Tag Archives: diapsid

Know Your Bones: February 2014

Last month, I tried to throw a hard ball your way, because the month before was so easy. However, Isotelus easily identified this critter within a day of the blog being posted.


I love me some Aetosaurs! My guess: Originally Desmatosuchus haplocerus, now thought to be D. smalli.


Isotelus is correct, this specimen is an Aetosaur called Desmatosuchus. Whether this is D. haplocerus or D. smalli is unknown to me (way to make me look bad Isotelus).


(Taken at the New Mexico Museum of Natural History and Science)

Desmatosuchus lived 201 – 252 million years ago, during the late Triassic. As one can see from the skeleton, Desmatosuchus, as well as all Aetosaurs were armored creatures. The armored plates found on the back were most likely used as defense against larger predators that existed during the late Triassic. Something that might be less obvious is that Desmatosuchus, like all Aetosaurs, were most likely vegetarians. Another thing that is also not immediately obvious is that the closest living relative to Aetosaurs are crocodilians.


(Taken at the New Mexico Museum of Natural History and Science)

This means that not only is Desmatosuchus a member of the diapsid clade, but also a member of the archosaur clade. This clade includes everything you see in the image above. Aetosaurs make up an early example of armored archosaurs, something archosaurs will do again in the centuries to come.


Moving on to this months challenge:


(Taken at the New Mexico Museum of Natural History and Science)

Good luck to everyone. I also want to say that I like the fact that people are posting their answers as hidden.

Know Your Bones: January 2014

Last month’s challenge was very easy. It was so easy that duclicsic posted a correct answer within minutes of the blog going up. However, later in the month Aught3 posted an even more correct answer:


Dimetrodon limbatus

Reason: Google-fu


This is a specimen of Dimetrodon and Aught3 is even more correct in that it is specifically Dimetrodon limbatus.


 (Taken at the New Mexico Museum of Natural History and Science)

Dimetrodons inhabited the earth 295 – 272 million years ago, during the Permian. Dimetrodons were most likely the top predator on earth during that time. The most prominent feature of Dimetrodon is the sail on its back. The sail was most likely used as a heat regulator, but some scientists have suggested that it might be an example of sexual selection, similar to the Peacock’s tail. Either way, the sail on its back and four-legged posture makes Dimetrodon one of the easiest prehistoric critters to identify.


There is confusion about Dimetrodon, in that several people believe that it was a dinosaur, I think this is because Dimetrodons are always found in Prehistoric Play Sets and most people believe dinosaurs were just big lizards. Dimetrodon does resemble a large lizard with a sail on its back. However, there are three main reasons Dimetrodon was not a dinosaur; the first most obvious one is that it is much older than any dinosaur. The second is the sprawling, lizard-like stance of its legs. Dinosaurs’ legs, unlike lizards, are directly under their bodies and not protruding from the side of the body like modern lizards. The third is that Dimetrodon is actually more closely related to modern mammals than it is to reptiles such as dinosaurs.


Dimetrodon belongs to the synapsid clade along with all mammals. This means that behind the eye, there is only one hole for muscle attachments. Dinosaurs belong to the diapsid clade, meaning they have two holes behind the eye for muscle attachments.


Moving on to this months challenge:


 (Taken at the Dinosaur Museum and Natural Science Laboratory)

Good luck and happy 2014.