Paracryptodira

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Paracryptodira
Fossil range: Jurassic-Eocene

Manchurochelys liaoxiensis
(Baenoidea: Macrobaenidae)

Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Superclass:	Tetrapoda
Class:	Sauropsida
Subclass:	Anapsida
Order:	Testudines
Suborder:	Cryptodira
Infraorder:	Paracryptodira Gaffney, 1975

Superfamilies

Baenoidea
and see text

Synonyms

Pleurosternoidea

The Paracryptodira are an extinct infraorder of the Testudines, an order of reptiles which includes tortoises, turtles and terrapins. Initially treated as suborder sister to the Cryptodira^[1], they are now known to be a very primitive lineage inside the Cryptodira according to the most common use of the latter taxon^[2]. Some less primitive prehistoric cryptodires (e.g. the "horned turtles", Meiolaniidae) as well as the living forms make up the Eucryptodira^[3].

Paracryptodires according to the obsolete concept were made up of two Cretaceous families, the Pleurosternidae and Baenidae. The former has been found in North America, Europe, and possibly Asia, while the latter is only known to have occurred in North America. According to modern understanding however, the Macrobaenidae and the Neurankylidae are split from the Baenidae to form the superfamily Baenoidea, whose monophyly needs confirmation however. In addition, there are a number of more basal families as well as some of uncertain position with regards to the Baenoidea:^[4]

Kallokibotiidae
Mongolochelyidae
Pleurosternidae
Solemydidae

The Macrobaenidae, another prehistoric cryptodiran group that may actually be a paraphyletic assemblage, are sometimes placed entirely or partly in the paracryptodires too.

[edit] Characteristics

Paracryptodira have reduced prefrontal exposure on the dorsal surface of the skull, reduced fenestra perilymphatica, and a secondary reduced supraoccipital crest. ^[2]. In the skull, the posterior foramen for the internal carotid canal is located midway along the basisphenoidpterygoid suture^[1].

[edit] Footnotes

^ ^a ^b Gaffney (1975)
^ ^a ^b Joyce (2007)
^ See references in Haaramo (2008)
^ Joyce (2007) and see references in Haaramo (2008)

[edit] References

Gaffney, E.S. (1975): A phylogeny and classification of higher categories of turtles. Bulletin of the American Museum of Natural History 155(5): 387-436. PDF fulltext
Haaramo, Mikko (2008): Mikko's Phylogeny Archive - Paracryptodira. Version of 2008-MAR-11. Retrieved 2008-MAY-06.
Joyce, W.G. (2007): Phylogenetic relationships of Mesozoic turtles. Bulletin of the Peabody Museum of Natural History 48(1): 3–102. DOI:10.3374/0079-032X(2007)48[3:PROMT]2.0.CO;2 HTML abstract