Procolophonia
Encyclopedia
The Procolophonia are a suborder
of herbivorous
reptile
s 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 1988) but are now considered a clade of Parareptilia
. They are closely related to other generally lizard-like Permian reptiles such as the Millerettidae, Bolosauridae, Acleistorhinidae
, Lanthanosuchidae, and Nyctiphruretidae, all of which are included under the Anapsida or "Parareptiles" (as opposed to the Eureptilia
).
idae. Smaller groups like Rhipaeosauridae
and Sclerosauridae
might be placed in either superfamily, or prior to both, although according to the traditional classification of Carroll 1988 the Rhipaeosauridae are classified with the Pareiasaurs and the Sclerosaurs with the Procolophonids.
s, although experts disagree over whether turtle ancestors are to be sought among the Procolophonidae, the Pareiasauridae (Lee 1995,1996, 1997), or simply a generic Procolophonian ancestor. Laurin
& Reisz, 1995 and Laurin & Gauthier
1996 define the Procolophonia cladistically as "The most recent common ancestor of pareiasaurs, procolophonids, and testudines (Chelonia), and all its descendants", and list a number of autapomorphies
. However, Rieppel and deBraga 1996 and deBraga & Rieppel, 1997 argue that turtles evolved from Sauropterygia
ns, which would mean that the Parareptilia and Procolophonia constitute wholly extinct clades that are only distantly related to living reptiles. However this is still a topic of debate.
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
of herbivorous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s 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
Captorhinida
Captorhinida is a doubly paraphyletic grouping of early reptiles. Robert L. Carroll ranked it as an order in the subclass Anapsida, composed of the following suborders:...
Carroll 1988) but are now considered a clade of Parareptilia
Parareptilia
Parareptilia is a subclass or clade of reptiles which is variously defined as an extinct group of primitive anapsids, or a more cladistically correct alternative to Anapsida...
. They are closely related to other generally lizard-like Permian reptiles such as the Millerettidae, Bolosauridae, Acleistorhinidae
Acleistorhinidae
Acleistorhinidae is a family of Early Permian-aged parareptiles. Presently, the clade consists of only two taxa, Colobomycter and Acleistorhinus, both collected from the Permian of Oklahoma. Sister taxa include Nyctiphruretidae and Sclerosauridae....
, Lanthanosuchidae, and Nyctiphruretidae, all of which are included under the Anapsida or "Parareptiles" (as opposed to the Eureptilia
Eureptilia
Eureptilia is one of the two major clades of the Sauropsida, the other being Anapsida . Eureptilia includes not only all Diapsids, but also a number of primitive Permo-Carboniferous forms previously classified under the Anapsida, in the old order "Cotylosauria".Primitive eureptilians were all...
).
Subclassification
There are two main groups of Procolophonia, the small, lizard-like Procolophonoidea, and the Pareiasauroidea, which include the large, armoured PareiasaurPareiasaur
The Pareiasaurs - Family Pareiasauridae - are a clade of medium-sized to large herbivorous anapsid reptiles that flourished during the Permian period....
idae. Smaller groups like Rhipaeosauridae
Rhipaeosauridae
Rhipaeosauridae was a family of Procolophonids from the Permian time period.-Classification:Rhipaeosauridae was assigned to Cotylosauria by Tchudinov , to Pareiasauria by Olson , and to Pareiasauroidea by Carroll ....
and Sclerosauridae
Sclerosaurus
Sclerosaurus is an extinct genus of sauropsid....
might be placed in either superfamily, or prior to both, although according to the traditional classification of Carroll 1988 the Rhipaeosauridae are classified with the Pareiasaurs and the Sclerosaurs with the Procolophonids.
Relation to Turtles
The Procolophonia are traditionally thought to be ancestral to the turtleTurtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s, although experts disagree over whether turtle ancestors are to be sought among the Procolophonidae, the Pareiasauridae (Lee 1995,1996, 1997), or simply a generic Procolophonian ancestor. Laurin
Michel Laurin
Michel Laurin is a Canadian vertebrate paleontologist specialising in the origin and phylogeny of tetrapods, comparative biology and paleobiology. As an undergraduate he worked in the laboratory of Robert L. Carroll, and took his doctor thesis on the osteology of seymouriamorphs under Robert R....
& Reisz, 1995 and Laurin & Gauthier
Jacques Gauthier
Jacques Armand Gauthier is a vertebrate paleontologist, comparative morphologist, and systematist, and one of the founders of the use of cladistics in biology....
1996 define the Procolophonia cladistically as "The most recent common ancestor of pareiasaurs, procolophonids, and testudines (Chelonia), and all its descendants", and list a number of autapomorphies
Autapomorphy
In cladistics, an autapomorphy is a distinctive anatomical feature, known as a derived trait, that is unique to a given terminal group. That is, it is found only in one member of a clade, but not found in any others or outgroup taxa, not even those most closely related to the group...
. However, Rieppel and deBraga 1996 and deBraga & Rieppel, 1997 argue that turtles evolved from Sauropterygia
Sauropterygia
Sauropterygia were a group of very successful aquatic reptiles that flourished during the Mesozoic before they became extinct at the end of the era. They were united by a radical adaptation of their shoulder, designed to support powerful flipper strokes...
ns, which would mean that the Parareptilia and Procolophonia constitute wholly extinct clades that are only distantly related to living reptiles. However this is still a topic of debate.
External links
- Hallucicrania - Mikko's Phylogeny ArchiveMikko's Phylogeny ArchiveMikko's Phylogeny Archive is an amateur paleontology website maintained by Mikko Haaramo, a student at the University of Helsinki's Department of Geology, Division of Geology and Palaeontology....
- Basal Anapsids - PalaeosPalaeosPalaeos.com is a web site on biology, paleontology, cladistics and geology and which covers the history of Earth. The site is well respected and has been used as a reference by professional paleontologists such as Michael J. Benton, the professor of vertebrate palaeontology in the Department of...