''Oedaleops'' is an extinct genus of caseasaur

synapsid Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...

s 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 The Cutler Formation or Cutler Group is a rock unit that is exposed across the U.S. states of Arizona, northwest New Mexico, southeast Utah and southwest Colorado. It was laid down in the Early Permian during the Wolfcampian epoch. Descri ...

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

, 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. in 1965 on the basis of a mostly complete skull (specimen

UCMP The University of California Museum of Paleontology (UCMP) is a paleontology museum located on the campus of the University of California, Berkeley. The museum is within the Valley Life Sciences Building (VLSB), designed by George W. Kelham and ...

35758, the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

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 ''Aerosaurus'' (meaning "copper lizard") is an extinct genus within Varanopidae, a family of non-mammalian synapsids. It lived between 252-299 million years ago during the Early Permian in North America. The name comes from Latin ''aes'' (''aeris ...

''. 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 Pectoral may refer to: * The chest region and anything relating to it. * Pectoral cross, a cross worn on the chest * a decorative, usually jeweled version of a gorget * Pectoral (Ancient Egypt), a type of jewelry worn in ancient Egypt * Pectorali ...

and limb bones, and disarticulated 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 In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

or eye sockets and numerous teeth, the most of any caseasaur. It differs from its closest relative ''Eothyris'' in having a

frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, pa ...

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 An infratemporal fenestra, also called the lateral temporal fenestra or simply temporal fenestra, is an opening in the skull behind the orbit in some animals. It is ventrally bordered by a zygomatic arch. An opening in front of the eye sockets ...

. ''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 vertebrae 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 In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

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, which also includes a family of mostly herbivorous Early Permian synapsids called Caseidae. The majority of analyses place Caseasauria as the basal-most clade within Synapsida. With caseids and eothyridids are equally closely related to the

last common ancestor In biology and genetic genealogy, the most recent common ancestor (MRCA), also known as the last common ancestor (LCA) or concestor, of a set of organisms is the most recent individual from which all the organisms of the set are descended. The ...

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 A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...

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