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

Sauropsida Sauropsida ("lizard faces") is a clade of Amniote, amniotes, broadly equivalent to the Class (biology), class Reptile, Reptilia. Sauropsida is the Sister group, sister taxon to Synapsid, Synapsida, the other clade of amniotes which includes Mammal ...

, 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 the ...

. Eureptilia includes

Diapsida Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The group first appeared about three hundred million years ag ...

(the clade containing all modern

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates ( lizards and snakes) and rhynchoce ...

s and birds), as well as a number of primitive Permo-

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferous ...

forms previously classified under

Anapsida An anapsid is an amniote whose skull lacks one or more skull openings (fenestra, or fossae) near the temples. Traditionally, the Anapsida are the most primitive subclass of amniotes, the ancestral stock from which Synapsida and Diapsida evolved, ...

, in the old (no longer recognised) order "

Cotylosauria Fossil of '' Labidosaurus hamatus'' Captorhinida (older name: Cotylosauria) is a doubly paraphyletic grouping of early reptiles. Robert L. Carroll (1988) ranked it as an order in the subclass Anapsida, composed of the following suborders:R. L. Car ...

". 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, th ...

having greatly reduced

supraoccipital The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cere ...

, 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 later ...

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 ve ...

. 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 Cap ...

, 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 it ...

'' and "

protorothyrids Protorothyrididae is an extinct family of small, lizard-like reptiles belonging to Eureptilia. Their skulls did not have fenestrae, like the more derived diapsids. Protorothyridids lived from the Late Carboniferous to Early Permian periods, in w ...

" 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 we ...

. One primitive eureptile, the Late Carboniferous "protorothyrid" ''

Anthracodromeus ''Anthracodromeus'' is an extinct genus of Late Carboniferous (late Westphalian stage) " protorothyridid" eureptile known from Ohio. It is known from the holotype AMNH 6940, a nearly complete skeleton. It was collected in the Linton site i ...

,'' is the oldest known climbing 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 ''Petrolacosaurus'' ("rock lake lizard") is an extinct genus of diapsid reptile from the late Carboniferous period. It was a small, long reptile, and the earliest known reptile with two temporal fenestrae (holes at the rear part of the skull). T ...

'' 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