Tuesday, November 2, 2010
Fossils + DNA Produce a New Squamate Tree
Wonambi usually considered a member of the extinct Madtsoiidae that first appears in the fossil record in late Cretaceous and extends to the late Pleistocene. The fossil family members have been found in South America, Africa, India, Southern Europe, and Australia. Madtsoiidae are known for a long, narrow skull; that are relatively inflexible upper jaws; a rounded snout; a braincase that narrows at the orbit and widens posteriorly,and elogated vertebrae. To date no evidence of hind limbs have been found.Wonambi reached an estimated length of 18 ft.
Dinilysia patagonica is known from the Cretaceous of Argentinia, South America and is considered closely allied to the extant anilioid snakes. Dinilysia is often compared to booids and it had a relatively large head, and is thought to have been terrestrial. Comparisons of the cranial anatomy of Dinilysia to the recently described hind-limbed, Argentine Gondwanan snake, Najash rionegrina suggest similarities in the two species, but hind limbs have not been found in Dinilysia. The evidence for a Gondwanaland origin of snakes is relatively strong.
John J. Wiens, Caitlin A. Kuczynski, Ted Townsend, Tod W. Reeder, Daniel G. Mulcahy, and Jack W. Sites, Jr. 2010. Combining Phylogenomics and Fossils in Higher-Level Squamate Reptile Phylogeny: Molecular Data Change the Placement of Fossil Taxa. Systematic Biolology doi:10.1093/sysbio/syq048