Caseasauria
Encyclopedia
The Caseasauria are one of the two main clade
s of early synapsids, the other being the Eupelycosauria
. They are currently known only from the Permian
, and include two superficially different families, the small insectivorous or carnivorous Eothyrididae
, and the large herbivorous Caseidae
These two groups share a number of specialised features associated with the morphology of the snout and external naris and it is likely that the latter evolved from the former.
The ancestors of Caseasaurs can be traced back from an insect eating or an omnivorous reptile
-like synapsid
from the Pennsylvanian
time of the Carboniferous
, that resembles Archaeothyris
. The Caseasaurs were abundant and successful during the later part of the early Permian
epoch. But by the middle Permian, the Caseasaurs became less abundant because of the evolving, more successful therapsids and by late Permian, they were facing extinction. The last Caseasaurs became extinct in the Permian–Triassic extinction event; no species of Caseasaurs made it to the Triassic
Period.
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...
s of early synapsids, the other being the Eupelycosauria
Eupelycosauria
The Eupelycosauria originally referred to a suborder of 'pelycosaurs' , but has been redefined to designate a clade of synapsids that includes most pelycosaurs, as well as all therapsids and mammals...
. They are currently known only from the 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...
, and include two superficially different families, the small insectivorous or carnivorous Eothyrididae
Eothyrididae
The Eothyrididae were a small group of very primitive, insectivorous synapsids. Only two genera are known, Eothyris and Oedaleops, both from the early Permian of North America...
, and the large herbivorous 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...
These two groups share a number of specialised features associated with the morphology of the snout and external naris and it is likely that the latter evolved from the former.
The ancestors of Caseasaurs can be traced back from an insect eating or an omnivorous reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
-like synapsid
Synapsid
Synapsids are a group of animals that includes mammals and everything more closely related to mammals than to other living amniotes. They are easily separated from other amniotes by having an opening low in the skull roof behind each eye, leaving a bony arch beneath each, accounting for their name...
from the Pennsylvanian
Pennsylvanian
The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...
time of the Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
, that resembles Archaeothyris
Archaeothyris
Archaeothyris was a very early mammal-like reptile, which lived in the late Carboniferous period. Dated to 306 million years ago, it is the oldest undisputed synapsid known....
. The Caseasaurs were abundant and successful 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...
epoch. But by the middle Permian, the Caseasaurs became less abundant because of the evolving, more successful therapsids and by late Permian, they were facing extinction. The last Caseasaurs became extinct in the Permian–Triassic extinction event; no species of Caseasaurs made it to the Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
Period.