Parareptilia

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Parareptiles
Temporal range:
Possible descendant taxon Testudines survives to Present
Bradysaurus im NHM Wien.JPG
Skeleton of the parareptile Bradysaurus baini
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Sauropsida
Stem: Parareptilia
Olson, 1947
Orders

Mesosauria

Millerosauria

Procolophonomorpha

and see cladograms below

Parareptilia ("at the side of reptiles") 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. Whether the term is valid depends on the phylogenetic position of turtles, the relationships of which to other reptilian groups are still uncertain.

The name Parareptilia was coined by Olson in 1947 to refer to an extinct group of Paleozoic reptiles, as opposed to the rest of the reptiles or Eureptilia ("true reptiles").

Life restoration of Nyctiphruretus acudens

The name fell into disuse until it was revived by cladistic studies, to refer to anapsids that were thought unrelated to turtles. Gauthier et al. 1988 provided the first phylogenetic definitions for the names of many amniote taxa, including Sauropsida as the parent clade for Reptilia, and argued cladistically that captorhinids and turtles were sister groups, constituting the clade Anapsida (in a much more limited context than the definition given by Romer in 1967). A name had to be found for various Permian and Triassic reptiles no longer included in the anapsids, and "parareptiles" was chosen. However, they did not feel confident enough to erect Parareptilia as a formal taxon. Their cladogram was as follows:

AMNIOTA 

Synapsida


 Sauropsida 
 "Parareptiles" 

Mesosauridae




Procolophonidae




Millerettidae




Pareiasauria






 Reptilia 
 Anapsida 

Captorhinidae



Testudines



 Romeriida 

Protorothyrididae



Diapsida






Laurin and Reisz 1995 presented a different cladogram, in which Reptilia is divided into Parareptilia (now a formal taxon) and Eureptilia. Captorhinidae is transferred to Eureptilia, and Parareptilia includes both early anapsid reptiles and turtles, but not Captorhinidae and Protorothyrididae. The mesosaurs are placed outside both groups, as the sister taxon to the reptiles (but still sauropsids). The traditional taxon of Anapsida is rejected as paraphyletic. This gives the following:

AMNIOTA 

Synapsida


 Sauropsida 

Mesosauridae


 Reptilia 
 Parareptilia 

Millerettidae


 Procolophonia 

Parieasauria


 Testudinomorpha 

Procolophonidae




Testudines






 Eureptilia 

Captorhinidae


Romeriida

Protorothyrididae



Diapsida







In contrast, Rieppel, 1994, 1995; Rieppel & deBraga, 1996; and deBraga & Rieppel, 1997 have argued that turtles are actually related to Sauropterygia, and hence are diapsids. The diapsid affinities of turtles have been supported by molecular phylogenies (e.g. Zardoya and Meyer 1998; Iwabe et al., 2004; Roos et al., 2007; Katsu et al., 2010). This would make Parareptilia a wholly extinct clade. However this hypothesis has not been accepted by all vertebrate paleontologists, and Benton 2000, 2004, retained the traditional class Anapsida for the "parareptiles" and turtles.

See also[edit]

References[edit]

  • Gauthier, J.; A. G. Kluge, & T. Rowe (1988). "The early evolution of the Amniota". In M. J. Benton (ed.). The phylogeny and classification of the tetrapods, Volume 1: amphibians, reptiles, birds. 103-155. Oxford: Clarendon Press. 
  • Katsu, Y.; Braun, E. L.; Guillette, L. J. Jr.; Iguchi, T. (2010-03-17). "From reptilian phylogenomics to reptilian genomes: analyses of c-Jun and DJ-1 proto-oncogenes". Cytogenetic and Genome Research 127 (2–4): 79–93. doi:10.1159/000297715. PMID 20234127. 
  • Rieppel, O. (1994). "Osteology of Simosaurus gaillardoti and the relationships of stem-group sauropterygia". Fieldiana Geology 1462: 1–85. ISSN 0096-2651. 
  • Rieppel, O. (1995). "Studies on skeleton formation in reptiles: implications for turtle relationships". Zoology-Analysis of Complex Systems 98: 298–308. 
  • Rieppel, O.; deBraga, M. (1996). "Turtles as diapsid reptiles". Nature 384 (6608): 453–455. doi:10.1038/384453a0. 

External links[edit]