Extinct genus of reptiles
Sineoamphisbaena is an extinct genus of squamate of uncertain phylogenetic placement. Its fossils have been found in Late Cretaceous deposits in Inner Mongolia, China. It contains a single species, "Sineoamphisbaenia hexatabularis."
Taxonomic affiliation.
Wu "et al." and Gao proposed and argued that "Sineoamphisbaenia" was the oldest known amphisbaenian; this, however, was challenged by other authors, such as Kearney and Conrad, who instead assigned "Sineoamphisbaena" to the group of squamates variously known as Macrocephalosauridae, Polyglyphanodontidae or Polyglyphanodontia.
A large-scale study of fossil and living squamates published by Gauthier "et al." in 2012 did not find evidence for a particularly close relationship between amphisbaenians and "Sineoamphisbaena"; in their primary analysis "Sineoamphisbaena" was found to be the sister taxon of the clade containing snakes, amphisbaenians, the family Dibamidae and the American legless lizard. The primary analysis of Gauthier "et al." did not support a close relationship between "Sineoamphisbaena" and polyglyphanodontians either; however, the authors noted that when all snake-like squamates and mosasaurs were removed from the analysis, and burrowing squamates were then added individually to it, "Sineoamphisbaena" grouped with polyglyphanodontians. Gauthier "et al." considered it possible that "Sineoamphisbaena" was a burrowing polyglyphanodontian.
References.
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