A Fossil Anolis Lizard Tail in Mexican Amber: Phylogenetic Relationships and Biogeographic Significance.

Pre-Pleistocene fossils of Anolis lizards from the mainland of the Americas are exceedingly rare: only two specimens referred to a single species have been described previously. Here we report on a third specimen, preserved (as are the other two) in Miocene amber from Chiapas, Mexico, and consisting primarily of the anterior vertebrae of the caudal sequence. Despite the fragmentary nature of the fossil, it preserves key osteological characters that permit confident referral to the Anolis clade and further suggest placement within the Dactyloa subclade in a clade of three extant species within the Anolis aequatorialis series. The Chiapan provenance of the fossil indicates that the geographic distribution of the Dactyloa clade (and possibly that of the A. aequatorialis series) extended considerably farther north during the Miocene. Although the new fossil represents a different part of the body than the two fossils representing the fossil species Anolis electrum, its inferred phylogenetic relationships are the same as one of the several possible phylogenetic relationships of that species and thus allow for the possibility that all three specimens belong to the same species. [ABSTRACT FROM AUTHOR]