Fossil of '' Labidosaurus hamatus'' Captorhinida (older name: Cotylosauria) is a doubly

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

grouping of early

reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...

Robert L. Carroll Robert "Bob" Lynn Carroll (May 5, 1938 – April 7, 2020) was an American–Canadian vertebrate paleontologist who specialised in Paleozoic and Mesozoic amphibians and reptiles. Biography Carroll was an only child and grew up on a farm nea ...

(1988) ranked it as an order in the subclass

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

a, composed of the following suborders:R. L. Carroll (1988), ''

Vertebrate Paleontology and Evolution ''Vertebrate Paleontology and Evolution'' is an advanced textbook on vertebrate paleontology by Robert L. Carroll, published in 1988 by WH Freeman. It provides a very detailed technical account of various groups of living and fossil vertebrate ...

'', W. H. Freeman and Company, New York * A paraphyletic Captorhinomorpha, containing the families

Protorothyrididae Protorothyrididae is an extinct family (biology), family of small, lizard-like reptiles belonging to Eureptilia. Their skulls did not have Fenestra (anatomy), fenestrae, like the more derived diapsids. Protorothyridids lived from the Late Carbon ...

Captorhinidae Captorhinidae is an extinct family of tetrapods, traditionally considered primitive Reptile, reptiles, known from the late Carboniferous to the Late Permian. They had a cosmopolitan distribution across Pangea. Description Captorhinids are a cl ...

, Bolosauridae,

Acleistorhinidae Acleistorhinidae is an extinct family of Late Carboniferous and Early Permian-aged ( Moscovian to Kungurian stage) parareptiles. It is defined as a node based clade including the last common ancestor of '' Acleistorhinus pteroticus'' and '' Co ...

and possibly also Batropetidae *

Procolophonia Procolophonia is an extinct suborder (clade) of herbivorous reptiles that lived from the Middle Permian till the end of the Triassic period. They were originally included as a suborder of the Cotylosauria (later renamed Captorhinida Carroll ...

, containing families

Nyctiphruretidae Nyctiphruretidae is an extinct family of hallucicranian parareptiles known from the late Early to the late Middle Permian of European Russia and south-central United States. Nyctiphruretidae was named by Efremov in 1938. The type genus is '' N ...

Procolophonidae Procolophonidae is an extinct family (biology), family of small, lizard-like parareptiles known from the Late Permian to Late Triassic that were distributed across Pangaea, having been reported from Europe, North America, China, South Africa, Sou ...

and

Sclerosauridae Procolophonidae is an extinct family of small, lizard-like parareptiles known from the Late Permian to Late Triassic that were distributed across Pangaea, having been reported from Europe, North America, China, South Africa, South America, Antarc ...

Pareiasauroidea Pareiasaurs (meaning "cheek lizards") are an extinct clade of large, herbivorous parareptiles. Members of the group were armoured with osteoderms which covered large areas of the body. They first appeared in southern Pangea during the Middle Per ...

, with families

Rhipaeosauridae Nycteroleteridae is a family of procolophonian parareptilians (extinct early reptiles) from the Middle to Late Permian of Russia and North America. They are sometimes classified as a sister group to pareiasaurids (but see ''Classification)''. Th ...

and

Pareiasauridae Pareiasaurs (meaning "cheek lizards") are an extinct clade of large, herbivorous parareptiles. Members of the group were armoured with osteoderms which covered large areas of the body. They first appeared in southern Pangea during the Middle Per ...

Millerosauroidea Millerosauria is an order of Parareptiles that contains the families †Millerettidae and † Eunotosauridae. It is the sister group to the order Procolophonomorpha. It was named in 1957 by Watson. It was once considered a suborder of the disus ...

, with a single family

Millerettidae Millerettidae is an extinct family of parareptiles from the Middle Permian to the Late Permian period ( Capitanian - Changhsingian stages) of South Africa. The millerettids were small insectivores and probably resembled modern lizards in appea ...

. While they all share primitive features and resemble the ancestors of all modern reptiles, some of these families are more closely related to (or belong to) the clade

Parareptilia Parareptilia ("near-reptiles") is an extinct group of basal sauropsids (" reptiles"), traditionally considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds). Parareptiles first arose near the en ...

, while others are further along the line leading to

diapsid 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 earliest traditionally identified diapsids, the araeosc ...

s. For this reason, the group is only used informally, if at all, by most modern paleontologists. All members of this group are thought to be extinct.

References

Prehistoric reptile taxonomy Prehistoric tetrapod orders Paraphyletic groups {{Paleo-reptile-stub