Sunday, February 12, 2017

Bulbasaurus: Beast of the Week

This week we will be looking at a newly described reptilian relative of mammals.  Check out BulbasaurusBulbasaurus was a dicynodont, a wildly successful group of plant-eating reptiles that shared characteristics with mammals.  It lived during the late Permian, between 260 and 252 million years ago, in what is now South Africa.  From beak to tail it would have roughly measured two feet long...maybe a bit less.  (Only the skull has been found, which was about six inches long.)  The genus name, "Bulbasaurus", tranlsates to "bulbous reptile" in reference to the bony mass above its nose.  The species name, "phyloxyron", translates to "leaf razor", in reference to how it may have cut leaves to eat with its beak. 

Life reconstruction of Bulbasaurus, by Christopher DiPiazza.

Bulbasaurus, as stated above, was a dicynodont.  Dicynodonts were interesting reptiles that looked like a combination of a few different animals alive today.  I have heard many compare them to pigs...but I never really saw that.  They had proportionally large heads, and broad beaks.  Many kinds had two tusks protruding downwards from their top jaw.  They would have walked in a squat, semi-sprawling posture on four, stout legs.  So if I were to describe a dicynodond in terms of modern animals...I'd say just imagine a French Bulldog...with beak...yeah...yeah, that's perfect. 

Bulbasaurus was an important find because it was a member of the family within dicynodonts, called geikiidae.  Until its discovery, geikiids were only known from significantly later times in the Permian and Triassic.  Bulbasaurus sets the first geikiids back millions of years than what was previously thought, however.  Geiikid dicynodonts typically had particularly large, robust heads, curved beaks, and longer tusks, which Bulbasaurus had when compared to its contemporary family members. 
 

Bulbasaurus skull from the paper recently published by Christian Kammerer and Roger M. H. Smith.

SO WHAT ABOUT THAT NAME?!  Was Bulbasaurus named after the pokemon, Bulbasaur? It certainly looks similar.  In fact, Bulbasaur, the pokemon's design was almost certainly based off dicynodonts, as I explained in a post last year.  According to interviews with Dr. Christian Kammerer, one of the paleontologists who worked with, and lead author of the paper that describes Bulbasaurus, it's insisted the name is a coincidence, and it really is just in reference to it's nose...and the species name...."leaf razor" in reference to it's beak, despite the fact that any pokemon fan can tell you one of Bulbasaur's signature attacks is called razor leaf.  I guess we will just have to believe them just like you should just believe my illustration of Bulbasaurus in no way is in reference to Bulbasaur, the pokemon's, color scheme, nor is the pose and setting inspired by the artwork on Bulbasaur's first pokemon card...

Stop looking for things that aren't there!  Definitely no connection here.  Total coincidence.

References

Kammerer, C.F.; Smith, R.M.H. (2017). "An early geikiid dicynodont from the Tropidostoma Assemblage Zone (late Permian) of South Africa". PeerJ. 5. doi:10.7717/peerj.2913. ISSN 2167-8359.

Kammerer, C.F.; Angielczyk, K.D.; Frobisch, J. (2011). "A Comprehensive Taxonomic Revision of Dicynodon (Therapsida, Anomodontia) and Its Implications for Dicynodont Phylogeny, Biogeography, and Biostratigraphy". Journal of Vertebrate Paleontology. 31 (sp1): 1–158.

Saturday, February 4, 2017

Plateosaurus: Beast of the Week

This week we will be going over a well-known and popular dinosaur, Plateosaurus!

Plateosaurus was a plant-eating dinosaur that lived in what is now Germany, Switzerland, Greenland, and France, during the late Triassic Period, between about 214 and 210 million years ago.  As an adult it would have averaged about twenty feet long from snout to tail, although certain specimens suggest it was capable of growing even larger than that in some instances.  The name, "Plateosaurus" translates to "Broad-Build Lizard" most likely in reference to the dinosaur's robust bones.

Two rival Plateosaurus engelhardti duel for mating rights by Christopher DiPiazza.  The behavior was inspired by the intraspecies combat of many lizards and is purely speculation.

Plateosaurus is classified as a basal sauropodomorph, or "prosauropod".  These plant-eating dinosaurs were related to the much larger, and more iconic sauropods, like Brontosaurus and Apatosaurus, but tended to live in the late Triassic and early Jurassic periods.  In fact, a branch of basal sauropodomorphs actually gave rise to the first true sauropods.  Unlike sauropods, prosauropods typically walked on their hind legs.  Many of them, including Plateosaurus, were obligatory bipeds, meaning they could only walk on their hind legs, like modern birds, and other theropods.  If you think about it, certain dinosaurs were the ONLY animals in history to truly do this!  (Humans don't count.  We can crawl on all fours if we want to.)  That being said...Plateosaurus was likely able to walk on all fours when it was a baby, based on what we know about a close relative, Massospondylus, which were quadrupedal as babies, then became obligatory bipeds as they grew up.

Plateosaurus had a relatively long neck, which it would have used to help it feed on vegetation above and below it without without having to move its body much.  It had a long, almost rectangular skull, with the tip of its snout sloping slightly downwards.  Within the mouth it possessed many small, leaf-shaped teeth with serrations, which would have been ideal for eating plants, like horsetails, which lived at the same time as it.   The back of Plateosaurus' jaws also sloped downwards, implying there was more muscle there for biting through tough vegetation.

Plateosaurus mounted skeleton on display at the American Museum of Natural History in New York City.  The dinosaur would have likely walked with its tail above the ground in life, as this was mounted before that idea.

Plateosaurus also had robust, powerful arms, each tipped with five fingers.  The first three fingers possessed curved claws, the first digit's being the largest.  These claws may have helped to manipulate branches while feeding, defend against predators, or fight rivals of the same species. (or all three.)  The hind legs were also powerful, each foot ending in four long, broad claws.  The long, muscular tail would have helped Plateosaurus keep its balance as it walked around on its hind legs.

Left hand of Plateosaurus.  Note the large claw on digit 1.

Fortunately, Plateosaurus is known from many individual specimens, so scientists have been able to learn a lot about this dinosaur.  By looking at certain bones closely, it can be determined how an individual dinosaur was growing.  Plateosaurus, it turns out, went through a period of rapid growth when it was young, then slowing down when it reached a certain age or size.  However, the sizes of different individual Plateosaurus seemed to vary at the same age. For instance a sixteen-foot long Plateosaurus could have been the same age as an almost thirty foot Plateosaurus.  We see this today in modern reptiles and it depends on how many resources are available to animals as they are growing.  The more food an animal has, the larger and more rapidly it will grow.

Plateosaurus mounts on display at the University of Tübingen, in Germany.

Looking at the mobility of the ribs of Plateosaurus, and how they could change positions depending on if the dinosaur was inhaling or exhaling, it could also be hypothesized that this dinosaur was endothermic, like birds, and would have had the same kind of one-way breathing system that they do.  This form of respiratory system, only currently known today in birds and a few reptiles, makes it so that the animal is constantly taking in fresh oxygen with every inhale and exhale.  If humans could breathe like that track events would be a lot more intense!

That is all for this week!  Special thanks to Dr. Heinrich Mallison, who lent his expertise on Plateosaurus for the making of this post.

References

Creisler, Ben. "Plateosaurus: The Etymology and Meaning of a Name." Plateosaurus: The Etymology and Meaning of a Name. Dinosaur Mailing List, n.d. Web. 

Huene, F. von (1926). "Vollständige Osteologie eines Plateosauriden aus dem schwäbischen Keuper" [Complete osteology of a plateosaurid from the Swabian Keuper]. Geologische und Paläontologische Abhandlungen, Neue Folge (in German). 15 (2): 139–179.

Jaekel, O. (1911). Die Wirbeltiere. Eine Übersicht über die fossilen und lebenden Formen [The Vertebrates. An overview of the fossil and extant forms] (in German). Berlin: Borntraeger.

Mallison, H. (2010). "The digital Plateosaurus II: an assessment of the range of motion of the limbs and vertebral column and of previous reconstructions using a digital skeletal mount". Acta Palaeontologica Polonica. 55 (3): 433–458. 

Sander, M.; Klein, N. (2005). "Developmental plasticity in the life history of a prosauropod dinosaur". Science. 310 (5755): 1800–1802. Bibcode:2005Sci...310.1800S.

Tuesday, January 17, 2017

Shonisaurus: Beast of the Week

This week we will be looking a HUGE seabeast!  Make way for Shonisaurus popularis!  Shonisaurus was an ichthyosaur, in the same group as the more famous, Ichthyosaurus.  Like it's relatives, Shonisaurus' body was shaped similarly to that of a fish, despite the fact that it was an air-breathing reptile.  (This evolutionary strategy would pop up again, millions of years later with mammals in the form of whales.) Shonisaurus stands out because it was so large, measuring about 50 feet from snout to tail as an adult.  It lived in the ocean that covered what is now Nevada, in the USA, during the late Triassic Period, about 215 million years ago.  The name, Shonisaurus, translates to "Shoshone Mountain Lizard" in reference to the mountains in which it was found.  When alive, Shonisaurus would have eaten mollusks and fish.


Shonisaurus was an earlier form of ichthyosaur, so it did not possess all of the telltale characteristics you might see in later, more famous kinds, like Icthyosaurus.  For one thing, Shonisaurus presents no evidence of having possessed a dorsal flipper when alive, nor a full tail fluke.  So it wouldn't have had the distinct tuna-like profile other, later ichthyosaurs had.  Its lower flippers, that had evolved from walking limbs of its ancestors, were relatively long and narrow, while later relatives had more rounded ones.  One feature it had that did pass on to the rest of the ichthyosaur group was the fact that it had exceptionally large eyes, even proportional to its immense body size.  This suggests that Shonisaurus could see where there was little light, and may have spent at least part of its time in very deep waters.

Shonisaurus skull cast on display at the 2015 "Mega Dinosaur Exhibition" in Tokyo, Japan.

Shonisaurus was large.  It was one of the largest marine reptiles known to science, in fact.  So what and how did it eat?  Well, luckily, along with over thirty adult skeletons on the fossil record of this beast, paleontologists have also identified coprolites (fossilized poop) from it.  Turns out, according to the poop, Shonisaurus was eating squid, belemnites (like a squid but with an internal shell) and soft fish.  Interestingly enough, however, these prey items were all small, so it means that Shonisaurus must have been devouring huge quantities of them in order to grow and stay alive.  In order to better understand this, we can take a look at modern marine giants that prey on small animals.  Balene whales come to mind first, but as their description suggests, they had balene, an adaptation that helps them devour krill and other small prey in a very specific fashion.  Shonisaurus had small, almost nonexistent teeth that faced somewhat sideways in the mouth.  In fact, it appears that Shonisuarus' lineage was on its way to doing away with teeth altogether. (Which makes sense since there are many kinds of later ichthyosaurs that were toothless.)  I feel an even better modern analogue than whales would be the Basking Shark and Whale Shark.  These two kinds of sharks, in addition to also being very large, have no teeth in their mouths, but they can open them extremely wide as they filter feed on small prey.   Having been a reptile, Shonisaurus would have been able to open it's jaws relatively wide, as well, and could probably achieve similar feeding feats.

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

References

Kosch, Bradley F. (1990). "A revision of the skeletal reconstruction of Shonisaurus popularis (Reptilia: Ichthyosauria)". Journal of Vertebrate Paleontology10 (4): 512–514.

Mcmenamin, Mark A.s., Meghan C. Hussey, and Lydia Orr. "Ichthyosaur Coprolite With Nautiloid: New Data On The Diet Of Shonisaurus." (2016): n. pag. Web.

Nicholls, Elizabeth L.; Manabe, Makoto (2004). "Giant Ichthyosaurs of the Triassic—A New Species of Shonisaurus from the Pardonet Formation (Norian: Late Triassic) of British Columbia". Journal of Vertebrate Paleontology24 (4): 838–849.


Saturday, January 14, 2017

Mongolian Paleo Drama: Year in the Making

When I paint life reconstructions.  Unknown to the viewers, there is almost always a story behind every painting.  There are usually never any hints, or givaways, or any sign of a bigger picture, but as I'm working on the piece, I try to think of what that particular dinosaur or other prehistoric creature has gone through up until the exact second in time that I choose to capture it's image, as well as what might happen to it after that second is over.  In fact, if you were to ask most artists, they will probably tell you the same thing.  If you turn on Netflix and check out Bob Ross, you will see that he is a prime example of this, narrating his own story as he works along through his piece.  I strongly feel like if it wasn't for the artist's imagination and ideas behind the paintings, the products, themselves wouldn't have as much life.

That penguin, for instance...he's gonna make it.  He just is.

Well, sometimes I do give hints as to what is about to happen, or happened in the past of my subjects.  In the case that I'm about to show you, most people wouldn't have noticed there was a bigger story, because the two paintings in question were painted, and therefore shared with the world a year apart from one another.  But they are connected.  Let's look at the first one below.


It's my Therizinosaurus, a plant-eating theropod that lived in what is now Mongolia.  I was inspired by sloths while painting this fellow.  Back when I was working at zoos, I witnessed one of our male sloths, Eugene, fall asleep with a piece of lettuce in his hand.  Minutes later he woke up from his spontaneous nap to continue feasting.  I thought it would be cute to show a dinosaur doing something similar.  However, falling asleep can be dangerous, especially if you have predators...


Jump forward in time one year to November of 2016 when I finished this painting of a mother Tarbosaurus feeding her young.  Tarbosaurus was also from Mongolia and would have coexisted, and possibly hunted Therizinosaurus.  Now look closer at what exactly it is that she's feeding her baby...


That's right.  The hunk of meat that is being fed to her baby is the disembodied arm of Therizinosaurus, who likely was ambushed by the tyrannosaurid during his nap.  But there's a twist here.  Look closely at the mother Tarbosaurus again.  Not all that blood is coming from the disembodied arm.


Therizinosaurus managed to get a few hits in with his enormous claws before he was killed.  One nice slash to the face and another, deeper stab, to his attacker's neck and shoulder.  This Tarbosaurus is bleeding, and judging by the second wound, she might not have much time left.  Let's hope her baby can learn to hunt on his own quickly!

Sunday, January 1, 2017

Belonostomus: Beast of the Week

Today we will be checking out an often unfairly overlooked prehistoric fish.  Enter Belonostomus!  Belonostomus was a ray-finned, or bony fish, that lived in many parts of North America and Europe through much of the the Mesozoic Era.  It was wildly successful, the oldest species of this genus are from the Jurassic, about 150 million years old, and the youngest to date are all the way past the end of the Cretaceous, into the earliest part of the Paleocene, 59 million years ago!  Belonostomus on average tend to hover between a foot to almost two feet long from snout to tail, depending on the individual and species, of course.  On the other end of the size spectrum, there are Belonostomus specimens that are only about an inch long, which may have been adults.  (Unfortunately their skulls were too damaged to identify if they were, in fact adults or juveniles at the time of their deaths.)  The name, Belonostomus, translates to "Big Long Mouth" because...well, look at its mouth!

My life reconstruction of a still unnamed species of Belonostomus.  This painting was commissioned by Nathan VanVranken and featured with his recent research, presented at the 2016 Society of Vertebrate Paleontology meeting.

When alive, Belonostomus would have been a meat-eater, probably using its long, thin snout, lined with small, pointed teeth to shred smaller fish and other aquatic prey.  It's long, streamlined body, which was a characteristic of a fast-swimmer, also probably aided it in hunting.  Being medium-sized for a fish, it also probably had to worry about getting eaten by larger predators from both the water, like larger fish and marine reptiles, the air, in the form of pterosaurs, and probably even dinosaurs, like Baryonyx.

Belonostomus muensteri specimen on display at the Museum für Naturkunde in Berlin, Germany.

Modern Needlefish, which share a family with Belonostomus, look similar in many ways to their prehistoric relatives, and provide a decent modern analogue when imagining what Belonostomus might have been like when alive.

Close up of the teeth and jaws of Belonostomus sp featured in Van Vranken's 2016 research.

What is interesting about Belonostomus, is the fact that it is known from several really well preserved fossils, that range greatly in time, as stated above.  In fact, we can tell a lot about how both marine, and freshwater ecosystems were forming thanks to the presence of Belonostomus fossils.  And, yes, it is likely that Belonostomus could be either a fresh or salt-water fish, depending on the exact species.

References

Kogan, Ilja, and Martin Licht. "Erratum To: A Belonostomus Tenuirostris (Actinopterygii: Aspidorhynchidae) from the Late Jurassic of Kelheim (southern Germany) Preserved with Its Last Meal." Paläontologische Zeitschrift 89.3 (2014): 671. Web.

Van Vranken, N., Fielitz, C. BRIDGING THE GAP: THE BIOSTRATIGRAPHIC RECORD OF THE GENUS BELONOSTOMUS WITH NOTES ON NEW OCCURENCES IN TEXAS AND MEXICO. : Journal of Vertebrate Paleontology, Program and Abstracts, 2016. 242pp.

Woodward, Arthur Smith. "Genus BELONOSTOMUS, Agassiz." The Fossil Fishes of the English Wealden and Purbeck Formations (n.d.): 100-01. Web.

Sunday, November 27, 2016

Tarbosaurus: Beast of the Week

This week we will be checking out a huge tyrannosaurid.  Enter Tarbosaurus bataarTarbosaurus was a large meat-eating dinosaur that lived in what is now Mongolia and China during the late Cretaceous Period, about 70 million years ago.  The largest known individuals infer that they could have been just a little smaller than the largest known Tyrannosaurus, at about 39 feet long from snout to tail.  The genus name translates to "Alarming Lizard".  When alive, Tarbosaurus would have shared its habitat with (and maybe hunted) fellow theropods, Deinocheirus and Therizinosaurus, as well as the hadrosaur, Saurolophus.

Tarbosaurus and young...and lunch life (except lunch...lunch is dead) reconstruction by me.

Tarbosaurus was an extremely large tyrannosaurid, second largest known, right behind Tyrannosaurus.  These two genus are very similar in appearance at first glance, but key differences are present.  In fact, the two may not be as closely related to each other as they each might be to other kinds of tyrannosaurids that are known.  Starting at the head, Tarbosaurus had a laterally slim head.  It's eye sockets were primarily facing sideways, so it wouldn't have had much depth perception.  Thanks to scans of the inside of Tarbosaurus' skull, and looking at the shape of the brain case, scientists can infer that Tarbosaurus would have had a great sense of smell and hearing, but it was lacking in the sight department.  It likely would have hunted relying on its sense of smell mostly, unlike T. rex, which had more forward-facing eyes.  Tarbosaurus' teeth were sharp and curved for crushing and tearing flesh and bone, but weren't as proportionally large.  The actual jaws were less flexible than those of most other tyrannosaurids.  It possessed two extremely short arms with two fingers on each hand.  The arms of Tarbosaurus are proportionally the tiniest out of all tyrannosaurids. (Yes, they were even smaller than T. rex's.)  When examined more closely, it was discovered that the arms of Tarbosaurus commonly endured stress factors, meaning they likely weren't completely useless in life.  Some have suggested they aided in taking down prey but personally I feel they may have had some role when it came to mating.  We may never know!

Tarbosaurus skeletal mount on display at the Cosmacaixa Museum in Barcelona, Spain.

There are a relatively large number of Tarbosaurus specimens on the fossil record.  Among these are small juveniles.  Thanks to these individuals, we know that Tarbosaurus was proportionally leggier when it was little, bulking up as it aged.  The teeth were also more blade-like, and less robust when they were young.  Tarbosaurus probably filled different ecological niches as it aged, preying on smaller, faster prey when it was younger, and moving on to bigger game as it matured.  In fact, thanks to bite marks on bones, we can be fairly certain that an adult Tarbosaurus was eating at least Deinocheirus, the giant, flat-billed, ornithomimid.

Juvenile Tarbosaurus skull

Lastly, we have actually found clues as to what Tarbosaurus' skin was like...well at least parts of it.  A large individual had a small patch of skin (sadly we don't know exactly where because it was messed with by fossil poachers) that shows small, round scales.  These scales are each only about two millimeters wide in diameter.  In addition, a Tarbosaurus footprint was discovered, that showed evidence of being scaly as well.  Because of this evidence, many folks tend to argue that Tarbosaurus and its close relatives wouldn't have had feathers in life.  This is flawed, however, since even modern birds possess similar textures on their own feet.  Plus, other fossilized non-avian dinosaurs have been unearthed with evidence of both scales and feathers on other parts of their bodies than the feet.

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

References

Currie, Philip J.; Badamgarav, Demchig; Koppelhus, Eva B. (2003). "The First Late Cretaceous Footprints from the Locality in the Gobi of Mongolia". Ichnos. 10: 1–12.

Hurum, Jørn H.; Sabath, Karol (2003). "Giant theropod dinosaurs from Asia and North America: Skulls of Tarbosaurus bataar and Tyrannosaurus rex compared" (PDF). Acta Palaeontologica Polonica. 48 (2): 161–190.

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.

Saveliev, Sergei V.; Alifanov, Vladimir R. (2005). "A new study of the brain of the predatory dinosaur Tarbosaurus bataar (Theropoda, Tyrannosauridae)". Paleontological Journal. 41 (3): 281–289.

Tsuihiji, Takanobu; Watabe, Mahito; Tsogtbaatar, Khishigjav; Tsubamoto, Takehisa; Barsbold, Rinchen; Suzuki, Shigeru; Lee, Andrew H.; Ridgely, Ryan C.; Kawahara, Yasuhiro; Witmer, Lawrence M. (2011-05-01). "Cranial Osteology of a Juvenile Specimen of Tarbosaurus bataar (Theropoda, Tyrannosauridae) from the Nemegt Formation (Upper Cretaceous) of Bugin Tsav, Mongolia". Journal of Vertebrate Paleontology. 31 (3): 497–517.

Friday, November 25, 2016

Dinosaurs Among Us at the American Museum of Natural History

It's the day after Thanksgiving.  Many people cooked and ate a dinosaur last night.  This is nothing new.  I've been saying it for years.  Yet many people are still blindsided by the fact that birds are, in fact, literal dinosaurs.  (I just graded my tenth grade's vertebrate evolution quizzes...trust me.)  Finally, however, there is something that is available to ANYONE who happens to find themselves in New York City (at least until January) that not only educates, but shows proof of this amazing connection between modern birds around us and the most influential animals we never knew.  Let's go check out the American Museum of Natural History's best (I'm biased.) temporary exhibit, called Dinosaurs Among Us.

I had the privilege of being taken in as an explainer for this exhibit during the spring and summer of this year before I had to move out of New York.  When I first stepped in for the training walkthrough, the amount of sheer information was almost overwhelming, even for a museum.  Essentially this exhibit has a two main messages.  The first is to explain, on a broader sense, by using dinosaurs as the model, how evolution works.  The second is to bring home the fact that birds are dinosaurs, by the use of many awesome physical pieces of evidence, some of which have never been on public display before.

One of the life-sze Microraptor models hanging from the ceiling.  They have been painted glossy black-blue in accordance with the preserved melanosomes in their fossilized feathers.

When you first walk in you are greeted by life-sized life reconstructions of several of the keynote dinosaurs featured in the exhibit.  Most important is probably Citipati, due to the sheer amount of fossil material that has been found, and the fact that the American Museum of Natural History does a lot of field work in Mongolia, where this dinosaur was native to, and therefore has access to a lot of its fossils.  The largest and most dramatic model, however, is definitely Yutyrannus.  To my knowledge, a life-sized life reconstruction of this monster has never been made before this, and it looks great. Many of the life reconstructions actually feature real bird feathers, as well.

My first interaction with the Yutyrannus was a bit rocky.  We're cool now, though.

One key connection between birds and other dinosaurs is the act of nest building.  This exhibit features several spectacular fossils of nests and eggs that were laid by dinosaurs millions of years ago.  The manner in which these eggs were laid actually gives us clues as to just how closely related a species dinosaur mother was to her modern relatives.

Life-size replica of a Gigantoraptor nest on display in Dinosaurs Among Us.  Yes, you're allowed to stand in it.
One very interesting way to tell is whether or not the eggs in a dinosaur's nest were laid in pairs.  Check out this replica of a Gigantoraptor's nest above.  See how the eggs are spaced in twos?  That means that the mother of these eggs had two functioning ovaries, and was producing an egg from each of them.  This is in contrast to nests like...


This, laid by a troodontid, called Byronosaurus.  The eggs aren't arranged in pairs.  This looks more similar to a clutch of eggs laid by a modern bird.  This is because modern birds only have one functional ovary, and therefore only lay one egg at a time, resulting in this arrangement.  (Fun fact: They have two ovaries as an embryo, but lose one as they develop.  This tells us that they evolved from dinosaur ancestors with two.) We used to think this was an adaptation for lightness so they could fly...but here are some non-avian dinosaurs that didn't fly...and went extinct that way.

Telling you just how close a particular non-avian dinosaur is related to modern birds is a constant theme throughout this exhibit.  In fact, under each specimen, there is a tiny infograph, modeled after a barometer, with the needle pointing somewhere between the earliest ancestral dinosaur and modern birds.

Dino-Bird-o-meters are all over this exhibit.  In this case, it is telling us that Yutyrannus, a tyrannosauroid, is more closely related to modern birds than it is to many other kinds of dinosaurs.

After eggs and nests the exhibit looks at the actual anatomy of different dinosaurs, especially the bones.  As with single ovaries, hollow bones was another feature we used to think birds evolved specifically for flight.  Since then we have learned that this was also not the case.  Large dinosaurs, like Allosaurus, demonstrated here, and even gigantic sauropods, had hollow bones.  We now think this was a sign of having a more efficient one-way respiratory system that birds retain today.  When a bird breathes air into its lungs, it doesn't simply get exhaled out the same way it went in.  It goes into more chambers throughout the body, including ones connected to hollow cavities in the bones.  Birds today use it to help them fly better, most likely, but prehistoric dinosaurs probably used it for other reasons, like getting oxygen throughout their huge bodies more efficiently.  We have also found similar respiratory systems in modern crocodilians and even some kinds of lizards so...yea definitely not a specific flight adaptation.

This is a broken piece of an Allosaurus leg bone,displayed next to the bone of a modern bird.  The hollow inside has since been fossilized with a different mineral from the actual bone.

Having fused clavicles, or a wishbone, was another feature previously thought to be exclusive to birds...until it started popping up in the fossil record in dinosaurs like Velociraptor.  This exhibit has an awesome articulated Velociraptor specimen on display with the wishbone clearly visible.

Beautifully articulated Velociraptor specimen.  You can see the shallow v-shaped clavicle at the base of the neck.

My favorite specimen in this exhibit would be the Tyrannosaurus wishbone, however.  That's right, T. rex had a wishbone, just like that turkey you ate.  To drive the point home even harder, it is displayed in a case surrounded by the wishbones of various modern birds.

T. rex wishbone.  My favorite piece in the exhibit.

Finally the exhibit goes from internal anatomy, like bones, to external anatomy, like skin and feathers. A myriad of specimens showcasing visible preserved feathers on fossilized bodies is showcased here from the curious quill-like structures of Tianyulong...

Tianyulong cast on display, complete with bristles on the back.

To the extremely feathered, Confuciusornis, in all its plumed glory.

Confuciusornis.  Just one of many feathered specimens on display at Dinosaurs Among Us.

At the end of this exhibit, a common question we receive from guests is "So what defines a bird?" This is a great question.  Yes, birds are dinosuars...but not all dinosaurs were necessarily birds, of course.  It's like saying a Ferrari is a car, but the car I drove to New Jersey to see my family today sure as heck wasn't one!  So what they are really asking is where in the fossil record do we draw the line between birds and non-avian dinosaurs?  What combination of features can we confidently say that all birds must have to be considered a bird?


Archaeopteryx fossil.  For a long time this was the only feathered fossil known to science.  Because of that, Archaeopteryx was referred to as the "first bird" when in reality the line between "bird" and "other dinosaurs" is too blurred determine where one stops and the other begins.

The answer to this is as frustrating as it is beautiful; We don't know!  And to put it bluntly...we shouldn't really care.  Nature has nothing to do with which label we put on which organism.  They evolve to survive and the process just is what it is.  Labeling something a bird based on an anatomical milestone just can't flow with what actually happens.  The amazing side of this seemingly frustrating coin is that this means that the fossil record for non-avian dinosaurs to birds is rich with plenty of specimens to learn from for years to come.  This is in harsh contrast to as little as a few decades ago when all we had to work with as far as feathered, birdlike dinosaurs were concerned, was good old Archaeopteryx, once considered "the first bird" and now just one of many feathered, birdlike dinosaurs.

If you have an interest in paleontology, birds, or nature in general PLEASE visit this exhibit if you have not already.  The American Museum of Natural History has been a prominent part of my life since I was born.  I've seen lots of fantastic temporary exhibits come and go.  That being said, this exhibit blew me away.  I purposely didn't write about and include photos of everything in there.  In fact, I only showed you a smaller portion of what this exhibit has to offer to further encourage you to go out and see it in person for yourself.