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Tikiguania, "Triassic" squamate redated to Late Tertiary



From: Ben Creisler
bcreisler@gmail.com

A new online paper:

Mark N. Hutchinson, Adam Skinner and Michael S. Y. Lee (2012)
Tikiguania and the antiquity of squamate reptiles (lizards and snakes).
Biology Letters (advance online publication)
doi: 10.1098/rsbl.2011.1216
http://rsbl.royalsocietypublishing.org/content/early/2012/01/24/rsbl.2011.1216.abstract

Abstract

Tikiguania estesi is widely accepted to be the earliest member of
Squamata, the reptile group that includes lizards and snakes. It is
based on a lower jaw from the Late Triassic of India, described as a
primitive lizard related to agamids and chamaeleons. However,
Tikiguania is almost indistinguishable from living agamids; a combined
phylogenetic analysis of morphological and molecular data places it
with draconines, a prominent component of the modern Asian
herpetofauna. It is unlikely that living agamids have retained the
Tikiguania morphotype unchanged for over 216 Myr; it is much more
conceivable that Tikiguania is a Quaternary or Late Tertiary agamid
that was preserved in sediments derived from the Triassic beds that
have a broad superficial exposure. This removes the only fossil
evidence for lizards in the Triassic. Studies that have employed
Tikiguana for evolutionary, biogeographical and molecular dating
inferences need to be reassessed.