what actually goes on at this place.  There are halls and halls of shelves upon shelves of specimens deep  in the depths of this museum that are only available to employees and volunteers there who study them.  This is because in addition to an educational facility for the public, the museum is also a leading research facility.  (not just in paleontology, either!)  Just so you know, the American Museum of Natural History has the most dinosaur fossils out of any museum in the world.  Don't ask exactly how many, because nobody there has bothered to count...but it's the most.  There are many fossils back there, many of which have Yet to be studied and some that haven't  even left their jackets since coming in from the field.  One could complete enough research to obtain a PhD back there without ever actually going into the field to dig anything up!  (Which would be kind of lame since fieldwork is pretty fun.)  If we never unearthed another new dinosaur fossil ever again, we'd still be discovering new things from this stash alone for a lifetime. 

Just a small part of the labyrinth of fossil shelves at the AMNH

Wayne and I quickly met up with paleontologist, Carl Mehling, who is the collections manager of vertebrate paleontology.  He showed me a lot of cool fossils, some of which have not been published on yet, so I can't post any pictures online.  (I didn't even take photos of those, actually.)  But there were still plenty of cool specimens I am allowed to share with you!

The American Museum of Natural History is probably most known for doing a lot of excavating of Mongolian dinosaur fossils.  The monumental Citipati that died while brooding its nest was found by the museum's team, as well as the very first known Velociraptor, to name a few.  When I was back there, they were in the process of getting two other beautifully-preserved Mongolian dinosaur skeletons cast.  These oviraptorids, called Khaan, nicknamed Romeo and Juliet, are interesting because they were discovered right next to each other with their hands touching.  Aw.

This is Romeo...or Juliet. (Not quite sure)  It's significant other was upstairs with a cast over it to make molds before they get shipped back to their original home, Mongolia.  Look at how beautifully complete it is! (Keep in mind despite the nickname there is no actual scientific evidence that these two dinosaurs were mates, or even of the opposite sex that we know of yet.  It's just a nickname.)

Possibly one of my favorite fossils back there was a chunk of Lambeosaurus tail that had all the skin still on it.  Fossilized dinosaur skin is extremely rare, but out of the few on the record that did preserve it, most are hadrosaurs.  One idea of why this is could be because hadrosaurs may have had thicker hides when compared to other dinosaurs.  It makes sense if you consider their contemporaries, like the ceratopsians and ankylosaurs had their more obvious defensive adaptations.

Section of Lambeosaurus tail with preserved skin.  Check out all those tiny mosaic-like scales!

Another cool fossil they had back there was a large slab of rock that included several Coelophysis.  This slab is from the same formation that yields most of the hundreds of Coelophysis skeletons on the fossil record, called the Ghost Ranch Formation.  It is believed the poor dinosaurs were in a dried riverbed when they were killed and buried underwater by a flash flood.  These kinds of fossils are particularly dear to me because I did much of my field work experience at the Redonda Formation, very close to the Ghost Ranch and from the same time period!

Slab containing several Coelophysis specimens at the AMNH

So the next time you visit the museum, remember that for every fossil that you see on display, there are many many more down below!  It's exciting to imagine what new discoveries are still to be made right under our noses!