The ossified braincase and cephalic osteoderms of Shinisaurus crocodilurus (Squamata, Shinisauridae)

Gabe S. Bever, Christopher J. Bell, Jessica A. Maisano

Research output: Contribution to journalReview articlepeer-review

Abstract

We review the literature and provide a detailed description of the braincase, cephalic osteoderms, and the inner ear cavity of the rare Southeast Asian lizard Shinisaurus crocodilurus. In addition to standard dry skeletal preparations, we used X-ray, computed tomography scans of an adult and juvenile specimen to provide novel illustrations and digital animations of its anatomical systems. We provide the first detailed description and illustration of the orbitosphenoids, cephalic osteoderms, and inner ear passages in S. crocodilurus, clarify the presence or absence of previously reported anatomical features of the braincase, and provide preliminary observations on morphological change of the braincase through ontogeny. Orbitosphenoids are present and ossified in S. crocodilurus at a relatively early stage of postnatal development. A fully developed and ossified parasphenoid rostrum is present in our youngest dried specimen, but appears to be reduced or broken in many adult specimens. The osteoderms of adult S. crocodilurus are robust and widely distributed across the dorsal surface of the head, but they do not co-ossify with underlying dermal bones. Osteoderms are absent in our juvenile specimens. Calcified endolymph is present in both adult and juvenile specimens, but is more extensive in the juvenile. Our preliminary observations suggest that ontogenetic change is an important source of variation in S. crocodilurus.

Original languageEnglish (US)
JournalPalaeontologia Electronica
Volume8
Issue number1
StatePublished - Nov 9 2005
Externally publishedYes

Keywords

  • Anatomy
  • Braincase
  • Crocodile lizard
  • Krokodilschwanz-Höckerechse
  • Osteoderms, inner ear
  • Osteology
  • Shinisaurus

ASJC Scopus subject areas

  • Oceanography

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