The origin of snake feeding

Citation
Msy. Lee et al., The origin of snake feeding, NATURE, 400(6745), 1999, pp. 655-659
Citations number
25
Categorie Soggetti
Multidisciplinary,Multidisciplinary,Multidisciplinary
Journal title
NATURE
ISSN journal
00280836 → ACNP
Volume
400
Issue
6745
Year of publication
1999
Pages
655 - 659
Database
ISI
SICI code
0028-0836(19990812)400:6745<655:TOOSF>2.0.ZU;2-6
Abstract
Snakes are renowned for their ability to engulf extremely large prey, and t heir highly flexible skulls and extremely wide gape are among the most stri king adaptations found in vertebrates(1-5). However, the evolutionary trans ition from the relatively inflexible lizard skull to the highly mobile snak e skull remains poorly understood, as they appear to be fundamentally diffe rent and no obvious intermediate stages have been identified(4,5). Here we present evidence that mosasaurs-large, extinct marine lizards related to sn akes-represent a crucial intermediate stage. Mosasaurs, uniquely among liza rds, possessed long, snake-like palatal teeth for holding prey. Also, altho ugh they retained the rigid upper jaws typical of lizards, they possessed h ighly flexible lower jaws that were not only morphologically similar to tho se of snakes, but also functionally similar. The highly flexible lower jaw is thus inferred to have,evolved before the highly flexible upper jaw-in th e macrophagous common ancestor of mosasaurs and snakes-for accommodating la rge prey. The mobile upper jaw evolved later-in snakes-for dragging prey in to the oesophagus. Snakes also have more rigid braincases than lizards, and the partially fused meso- and metakinetic joints of mosasaurs are transiti onal between the loose joints of lizards and the rigid joints of snakes. Th us, intermediate morphologies in snake skull evolution should perhaps be so ught not in small burrowing lizards, as commonly assumed, but in large mari ne forms.