Caseidae

Taxobox
name = Caseidae
fossil_range = Early-Mid Permian


image_width = 250px
image_caption = "Cotylorhynchus"
regnum = Animalia
phylum = Chordata
subphylum = Vertebrata
classis = Synapsida
ordo = Pelycosauria
subordo = Caseasauria
familia = Caseidae
familia_authority = Williston, 1912
subdivision_ranks = Genera
subdivision = "Angelosaurus" "Casea" "Caseopsis" "Caseoides" "Cotylorhynchus" "Ennatosaurus" "Eunotosaurus" "Knoxosaurus" "Oromycter"The Caseidae were a widespread group of very primitive herbivorous synapsids, they appeared during the later early Permian and persisted until the late middle Permian. Although ranging in size from 1 to 5 1/2 meters (18 feet) in body length, caseids are surprisingly conservative in their skeletal anatomy and body proportions. All were large-sized animals with small heads and barrel-like bodies. Some like "Angelosaurus" and "Cotylorhynchus", which exceeded 4 meters in length and were the largest of the pelycosaurs, and seemed to have played the same ecological role during the later part of the early Permian that the pareiasaurs, herbivorous dinocephalians did during the Middle and Late Permian.

The caseid skull is distinctive in the presence of large temporal openings, enormous external nares (probably to house some kind of sensory or moisture-conserving organ), and large pineal opening, and a snout or upper jaw that dramatically overhangs the tooth row to form a forward projecting rostrum. The external surface of the skull is sculpted with rounded deep pits and sometimes crevice-like depressions. The marginal teeth are quite similar to the teeth of pareiasaurs.

In contrast to most other synapsids, except "Edaphosaurus", and as befits the herbivorous lifestyle, the teeth are remarkably uniform. There is a general reduction in the number of marginal teeth and cheek teeth. All caseids, whether modest or enormous, are characterized by small cervical vertebrae, bulky, barrel-shaped bodies and relatively massive limbs.

ee also

* Eothyrididae
* Evolution of mammals

References

* Romer, AS & Price L.I (1940), Review of the Pelycosauria. "Geol. Soc. Amer. Spec. Papers" 28: 1-538.
* Reisz, R. R., 1986, "Handbuch der Paläoherpetologie – Encyclopedia of Paleoherpetology, Part 17A Pelycosauria" Verlag Dr. Friedrich Pfeil, ISBN 3-89937-032-5

External links

* [http://tolweb.org/notes/?note_id=466 Tree of Life]
* [http://www.palaeos.com/Vertebrates/Units/Unit390/100.html Palaeos Vertebrates 390.100 Synapsida]