Parareptiles

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Parareptiles
Skeletal reconstruction of Bradysaurus

Skeletal reconstruction of Bradysaurus

Temporal occurrence
Upper Carboniferous to Upper Triassic
303.7 to 208.5 million years
Locations
  • worldwide
Systematics
Jaw mouths (Gnathostomata)
Land vertebrates (Tetrapoda)
Reptiliomorpha
Amniotes (Amniota)
Sauropsida
Parareptiles
Scientific name
Parareptilia
Olson , 1947

Parareptiles are an extinct group of reptiles that arose from a first diversification of the higher terrestrial vertebrates in the early Upper Carboniferous , but with the genus Erpetonyx is only documented by fossil finds from the most recent Upper Carboniferous and survived with the Procolophonids until the end of the Triassic .

In tribal history , parareptiles are defined as the least exclusive community of descent to which Milleretta rubidgei and Procolophon trigoniceps belong, but not Captorhinus aguti (see Tsuji and Müller, 2009). The sister group of the parareptiles are the eureptiles , to which the groups of scale reptiles , crocodiles and birds that live today also belong. The position of the tortoises (Testudinata) in the reptile system is uncertain.

features

Skulls and skull drawings of two representatives of the "Nycteroleteridae": Bashkyroleter (above) and Macroleter (below), both from the Permian of Russia.

Diagnostic features of parareptiles are (according to Müller and Tsuji 2007; Tsuji and Müller 2009), among other things , the lack of contact between the lacrimal and the nasal opening, the lack of a canine region , a single, centrally located indentation on the posterior edge of the cranium, and the lack of a supra glenoid opening , the lack of a subtemporal process on the jugal , the firm contact of the prefrontal to the palatine , a square jugal that is elongated on the abdomen , and the position of the temporomandibular joint at the level of the occiput or a little behind it.

The parareptiles are very diverse and include both the aquatic mesosaurs and fully terrestrial groups such as the massively built pareiasaurs and the lizard-like bolosaurids , milerettids , " nycteroleterids " and procolophonoids . While some groups such as the Millerettidae were probably insectivores (larger "Nycteroleteridae" such as Macroleter , probably even carnivores) and the mesosaurs ate fish and aquatic arthropods , bolosaurids, procolophonoids and pareiasaurs are interpreted as herbivores due to their teeth (see Benton 2005, Pp. 113-118).

Family relationships

Mesosaurus , the first aquatic reptile in geological history (Lower Permian, southern Africa and South America).
Procolophon , a Triassic parareptile.
Lanthanosuchus , an amphibian-like representative from the Permian of Russia.
Eudibamus , a bolosaur from the Lower Permian of Thuringia.

The following cladogram shows the relationships of the parareptiles according to Tsuji and Müller (2009). The subdivision of the eureptiles follows Laurin and Reisz (1995) (see also Benton, 2005).

  Amniota  

 Synapsida (including mammals )


  Reptilia  
  Parareptilia  

 Mesosauridae


   


 Millerettidae


   

 Eunotosaurus



  Ankyramorpha  

 Lanthanosuchoidea


   

 Nyctiphruretus


   

 Bolosauridae


   

 Procolophonoidea


   

 Pareiasauria


   

 " Nycteroleteridae "




Template: Klade / Maintenance / 3




  Eureptilia 

 Captorhinidae


   

 Paleothyris


   

 Diapsida (including today's reptile groups and birds )






Template: Klade / Maintenance / Style

The group of reptiles (Reptilia) includes, according to the definition of Modesto and Anderson (2004), today's reptile groups and all animals that are more closely related to them than to mammals. Synonymous with Reptilia , Sauropsida is also used as a group name. The position of Eunotosaurus next to the Milleretidae is uncertain, osteological findings indicate a closer relationship with the turtles , which have generally been known as diapsids (and thus eureptiles) since 2010 at the latest .

Ancestral group of turtles?

The anatomy of the turtles, which differs significantly from other reptile groups today , including the anapsid skull, i. H. a skull without temporal openings gave and still gives cause for some paleontologists to believe that these special features are due to an early separation of the trunk lines of the tortoises and the diapsids living today and that the parareptiles are the closest fossil relatives of the tortoises . Procolophonids (Laurin and Reisz, 1995) as well as pareiasaurs (see e.g. Lee 1997) and more recently Eunotosaurus (Lyson et al., 2010) were previously considered possible parareptile sister groups of the turtles .

For the corresponding clade (parareptiles including turtles) the name Anapsida was meanwhile in use (Modesto, 1999).

It is doubtful that osteological similarities that point to a relationship between the turtles and the parareptiles actually represent homologous features (see Rieppel and Reisz 1999; Rieppel 2000) and particularly molecular biological findings point to a position of the turtles within the diapsids (Zardoya and Meyer 1998, Cao et al. 2000). In addition, there is hardly any bone histological correspondence between the skin bone plates ( osteoderms ) of the pareiasaurs and the turtle shells , which histologically resemble the skin ossification of the diapsids (Scheyer and Sander 2009).

literature

Web links

Commons : Parareptilia ( Parareptilia )  - collection of images, videos and audio files

Individual evidence

  1. ↑ Sean P. Modesto, Diane M. Scott, Mark J. MacDougall, Hans-Dieter Sues, David C. Evans, Robert R. Reisz: The oldest parareptile and the early diversification of reptiles. Proceedings of the Royal Society B. Vol. 282, No. 1801, 2015, doi : 10.1098 / rspb.2014.1912 .
  2. ^ Tyler R. Lyson, Gabe S. Bever, Torsten M. Scheyer, Allison Y. Hsiang, Jacques A. Gauthier: Evolutionary Origin of the Turtle Shell. In: Current Biology. Vol. 23, No. 12, 2013, ISSN  0960-9822 , pp. 1113–1119, doi : 10.1016 / j.cub.2013.05.003 .