Caseidae
Encyclopedia
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 (3–18 feet) 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 pelycosaur
s, seemed to have played the same ecological role during the later part of the early Permian
that the pareiasaur
s and herbivorous dinocephalia
ns 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.
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...
and persisted until the late middle Permian. Although ranging in size from 1 to 5½ meters (3–18 feet) 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
Angelosaurus
Angelosaurus dolani was a pelycosaur of reptile. It is known from a partial skull from the Middle San Angelo Formation, Knox County, Texas, USA. It dates from the Kungurian . It was from three to three and a half metres long and weighed about 300 kilograms...
and 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...
, which exceeded 4 meters long and were the largest of the pelycosaur
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...
s, seemed to have played the same ecological role during the later part of the 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...
that the pareiasaur
Pareiasaur
The Pareiasaurs - Family Pareiasauridae - are a clade of medium-sized to large herbivorous anapsid reptiles that flourished during the Permian period....
s and herbivorous dinocephalia
Dinocephalia
Dinocephalia are a clade of large early therapsids that flourished during the Middle Permian, but became extinct leaving no descendants.-Description:...
ns did during the Middle and Late 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...
.
The caseid skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
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
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...
, 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
Cervical vertebrae
In vertebrates, cervical vertebrae are those vertebrae immediately inferior to the skull.Thoracic vertebrae in all mammalian species are defined as those vertebrae that also carry a pair of ribs, and lie caudal to the cervical vertebrae. Further caudally follow the lumbar vertebrae, which also...
, bulky, barrel-shaped bodies and relatively massive limbs.