Pachyrhachis

Pachyrhachis Temporal range: Late Cretaceous
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Subclass:	Diapsida
Order:	Squamata
Suborder:	Serpentes
Family:	Pachyophiidae
Genus:	Pachyrhachis
Species:	P. problematicus
Binomial name
Pachyrhachis problematicus

Pachyrhachis is an extinct genus of snake with well developed hind legs known from fossils discovered Ein Yabrud, near Ramallah, in the central West Bank. It is one of three genera of Cenomanian snakes with hindlimbs. Many of today's modern pythons and boas still have small bone spurs, where limbs would have been millions of years ago. Pachyrhachis snakes would have only been about 1 m (3-4 ft) long. Pachyrhachis was originally described by Haas (1979, 1980) who noted it had a puzzling melange of snake and lizard features; its status as a primitive snake was later confirmed (Caldwell and Lee 1997). The position of Pachyrhachis within snakes is debated (e.g. Lee and Scanlon 2002; Rieppel et al. 2003).

File:Http://www.tylertornado.com/pachyrhachis snake.jpg==See also== Other known fossil snakes with legs:

• Eupodophis
• Haasiophis
• Najash

External links

• Picture
• The Cenomanian: stage of hindlimbed snakes

Caldwell, M. W. & Lee, M. S. Y. (1997). A snake with legs from the marine Cretaceous of the Middle East. Nature 386: 705-709.

Haas, G. 1979 On a new snakelike reptile from the Lower Cenomanian of Ein Jabrud, near Jerusalem. Bull. Mus. Nat. Hist. Nat., Paris, Ser. 4, 1, 51-64.

Haas, G. 1980 Pachyrhachis problematicus Haas, snakelike reptile from the Lower Cenomanian: ventral view of the skull. Bull. Mus. Nat. Hist. Nat., Paris, Ser. 4, 2:87-104.

Haas, G. 1980 Remarks on a new ophiomorph reptile from the Lower Cenomanian of Ein Jabrud, Israel. In Aspects of Vertebrate History, in Honor of E.H. Colbert (ed. L.L. Jacobs), pp. 177-102. Flagstaff AZ: Museum of Northern Arizona Press.

Lee, M.S.Y. and Caldwell, M.W. 1998. Anatomy and relationships of Pachyrhachis, a primitive snake with hindlimbs. Philosophical Transactions of the Royal Society of London: Biological Sciences 353: 1521-1552.

Lee, M.S.Y., Scanlon, J.D. 2002. Snake phylogeny based on osteology, soft anatomy and behaviour. Biological Reviews 77: 333-401.

Rieppel, Olivier et al. 2003 "The Anatomy and Relationships of Haasiophis terrasanctus, a Fossil Snake with Well-Developed Hind Limbs from the Mid-Cretaceous of the Middle East" Journal of Paleontology 77(3):536-558

Scanlon, J.D., Lee, M.S.Y., Caldwell, M.W. and Shine, R. 1999. Paleoecology of the primitive snake Pachyrhachis. Historical Biology 13: 127-152.