Tibia: Edmontosaurus regalis is the only known hadrosaur from the Horsetheif Member

Dromaeosaur tooth: both velociraptorinae and dromaeosaurinae are known in the formation, only the former has described at the species level (Atrociraptor marshalli). This tooth however appears to be a dromaeosaurine tooth.

Tyrannosaur tooth: Albertosaurus sarcophagus is the only known tyrannosaur from the formation. This is one of the first maxillary teeth as the anterior serrations curve strongly to the lateral-posterior. The photo doesn’t show it though as the posterior serrations are on the underside.

Are we looking at the Bearpaw Formation here?

This is all in the Horsetheif member of the Horseshoe Canyon Formation 

Dunkleosteus sp.

Artwork by Julio Lacerda / @paleoart

This orca-sized fish had strong jaws with sharp bony plates forming a beak-like structure used to break the armor of its prey. It lived around 380-360 million years ago when armored fishes ruled the oceans.

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252MYA creates custom-made artwork for private collections and editorial, scientific, or educational project.

The first casting of our Daspletosaurus from the BOB Block. This particular cast found its home at the Australian Museum as part of its Tyrannosaurs - Meet the Family exhibit in 2013.

Why do dino nerds always sound so sad that the dinosaurs went extinct?  It’s the reason you have a job!  It permitted your existence!

All I want is to be able to ride a Pachycephalosaurus to campus. I was ripped apart from that dream. That is why I am sad.

Various complete Edmontosaurus skulls.

American Museum of Natural History, Part 33: The Dinosaur Halls Part 3: MAAAY CHILDREN

I love Hadrosaurs. They’re my favorite group of dinosaurs (followed closely by a tie between penguins and dromaeosaurs, with corvids taking third place). I love them. My precious children. I took a lot of pictures even though the glass-glare thing was an issue. 

We’ve got Saurolophus, Saurolophus, Hypacrosaurus, Hypacrosaurus, Hypacrosaurus, Edmontosaurus mummy!, Edmontosaurus, Kritosaurus, and Lambeosaurus

Look at the bab Hypacrosaurus 😍😍😍😍😍 so smol 

American Museum of Natural History, Part 24: Awkward Outdated Grouping

So back in the day, we thought that turtles - which have secondarily derived “anapsid” (ie, no temporal fenestrae) skulls, evolved from what we now know to be Parareptiles - one of the two first divisions of Sauropsida. So:

Basically, some early tetrapods evolved the amniotic egg so they could reproduce on land instead of the water. Hooray!

This group then divided into two: Synapsids, which are all amniotes more closely related to modern mammals than to modern birds, and Sauropsids, which are the reverse. Synapsids would later evolve into mammals and all modern synapsids are mammals. 

Sauropsids had two early branches: Parareptiles, which were “Anapsids,” and Eureptiles, which were also Anapsids but would eventually evolve into Diapsids - having two temporal fenestrae (synapsids have one; this is grossly oversimplified). 

So, because turtles were anapsids, we thought they evolved from Parareptiles. 

However, genetic evidence has revealed that they are actually more closely related to modern Archosaurs (birds and crocodilians) than they are to lizards and snakes (lepidosaurs) which, along with other evidence, implies that they are actually diapsids that lost their temporal fenestrae, and not parareptiles at all 

Anyway tl;dr the turtles were grouped with parareptiles because of outdated cladistics. So here are some good turts and some good weird early reptiles. 

What are turtles!??

I just wrote a final for one of my paleo courses (like I handed it in about t minutes a go) and we had to know all the groups they've been linked to and why.

Stegoceras validum, S. novomexicanum

S. novomexicanum by Jack Wood on @thewoodparable

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Name: Stegoceras validum, S. novomexicanum

Name Meaning: Horn Roof

First Described: 1902

Described By: Lambe

Classification: Dinosauria, Ornithischia, Genasauria, Neornithischia, Cerapoda, Marginocephalia, Pachycephalosauria, Pachycephalosauridae

Stegoceras is a very well known genus of small Pachycephalosaur that is based on many specimens and even has two species assigned to it, which mostly differ in terms of size. It was actually one of the first known Pachycephalosaurs and it was only known from skull domes, which lead to a lot of questions about this group before more complete remains were found two decades later. S. validum is about 2 to 2.5 meters long and one meter tall, about the size of a goat; S. novomexicanum appears to have been smaller and more gracile, about half the size; but it’s possible that the known specimens are actually just juveniles. Though many remains are known, the spinal column is not; it did have ossified tendons on its tail that would have formed parallel row which would have stiffened it, potentially for balance. It had a roughly triangular head with a very thick elevated dome, and it had a very heavily sculpted area around its nose. It also had differentiated teeth, which probably were used for differential foraging in its complex environment. S. validum was found in the Judith River Group, Belly River Group, Dinosaur Park Formation, Dinosaur Provincial Park, and the Oldman Formations of Canada and the United states, and it caused much confusion for paleontologists due to the lack of comparable material. Meanwhile, S. novomexicanum was found in the Kirtland Formation in New Mexico. Both lived in the Campanian age of the Late Cretaceous, between 77.5 and 74 million years ago. 

S. validum by José Carlos Cortés on @ryuukibart

Many individuals of many physiological ages are known which show the ontogenetic sequence of Stegoceras’ skull growth, progressing from the flat skull stage to the dome stage, which has lead to the understanding of many more ontogenetic sequences in Chunkies. Adults - with the dome heads - have also been found to have lesions due to infections after trauma in the domes, which have not been found in the young; the injuries were also very common, indicating probable dome-butting between adults, potentially as intraspecific competition for mates or social position. It had a very keen sense of smell and would have been a very strong, small animal, which was necessary in its swampy and floodplain like environments. It would have lived alongside many different dinosaurs in the Judith River Group, Dinosaur Park Formation, Oldman Formation, and Kirtland Formations, such as Centrosaurus, Styracosaurus, Chasmosaurus, Prosaurolophus, Lambeosaurus, Gryposaurus, Corythosaurus, Parasaurolophus, Edmontonia, Euoplocephalus, Gorgosaurus, Daspletosaurus, Brachylophosaurus, Coronosaurus, Albertaceratops, Saurornitholestes, and many others. 

Shout out goes to @purdyssciencecorner!

And 

Limnofregata azygosternon!

The Eocene Dinosaurs from the Field Museum! (Field Museum Photos part 3)

Stegoceras validum

My faves!!!

Dr. Holly Woodward talks paleohistology next! Is #Nanotyrannus actually juvenile T.rex? (Spoiler alert: YES.) #Dinofest #cle (at Cleveland Museum of Natural History)

So much to do and precious little time

I’ve heard it said that study of our prehistoric past teaches us that “the only constant in life on Earth is change.”  This may be true, but I favor a different epitome of palaeontology: nothing has ever lived that will not die.  What a tragedy this is.  Putting the necessities of survival aside, there is so much beauty in every facet of the organismal world it is a shame to see any of it end or, far worse, not live myself to see its subsequent iterations.  Such complexity too, seen in the compartmental industry of the prokaryote or the delicate extravagance of many angiosperms.  These die in numbers I can’t even fathom.  I could enthuse breathlessly about the Porifera: towers of interworked spines with ever branching channels servicing a common opening; thousands of flagella beating ceaselessly with the current.  If you smash a sponge, running it through a grate until you’re left with nothing but a pile of spicules and a milieu of cells, it will rebuild, given enough time.  Not only that, but it remembers what it is and what it once was: mix two sponges together, and the cells of each sponge will shun the other, rebuilding only with its own kin.  These too all die.  It’s easy (and good) to be inure to all this death.  To me, it’s a question of scale.  I suppose I’m just taking a wider version of the particularly Japanese fetish of the cherry blossom.  All life is ephemeral – the loss of thousands of cherry blossoms frames the loss of thousands of human lives in wartime.  This, in turn, frames a different loss.  Some day our beautiful, complex universe will die too.  It sprung up ex nihilo and to nothing it shall return again.

So having resolved that I am not immortal and that complexity of being or thought is no safeguard against death, I am faced with a curve of cumulative probability.  I could be dead in a gutter tomorrow; but probably not. Not the day after tomorrow either (no matter what Roland Emmerich might say).  But each day stacks upon the next and, by some point in the next 130 years, p = 1.  I’ve a lot to do before that inevitability.  I dream of knowing things about our world, through careful and diligent study, that no one has ever known before.  I want to name new taxa and restore known taxa to their rightful place in our systems of thought.  I want to lighten the burden of this world to others; I want to show people what I know about the natural world and help them grasp the wonder of life in their own ways.  I want to love and find companionship.  I want to build an empire.  There’s so much to do, and precious little time.

But I digress.  I must go to bed.  I have a busy day tomorrow.  I’ve got to sleep and eat and drink.  I’ll have to walk to the lab and make some small talk along the way.  I’ll write emails which change nothing and check my Facebook. Then I’ll pick up groceries.  Oh, and tomorrow’s Thursday.  There’ll be football on TV, and, come to think of it, I really feel like playing some Battlefield too. 

Yes, there’s so much to do, and precious little time. 

It’s time for a #tbt look into the archives. Legendary fossil hunter Roy Chapman Andrews first ventured to the region in the 1920s, leading a series of expeditions that would go down in the annals of paleontology and pop culture alike. Alongside colleagues like Henry Fairfield Osborn and Walter Granger, he not only discovered new species of fossil mammals and dinosaurs, but also unearthed the first clutch of dinosaur eggs in 1923.