Field of Science

Tikiguania Is Not From the Triassic

Hutchinson, M. H., Skinner, A., and M. S. Y. Lee. 2012. Tikiguania and the antiquity of squamate reptiles (lizards and snakes). Biology Online published before print. doi: 10.1098/rsbl.2011.1216

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.                 

1 comment:

  1. If one accepts that Jesairosaurus, drepanosaurs, langobardisaurs, macrocnemids, Tanystropheus, Sharovipteryx, Longisquama, basal pterosaurs are lizards or lizard sisters then there is plenty of fossil evidence for them in the Triassic. Sure they're not Iguania + Scleroglossa, but they do descend from a sister to Huehuecuetzpalli, Meyasaurus and Lacertulus (Late Permian). More on those nestings here: www.reptileevolution.com/reptile-tree.htm

    ReplyDelete

Markup Key:
- <b>bold</b> = bold
- <i>italic</i> = italic
- <a href="http://www.fieldofscience.com/">FoS</a> = FoS