Caseidae
| Caseidae Temporal range: Late Carboniferous - Middle Permian,
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| Fossil skeleton of Cotylorhynchus romeri | |
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| Life restoration of Cotylorhynchus | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Clade: | †Caseasauria |
| Family: | †Caseidae Williston, 1912 |
| Genera | |
Caseidae is an extinct family of synapsids ranging from the Late Carboniferous to Middle Permian. While the most primitive known caseid, Eocasea, was a small carnivore, the rest of the group were medium-large sized herbivores with barrel shaped bodies and proportionally small heads. They were one of the first groups of tetrapods to evolve herbivory. Some members of the group reached lengths exceeding four metres and weights of several hundred kilograms, making them amongst the largest terrestrial animals of the Permian period.
Characteristics
All caseids, whether modest or enormous, are characterized by small cervical vertebrae, bulky, barrel-shaped bodies and relatively massive limbs. Although ranging in size from 1–5.5 metres (3 ft 3 in – 18 ft 1 in) in body length, caseids were surprisingly conservative in their skeletal anatomy and body proportions. All were large animals with small heads and barrel-like bodies. Some, like Angelosaurus and Cotylorhynchus, which exceeded 4 meters long and were the largest of the pelycosaurs.[1]
Recent studies on caseid ribs suggest that the animals may have possibly possessed a diaphragm to assist their breathing. It was less efficient than that of their modern mammal relatives, being capable of limited costal ventilation. It likely relied on support from the animal's abdominal musculature.[1]
Skull
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.
See also
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
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