The skull of the gerrhonotine lizard Elgaria panamintina (Squamata: Anguidae).

David T Ledesma,Simon G Scarpetta,Jim Mead

doi:10.1371/journal.pone.0199584

David T Ledesma, Simon G Scarpetta + Show 1 more

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https://doi.org/10.1371/journal.pone.0199584

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Journal: PloS one	Publication Date: Jun 28, 2018
Citations: 13	License type: CC BY 4.0

Affiliation: The University of Texas at Austin

Abstract

We provide the first description of the skull, osteoderms, and hyoid apparatus of the poorly known alligator lizard Elgaria panamintina, and compare the cranial osteology of that species to the widespread and well-studied taxon Elgaria multicarinata. Patterns of morphological variation resulting from ontogenetic transformations and pathology are discussed. We employed x-ray computed tomography (CT) scans to examine two adult specimens of Elgaria panamintina and two adult specimens of Elgaria multicarinata, in addition to examining multiple traditionally prepared skeletal specimens of the latter species. CT scans provide simultaneous study of both articulated and disarticulated elements, allowing us to describe and document the morphology of the skull with exceptional precision and detail. The description of the skull of Elgaria panamintina serves as a generalization for all Elgaria; here we provide the first complete description of the skull of this genus for future uses in morphological and phylogenetic studies of both extant species and fossils.

Highlights

Lizards of the anguid clade Gerrhonotinae have been the subject of previous phylogenetic [1,2,3,4,5,6], paleontological [5, 7, 8], ecological [9], and biogeographic studies [10]
A large assemblage of fossil anguids and xenosaurids from the Eocene of Wyoming included specimens referred to Gerrhonotinae [26], and a comprehensive phylogenetic analysis of that assemblage and other extant and extinct Anguioidea produced a detailed description of the relationships and apomorphies of a sample of gerrhonotine lizard taxa
Recent work called into question the monophyly of Elgaria multicarinata [42], a close relationship between Elgaria panamintina and some subset of the Elgaria multicarinata complex likely still exists. Because of this close relationship we provide a comparison of the cranial osteology of Elgaria panamintina and Elgaria multicarinata

Summary

Introduction

Lizards of the anguid clade Gerrhonotinae have been the subject of previous phylogenetic [1,2,3,4,5,6], paleontological [5, 7, 8], ecological [9], and biogeographic studies [10]. There are six genera of extant gerrhonotine lizards, Abronia, Barisia, Coloptychon, Elgaria, Gerrhonotus, and Mesaspis [14]. Studies focused on the cranial osteology of gerrhonotine lizards were relatively limited in scope and included only a few species, usually using exemplars from commonly available taxa like Abronia deppii, Abronia oaxacae, Barisia imbricata, Elgaria multicarinata, Elgaria coerulea, Elgaria kingii, Gerrhonotus infernalis, and Gerrhonotus liocephalus. The most comprehensive study to date of gerrhonotine cranial osteology, which was conducted in a phylogenetic context, included 13 species from 5 genera [3]. A large assemblage of fossil anguids and xenosaurids from the Eocene of Wyoming included specimens referred to Gerrhonotinae [26], and a comprehensive phylogenetic analysis of that assemblage and other extant and extinct Anguioidea produced a detailed description of the relationships and apomorphies of a sample of gerrhonotine lizard taxa. Because of this close relationship we provide a comparison of the cranial osteology of Elgaria panamintina and Elgaria multicarinata

Methods

Discussion