''Oedaleops'' is an extinct genus of

caseasaur Caseasauria is one of the two main clades of early synapsids, the other being the Eupelycosauria. Caseasaurs are currently known only from the Late Carboniferous and the Permian, and include two superficially different families, the small insect ...

synapsids from the

Early Permian 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), 01'' (Richard Müller album), 2001 * 01 (Son of Dave album), ''01'' (Son of Dave album), 2000 * 01 (Urban ...

of the southwestern United States. Fossils have been found in the Cutler Formation in New Mexico, which dates back to the Wolfcampian stage of the Early Permian. All remains belong to the single known species ''Oedaleops campi''. ''Oedaleops'' was closely related to ''

Eothyris ''Eothyris'' is a genus of extinct synapsid in the family Eothyrididae from the early Permian. It was a carnivorous insectivorous animal, closely related to '' Oedaleops''. Only the skull of ''Eothyris'', first described in 1937, is known. It ...

'', and both are part of the family

Eothyrididae Eothyrididae is an extinct family of very primitive, insectivorous synapsids. Only three genera are known, ''Eothyris'', '' Vaughnictis'' and '' Oedaleops'', all from the early Permian of North America. Their main distinguishing feature is the l ...

. Like ''Eothyris'', it was probably an insectivore.

Discovery

''Oedaleops'' was first described by paleontologist

Wann Langston Jr. Wann Langston Jr. (1921 – April 7, 2013) was an American paleontologist and professor at the University of Texas at Austin. Langston worked on a number of different reptiles and amphibians in his long career, beginning with the 1950 description ...

in 1965 on the basis of a mostly complete skull (specimen UCMP 35758, the holotype of ''Oedaleops'') and a few isolated skull and postcranial fragments. The UCMP 35758 skull has been the sole specimen of ''Oedaleops'' used in most analyses of its evolutionary relationships. The more fragmentary specimens have been assigned to ''Oedaleops'' with caution because they are hard to distinguish from the bones of other Cutler Formation synapsids such as '' Aerosaurus''. Additional specimens of ''Oedaleops'' were described in 2013, including many isolated

dentaries In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

(lower jaw bones), pectoral and limb bones, and

disarticulated In medical terminology, disarticulation is the separation of two bones at their joint, either traumatically by way of injury or by a surgeon during arthroplasty or amputation. See also * Joint dislocation * Acrotomophilia * Apotemnophilia * Amputa ...

vertebrae representing at least three new individuals.

Description

''Oedaleops'' has a wide and low skull with a convex margin when viewed from the side. It has large orbits or eye sockets and numerous teeth, the most of any caseasaur. It differs from its closest relative ''Eothyris'' in having a frontal bone that forms a greater portion of the upper margin of the orbit. Another distinguishing feature of ''Oedaleops'' is the thinness of the postorbital bar, a strut of bone separating the back of the orbit from a hole in the back of the skull called the temporal fenestra. ''Oedaleops'' lacks the enlarged

caniniform In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, or (in the context of the upper jaw) fangs, eye teeth, vampire teeth, or vampire fangs, are the relatively long, pointed teeth. They can appear more flattened howeve ...

teeth and blunt snout of ''Eothyris''. Because no tail bones are known, the total body length of ''Oedaleops'' is uncertain. The length of the dorsal vertebral column (the length of vertebrae making up the back) can be estimated at around from the lengths of individual

dorsal vertebra In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...

e in ''Oedaleops'' and the number of dorsal vertebrae present in related synapsids. Adding the length of the skull gives a snout-vent length (the length of the body from the tip of the skull to hips) of . Like other early synapsids, ''Oedaleops'' probably had sprawling limbs and a body set low to the ground. The front of the body may have been slightly elevated above the level of the hips.

Relationships

Since its naming in 1965, ''Oedaleops'' has been interpreted as a close relative of ''Eothyris'' from the Early Permian of Texas. Langston placed both in the family

. Since 1980, most phylogenetic analyses place eothyridids in a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

or evolutionary grouping called

Caseasauria Caseasauria is one of the two main clades of early synapsids, the other being the Eupelycosauria. Caseasaurs are currently known only from the Late Carboniferous and the Permian, and include two superficially different families, the small inse ...

, which also includes a family of mostly herbivorous Early Permian synapsids called

Caseidae Caseidae are an extinct family of basal synapsids that lived from the Late Carboniferous to Middle Permian between about 300 and 265 million years ago. Fossils of these animals come from the south-central part of the United States (Texas, Oklaho ...

. The majority of analyses place Caseasauria as the

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

-most clade within Synapsida. With caseids and eothyridids are equally closely related to the last common ancestor of synapsids, the body plan of ''Oedaleops'' and other eothyridids (characterized by large heads and relatively narrow bodies) more closely approximates what is predicted for the synapsid common ancestor than does the body plan of caseids (characterized by extremely small heads and barrel-shaped bodies). Therefore, ''Oedaleops'' is one of the most important taxa in phylogenetic analyses and the features of its skeleton have an important bearing on the relationships of other synapsids. Below is a cladogram from the phylogenetic analysis of Sumida ''et al.'' (2013) that shows many of the same relationships as those found in previous analyses, except for having ''Eothyris'' being more closely related to caseids than to ''Oedaleops'' (making Eothyrididae

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

References

* Langston, W. 1965. ''Oedaleops campi'' (Reptilia: Pelycosauria), a new genus and species from the Lower Permian of New Mexico, and the family Eothyrididae. ''Bull. Texas Mem. Mus.'' 9: 1–47.

External links

www.palaeos.com
(picture of a skullcast) {{Taxonbar, from=Q3282065 Caseasaurs Prehistoric synapsid genera Cisuralian synapsids of North America Fossil taxa described in 1965 Cisuralian genus first appearances Cisuralian genus extinctions