Anapsid

Taxobox
name = Anapsids
fossil_range = Carboniferous - Recent

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image_width = 215px
image_caption = Anapsid skull
regnum = Animalia
phylum = Chordata
subphylum = Vertebrata
superclassis = Tetrapoda
classis = Sauropsida
subclassis = Anapsida
subclassis_authority = Osborn, 1903
subdivision_ranks = Orders
subdivision =
Testudines (Turtles, tortoises & terrapins) †Mesosauria †Procolophonomorpha †Captorhinida

An anapsid is an amniote whose skull does not have openings near the temples. [Pough, F. H. et al. (2002) "Vertebrate Life", 6th Ed. Prentice Hall Inc., Upper Saddle River, NJ. ISBN 0130412481]

While "anapsid reptiles" or "anapsida" are traditionally spoken of as if they were a coherent group, it has been suggested that several groups of reptiles that had anapsid skulls may be only distantly related: scientists still debate the exact relationship between the basal (original) reptiles which first appeared in the late Carboniferous, the various Permian reptiles which had anapsid skulls, and the Testudines (turtles, tortoises, and terrapins). Many modern paleontologists believe the Testudines are descended from diapsid reptiles which lost their temporal fenestrae, although that view is not generally accepted yet (see "Parareptilia" for details and references).

The only living reptiles with anapsid skulls are the Testudines. The earliest fossil testudines are from the Triassic, but they were already too like modern turtles to be near the start of their lineage - in particular they already had limb joints within the rib cage. The main article about Testudines covers the debate about their ancestry.

Most of the other reptiles with anapsid skulls, including the millerettids, nyctiphrurets, and pareiasaurs, became extinct in the late Permian period by the Permian-Triassic extinction event. But the procolophonids managed to survive into the Triassic.

References

ee also

* Parareptilia
* Diapsida
* Synapsida
* Euryapsida

External links

* [http://www.ucmp.berkeley.edu/anapsids/anapsida.html Introduction to Anapsida] from UCMP