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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, whose relationships to other reptilian groups are still uncertain.

Parareptiles
Temporal range: Asselian - Rhaetian, 298.9–201.3 Ma
Bradysaurus im NHM Wien.JPG
Skeleton of a parareptile (Bradysaurus baini)
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Parareptilia
Olson, 1947
Orders

History of classificationEdit

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 those anapsids that were thought to be unrelated to turtles. Gauthier et al. 1988 provided the first phylogenetic definitions for the names of many amniote taxa and argued 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 found a different cladogram, in which Reptilia were divided into Parareptilia (now a formal taxon they defined as "Testudines and all amniotes more closely related to them than to diapsids.") and Eureptilia. Captorhinidae was transferred to Eureptilia, and Parareptilia included both early anapsid reptiles and turtles. The mesosaurs were placed outside both groups, as the sister group to the reptiles (but still sauropsids). The traditional group Anapsida was rejected as paraphyletic. This gave the following result:


Amniota 

Synapsida 

 Sauropsida 

Mesosauridae 

 Reptilia 
 Parareptilia 

Millerettidae 

 Procolophonia 

Pareiasauria 

 Testudinomorpha 

Procolophonidae 

Testudines 

 Eureptilia 

Captorhinidae 

Romeriida

Protorothyrididae 

Diapsida 

In contrast, Rieppel, 1994, 1995; Rieppel & deBraga, 1996; and deBraga & Rieppel, 1997 argued that turtles are actually related to the sauropterygians, and 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). The first genome-wide phylogenetic analysis was completed by Wang et al. (2013). Using the draft genomes of Chelonia mydas and Pelodiscus sinensis, the team used the largest turtle data set to date in their analysis and concluded that turtles are likely a sister group of crocodilians and birds (Archosauria).[1] This placement within the diapsids suggests that the turtle lineage lost diapsid skull characteristics as it now possesses an anapsid skull. This would make Parareptilia a totally extinct group with skull features that coincidentally resemble those of turtles.

The cladogram below follows an analysis by M.S. Lee, in 2013.[2]

Amniota 

Synapsida 

 Sauropsida 
 Parareptilia 

Millerettidae 

Eunotosaurus

 Hallucicrania 

Lanthanosuchoidea 

Procolophonia

Procolophonoidea 

Pareiasauromorpha 

 Eureptilia 

Captorhinidae 

 Romeriida 

Paleothyris

 Diapsida 

Araeoscelidia 

 Neodiapsida 

Claudiosaurus 

Younginiformes 

Lepidosauromorpha 

 Archosauromorpha 

Choristodera 

Trilophosaurus 

Rhynchosauria 

Archosauriformes 

 Sauropterygia 

Eosauropterygia 

Placodontia 

Sinosaurosphargis

Odontochelys

Proganochelys

Testudines 

ReferencesEdit

  1. ^ Wang, Zhuo; Pascual-Anaya, J; Zadissa, A; Li, W; Niimura, Y; Huang, Z; Li, C; White, S; Xiong, Z; Fang, D; Wang, B; Ming, Y; Chen, Y; Zheng, Y; Kuraku, S; Pignatelli, M; Herrero, J; Beal, K; Nozawa, M; Li, Q; Wang, J; Zhang, H; Yu, L; Shigenobu, S; Wang, J; Liu, J; Flicek, P; Searle, S; Wang, J; et al. (27 March 2013). "The draft genomes of soft-shell turtle and green sea turtle yield insights into the development and evolution of the turtle-specific body plan". Nature Genetics. 45 (701–706): 701–6. doi:10.1038/ng.2615. PMC 4000948. PMID 23624526.
  2. ^ Lee, M. S. Y. (2013). "Turtle origins: Insights from phylogenetic retrofitting and molecular scaffolds". Journal of Evolutionary Biology. 26 (12): 2729–2738. doi:10.1111/jeb.12268. PMID 24256520.
  • Katsu, Y.; Braun, E. L.; Guillette, L. J. Jr.; Iguchi, T.; Guillette (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.CS1 maint: multiple names: authors list (link)

External linksEdit