Angelosaurus
Encyclopedia
Angelosaurus dolani was a pelycosaur
(an extinct clade
) of reptile. It is known from a partial skull from the Middle San Angelo Formation, Knox County, Texas, USA. It dates from the Kungurian
(Early Permian
). It was from three to three and a half metres long and weighed about 300 kilograms. It belongs to the family Caseidae
. Like its contemporary, another caseid, Cotylorhynchus
, it was large, heavily built, and herbivorous. It also shared its environment with the caseids Caseoides
and Caseopsis
. It may have been preyed upon by the large sphenacodon
t pelycosaur Dimetrodon
.
Like all caseids, Angelosaurus was an evolutionarily conservative reptile which would appear to have been one of the dominant herbivores of the time, occupying a similar ecological role to cows. Caseid skulls are distinguished from other pelycosaurs by large temporal openings, large nasal
and pineal openings and an upper jaw that distinctively overhangs the teeth of the lower jaw.The skull is pitted. The teeth are uniform. The body was probably barrel-shaped, like other caseids, with massive limbs and small cervical vertebrae. And unlike the more well-known pelycosaurs such as Dimetrodon and Edaphosaurus
, caseids do not have the exaggerated elongation of the vertebrae that form a sail.
Two other species of Angelosaurus have been described so far: Angelosaurus greeni Olson 1962, and Angelosaurus romeri Olson and Barghusen, 1962.
Pelycosaur
The pelycosaurs are an informal grouping composed of basal or primitive Late Paleozoic synapsid amniotes. Some species were quite large and could grow up to 3 meters or more, although most species were much smaller...
(an extinct clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
) of reptile. It is known from a partial skull from the Middle San Angelo Formation, Knox County, Texas, USA. It dates from the Kungurian
Kungurian
In the geologic timescale, the Kungurian is an age or stage of the Permian. It is the latest or upper of four subdivisions of the Cisuralian epoch or series. The Kungurian lasted between 275.6 ± 0.7 and 270.6 ± 0.7 million years ago...
(Early Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
). It was from three to three and a half metres long and weighed about 300 kilograms. It belongs to the family Caseidae
Caseidae
The Caseidae were a widespread group of very primitive herbivorous synapsids, which appeared during the later early Permian and persisted until the late middle Permian. Although ranging in size from 1 to 5½ meters in body length, caseids were surprisingly conservative in their skeletal anatomy and...
. Like its contemporary, another caseid, Cotylorhynchus
Cotylorhynchus
Cotylorhynchus was a very large mammal-like reptile that lived in the southern part of what is now North America during the Early Permian period and persisted until the late-Mid Permian...
, it was large, heavily built, and herbivorous. It also shared its environment with the caseids Caseoides
Caseoides
Caseoides was a large pelycosaur synapsid that lived in the Kungurian Age . It was about 3 meters long, and like many other caseids, it was herbivorous. It weighed between 150 kg to 200 kg. Its fossils were found on Texas. Caseoides was very similar to Casea, but was slightly larger in size...
and Caseopsis
Caseopsis
Caseopsis was a large pelycosaur that was about 3 meters long. Caseopsis lived in the late Early Permian epoch , before the pelycosaurs were replaced by the more advanced therapsids . It was a lightly built, agile creature. It may have been possible for this species to outpace and escape large...
. It may have been preyed upon by the large sphenacodon
Sphenacodon
Sphenacodon was a pelycosaur that was about in length. Sphenacodon belongs to the family Sphenacodontidae, a lineage that was related to the therapsids...
t pelycosaur Dimetrodon
Dimetrodon
Dimetrodon was a predatory synapsid genus that flourished during the Permian period, living between 280–265 million years ago ....
.
Like all caseids, Angelosaurus was an evolutionarily conservative reptile which would appear to have been one of the dominant herbivores of the time, occupying a similar ecological role to cows. Caseid skulls are distinguished from other pelycosaurs by large temporal openings, large nasal
Nose
Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for respiration in conjunction with the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passes through the pharynx, shared with the...
and pineal openings and an upper jaw that distinctively overhangs the teeth of the lower jaw.The skull is pitted. The teeth are uniform. The body was probably barrel-shaped, like other caseids, with massive limbs and small cervical vertebrae. And unlike the more well-known pelycosaurs such as Dimetrodon and Edaphosaurus
Edaphosaurus
Edaphosaurus is a genus of prehistoric synapsid which lived around 303 to 265 million years ago, during the late Carboniferous to early Permian periods. The name Edaphosaurus means "ground lizard" and is derived from the Greek edaphos/εδαφος and σαυρος/sauros...
, caseids do not have the exaggerated elongation of the vertebrae that form a sail.
Two other species of Angelosaurus have been described so far: Angelosaurus greeni Olson 1962, and Angelosaurus romeri Olson and Barghusen, 1962.