#achelousaurus

here are this week's #Paleostream drawings!

today we drew Dinocephalosaurus, Enoploura, Achelousaurus, and Arizonasaurus

In this month:

- after snapping from his viking sona, David, Frida, Hilda, and Twig must save this Achelosaurus from a gang of Troodontids

- Johanna goes for a swim on her own, encountering a curious Hynerpeton

- the Marra cheese it when the black hound and a Giganotosaurus decide to fight, leaving Frida behind

- Twig watches from a distance as a family of Buitreraptor follow the river downstream

Well, let's start this off with the thing in my profile pic. This is an older piece I done while I should have been paying attention to a class zoom call (~Feb-March 2021). The dinosaur that I intended to depict here is the enigmatic TMP 2002.76.1, more often referred to as the "Dinosaur Park Pachyrhinosaur" or "Iddesleigh Pachyrhinosaur." This fossil consists of a nearly complete skull and postcranium found at the very top of the Dinosaur Park Formation, and represents the earliest occurrence of a pachyrostran in the fossil record, roughly 500,000 years older than Achelousaurus and 1,000,000 years older than the earliest Pachyrhinosaurus proper. This specimen doesn't preserve the parietal portion of the frill and as such is difficult to resolve phylogenetically. It consistently groups in a polytomy with the previously mentioned genera, so it may belong to either of them or be a new taxon altogether. Interestingly the animal has pathological feet, with several of the phalanges of the hands and one foot showing stress fractures, resorption and destruction of distal elements, likely losing some of its toes.

For my part, I kind of dropped the ball on this one. I restored it as a kind of generic Pachyrhinosaurus. I like my work well enough on its own, but it doesn't really represent the fossil itself all too well. Mainly the area between the boss and beak, which I restored with two lateral scales more like in Pachyrhinosaurus canadensis, and the area between the nasal and supraorbital bosses which I made way too small. Additionally, though the frill is not known in TMP 2002.76.1 it probably wasn't the Pachyrhinosaurus frill I gave it.

I may revisit this in the future and give this fascinating fossil its proper due

The original description:

Ryan, M. J., et. al. (2008) A New Pachyrhinosaurus-Like Ceratopsid from the Upper dinosaur Park Formation (Late Campanian) of Southern Alberta, Canada. In M. J. Ryan, B. J. Chinnery-Allgeier, and D. A. Eberth, eds., New Perspective on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium, pg. 141-155. Bloomington: Indiana University Press

The pathologies of the toes (pg. 372)

Flocking Together

Dinocephalosaurus/Enoploura

Achelousaurus

achelousaurus horneri - centrosaurine - late cretaceous discovered by the lovely jack horner, this intimidating ceratopsid lady has Quite the eyebrows. she was part of a study relating to the debate of thermoregulation in dinosaurs- whether they could generate heat or not, like current avian dinosaurs and mammals. by analyzing oxygen isotopes in the fossils of dinosaurs found in the two medicine formation, paleontologists could pinpoint seasonal variations in body temperature! they found the variations pointed to achelousaurus and other dinosaurs in the formation being homeothermic endotherms- the same as our avian dinosaurs today!

higher resolution version and a link to the paper under the cut!