#acrotholus

(I have yet to give them actual names aside of their nicknames) Pronks is sure he can fist fight an Acrotholus! Lorn reminds him that that's how he lost his leg the last time...

After a pretty long while here’s a selection of my pieces for the A Dinosaur A Day blog! Soon enough I’ll be uploading another one full of horned faces, for now it’s just Protoceratops hehe.  Showcasing Brachylophosaurus, Edmontosaurus, Acrotholus, Stegoceras, "Microcephale", a Pachycephalosaurus juvenile (formerly Dracorex), Protoceratops, the non-dinosaurian Scleromochlus, Savannasaurus, and Tatisaurus

The high dome, Acrotholus audeti (2013)

Phylum : Chordata Class : Reptilia Order : Ornithischia Family : Pachycephalosauridae Genus : Acrotholus Species : A. audeti

Late Cretaceous (84 - 83,5 Ma)

180 cm long and 40 kg (size)

Milk river formation, Canada (map)

Sometime during the middle Cretaceous period, about 100 million years ago, a population of ornithopods--small, bipedal, plant-eating dinosaurs--evolved into the first pachycephalosaurs. The recently announced Acrotholus is the earliest bone-headed dinosaur to be discovered in North America, predating the previous record-holder by five million years, and it's one of the earliest pachycephalosaurs yet identified-- possibly only recently evolved from its ornithopod ancestors.

Aside from its place at the base of the pachycephalosaur family tree, Acrotholus is also important because it points to a previously unappreciated diversity among small, herbivorous, Cretaceous dinosaurs.

By José Carlos Cortés on @ryuukibart​

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Name: Acrotholus audeti

Name Meaning: Highest Dome

First Described: 2013

Described By: Evans et al. 

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

Acrotholus is our first definitive Pachycephalosaur, a group of strange and rare bipedal Ornithischians with famed domed heads. In fact, this chunkie is one of the oldest known Pachycephalosaurs from North America, dating back to about 84 to 83.5 million years ago, in the Santonian age of the Late Cretaceous. It was found in the Milk River Formation in Alberta, Canada. Pachycephalosaurs are characterized by having a fairly sparse fossil record, seemingly appearing out of nowhere and mostly formed as they were (with domed heads and bipedal stature). Acrotholus sheds some light on this mystery, though it was a fairly derived Pachycephalosaur for being so early in the fossil record. It was fairly small like most Pachycephalosaurs, and in fact this small size may be why Pachycephalosaurs are so poorly known - small animals, in general, are underrepresented compared to their diversity in the fossil record. It probably would have, thus, been less than 40 kg in weight. It is only known from limited remains, mostly of the dome itself, so it remains a poorly known genus. 

Source: 

Evans, D. C., R. K. Schott, D. W. Larson, C. M. Brown, M. J. Ryan. 2013. The oldest North American pachycephalosaurid and the hidden diversity of small-bodied ornithischian dinosaurs. Nature Communications 4: 1828.