Translator Disclaimer
13 September 2019 Flap-Footed Lizards (Gekkota: Pygopodidae) Have Forelimbs, Albeit During Embryonic Development
Author Affiliations +
Abstract

Limb reduction among squamate clades is common; limbless (forelimbs, hindlimbs, or both) forms have had at least 25 independent origins among snakes and lizards. The general evolutionary pattern is the gradual loss of limb elements proceeding from the toes to the shoulder or hip. In contrast, forelimbs are not known to have ever existed in snakes. Forelimbs are not known for either stem or crown snakes; snake fossils lack forelimbs and the embryos of modern snakes lack the signaling pathways that initiate forelimb development. Both fossil and developmental data thus imply an abrupt loss of forelimbs. In contrast, the well-developed hindlimbs of the oldest fossil snakes and vestigial hindlimbs of some basal clades of modern snakes imply the historical presence of hindlimbs, and their gradual reduction during snake evolution. In contrast, observations on limb-reduced lizards are in accord with gradual reduction of both fore- and hindlimbs; embryos of even limbless species initiate limb development. The question then arises, have any clades of limbless lizards become limbless abruptly, as have snakes? To address this question, I examined limb development in the family Pygopodidae. Like basal snakes, pygopodids are characterized by the absence of forelimbs and by vestigial hindlimbs. My observations on the development of forelimb buds in Delma molleri support gradual limb reduction, as do observations on other limbless lizards. Nonetheless, many clades of limbless lizards are yet to be studied and hence provide a wealth of opportunities to address modes of limb reduction and loss in squamate reptiles.

Copyright 2019 Society for the Study of Amphibians and Reptiles
Robin M. Andrews "Flap-Footed Lizards (Gekkota: Pygopodidae) Have Forelimbs, Albeit During Embryonic Development," Journal of Herpetology 53(3), 252-256, (13 September 2019). https://doi.org/10.1670/19-002
Accepted: 17 April 2019; Published: 13 September 2019
JOURNAL ARTICLE
5 PAGES


SHARE
ARTICLE IMPACT
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top