Parviraptor

Parviraptor is a genus of stem-snake (clade Ophidia)[1] containing one species, Parviraptor estesi, from the Late Jurassic (Tithonian) or Early Cretaceous (Berriasian) Purbeck Limestone Formation of Dorset, England.[1] A second species, Parviraptor gilmorei, was described from the Late Jurassic Morrison Formation of Western North America;[2] it was present in stratigraphic zone 4.[3] However, the second species was subsequently transferred to a separate genus Diablophis.[1]. An indeterminate species is known from the Bathonian aged Kirtlington Mammal Bed.

Parviraptor
Temporal range: Bathonian–Berriasian
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Clade: Ophidia
Genus: †Parviraptor
Evans, 1994
Type species
Parviraptor estesi
Evans, 1994

Description

The shape, length, and body form of Parviraptor and other early snakes is not currently known. Parviraptor is classified as a basal snake based on skull morphology. It shares most skull features with modern snakes, but notably does not have the lateral notches in the lower jaw found in modern snakes. Its vertebrae share all diagnostic features of later snakes. Analysis of Parviraptor fossils supports the hypothesis that snake ancestors evolved snakelike heads earlier than snakelike bodies.[1]

Phylogeny

Cladogram based in the phylogenetic analysis by Caldwell et al. (2015):[1]

Ophidia
 

Portugalophis

 
 

Parviraptor

 
 
 

Eophis

 
 
 

Unnamed sp.

 
 

Diablophis

 
 
 
 
 

Dinilysia

 
 
 

Madtsoiidae

 
 
 

Najash

 
 
 

Coniophis

 
 

Serpentes (Modern snakes)

 
 
 
 
 
 
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See also

References
  1. Caldwell, M. W.; Nydam, R. L.; Palci, A.; Apesteguía, S. N. (2015). "The oldest known snakes from the Middle Jurassic-Lower Cretaceous provide insights on snake evolution" (PDF). Nature Communications. 6: 5996. doi:10.1038/ncomms6996. PMID 25625704.
  2. Foster, J. (2007). "Table 2.1: Fossil Vertebrates of the Morrison Formation." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 58-59.
  3. Foster, J. (2007). "Enneabatrachus hechti" Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 137.


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