Eureptilia ("true reptiles") is one of the two major subgroups of the clade

Sauropsida Sauropsida ("lizard faces") is a clade of amniotes, broadly equivalent to the class Reptilia. Sauropsida is the sister taxon to Synapsida, the other clade of amniotes which includes mammals as its only modern representatives. Although early s ...

, the other one being

Parareptilia Parareptilia ("at the side of reptiles") is a subclass or clade of basal sauropsids ( reptiles), typically considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds). Parareptiles first arose near ...

. Eureptilia includes Diapsida (the clade containing all modern reptiles and

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s), as well as a number of primitive

Permo ''Permo'' is the debut studio album by Scottish indie rock Indie rock is a Music subgenre, subgenre of rock music that originated in the United States, United Kingdom and New Zealand from the 1970s to the 1980s. Originally used to describe i ...

- Carboniferous forms previously classified under Anapsida, in the old (no longer recognised) order " Cotylosauria". Eureptilia is characterized by the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, t ...

having greatly reduced supraoccipital, tabular, and

supratemporal The supratemporal bone is a paired cranial bone present in many tetrapods and tetrapodomorph fish. It is part of the temporal region (the portion of the skull roof behind the eyes), usually lying medial (inwards) relative to the squamosal and late ...

bones that are no longer in contact with the

postorbital The ''postorbital'' is one of the bones in vertebrate skulls which forms a portion of the dermal skull roof and, sometimes, a ring about the orbit. Generally, it is located behind the postfrontal and posteriorly to the orbital fenestra. In some v ...

. Aside from Diapsida, the group notably contains

Captorhinidae Captorhinidae (also known as cotylosaurs) is an extinct family of tetrapods, traditionally considered primitive reptiles, known from the late Carboniferous to the Late Permian. They had a cosmopolitan distribution across Pangea. Description ...

, a diverse and long lived (Late Carboniferous-Late Permian) clade of initially small carnivores that later evolved into large herbivores. Other primitive eureptiles such as ''

Hylonomus ''Hylonomus'' (; ''hylo-'' "forest" + ''nomos'' "dweller") is an extinct genus of reptile that lived 312 million years ago during the Late Carboniferous period. It is the earliest unquestionable reptile (''Westlothiana'' is older, but in fact i ...

'' and " protorothyrids" were all small, superficially lizard-like forms, that were probably

insectivorous A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores were ...

. One primitive eureptile, the Late Carboniferous "protorothyrid" '' Anthracodromeus,'' is the oldest known

climbing Climbing is the activity of using one's hands, feet, or any other part of the body to ascend a steep topographical object that can range from the world's tallest mountains (e.g. the eight thousanders), to small boulders. Climbing is done ...

tetrapod. Diapsids were the only eureptilian clade to continue beyond the end of the Permian.

Classification

Eureptilia was defined as a stem-based clade, specifically, the most inclusive clade containing '' Captorhinus aguti'' and '' Petrolacosaurus kansensis'' but not '' Procolophon trigoniceps'', by Tsuji and Müller (2009).Benton, M. J., Donoghue, P. C., Asher, R. J., Friedman, M., Near, T. J., & Vinther, J. (2015). "Constraints on the timescale of animal evolutionary history." ''Palaeontologia Electronica'', 18.1.1FC; 1-106; palaeo-electronica.org/content/fc-1 The

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 ...

here was modified after Muller and Reisz (2006):Muller, J. and Reisz, R.R. (2006). "The phylogeny of early eureptiles: Comparing parsimony and Bayesian approaches in the investigation of a basal fossil clade." ''Systematic Biology'', 55(3):503-511.

References

External links

Eureptilia
examples of some Permian species

{{Taxonbar, from=Q3060510 Tetrapod unranked clades Extant Pennsylvanian first appearances Taxa named by Everett C. Olson