The anatomy of the upper cretaceous snake Najash rionegrina Apesteguía & Zaher, 2006, and the evolution of limblessness in snakes |
| |
| Authors: | HUSSAM ZAHER SEBASTIÁN APESTEGUÍA CARLOS AGUSTÍN SCANFERLA |
| |
| Affiliation: | 1. Museu de Zoologia da Universidade de S?o Paulo, Avenida Nazaré 481, Ipiranga, S?o Paulo 04263‐000, S?o Paulo, Brazil;2. Fundación de Historia Natural ‘Felix Azara’ (CEBBAD), Universidad Maimónides, V. Virasoro 732, Buenos Aires (1405), Argentina;3. Laboratorio de Anatomía Comparada y Evolución de los Vertebrados. Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’. Av. Angel Gallardo 470 (1405), Buenos Aires, Argentina |
| |
| Abstract: | Najash rionegrina Apesteguía & Zaher, 2006 , a terrestrial fossil snake from the Upper Cretaceous of Argentina, represents the first known snake with a sacrum associated with robust, well‐developed hind limbs. Najash rionegrina documents an important gap in the evolutionary development towards limblessness, because its phylogenetic affinities suggest that it is the sister group of all modern snakes, including the limbed Tethyan snakes Pachyrhachis, Haasiophis, and Eupodophis. The latter three limbed marine fossil snakes are shown to be more derived morphologically, because they lack a sacrum, but have articulated lymphapophyses, and their appendicular skeleton is enclosed by the rib cage, as in modern snakes. |
| |
| Keywords: | serpentes systematics squamata |
|
|
