Estudo comparativo de restos fósseis e recentes de Amphisbaenia: abordagens filogenéticas, paleoecológicas, paleobiogeográficas

• Autor(a) principal: Benites, João Paulo de Almeida [UNESP]
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/132538; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/21-12-2015/000855485.pdf
• topic: Vertebrates, Fossil; Vertebrado fossil; Filogenia; Paleoecologia; Paleobiogeografia

Amphisbaenia is an important group of reptilian amniotes, provided with cylindrical and elongated body, usually limbless, with the exception of the Family Bipedidae, which presents limbs. This anatomy facilitates fossorial life. They are allocated to Squamata, by having hemipenis, tooth to break the egg, cross cloacal vent and integument covered with scales. Resembling lacertilians and snakes, their phylogenetic position has been widely discussed and their ancestry is still controversial. They are limited to subtropical and tropical regions, providing important paleoecological and paleobiogeographical informations to the group. They cave deep tunnels, compacting soil, which implies major morphological changes, such as robust skull bones, with rigid plates, and strong osteological connections in the frontal region, with superimposed bones, giving them greater resistance to impacts during excavation. Their anatomy is quite convergent with Mesozoic lacertiform fossils, showing a probable common ancestor with these diapsids. A specimen of VIII Cryptolacerta, from Germany, shares features with Amphisbaenia. However its phylogeny is still uncertain. But Sineoamphisbaena may indicate convergent features between Laurasian lizards, possibly with those originated Amphisbaenia. The fossil records are geographically restricted, predominantly from USA, in relatively small quantity. Most are related to the Family Rhineuridae, which could be considered primitive. However the Family Bipedidae, a recent group, is classified also as primitive, due to the presence of shoulder girdle and forelimbs. But Bipedidae does not present fossils, because until now there are not fossilized remains assigned to them. Morphological convergence occurs in Rhineuridae, detailed in phylogenetic analyses, placing it as a apomorphic group. Anyway it is clear that the origin of Amphisbaenia remains obscure. There are not well preserved fossil materials before beginning of Eocene