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Permanent link (DOI): https://doi.org/10.7939/R3Z63R

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Systematics of Platynotan Lizards Open Access

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Other title
Subject/Keyword
Morphology
Anguimorpha
Platynota
Necrosauridae
Phylogeny
Systematics
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Barr, Braden N.
Supervisor and department
Caldwell, Michael (Biological Sciences)
Examining committee member and department
Holmes, Robert (Biological Sciences)
Nydam, Randall (Anatomy, Midwestern University)
Larsson, Hans (Redpath Museum, McGill University)
Proctor, Heather (Biological Sciences)
Lemelin, Pierre (Medicine and Dentistry)
Department
Department of Biological Sciences
Specialization
Systematics and Evolution
Date accepted
2012-09-27T09:12:08Z
Graduation date
2012-09
Degree
Doctor of Philosophy
Degree level
Doctoral
Abstract
Living platynotan lizards are represented by two families: Helodermatidae, consisting of two species limited to south-western North America and north-western Central America; and Varanidae, with 54 species distributed throughout Africa, south-east Asia and Australia. Modern members of Platynota, universally adapted to a predaceous lifestyle and often specializing in relatively large vertebrate prey, include the largest living lizard and three species known to employ venom. Although relatively depauperate, in terms of extant taxa, the 100 million year record of fossil Platynota reveals a widely distributed and morphologically diverse clade of predatory lizards. Several new taxa have been introduced in the past 30 years, many represented by complete skulls and skeletons yet the relationships among taxa found at the base of Platynota remain largely unresolved. Many basal platynotans have been placed within family Necrosauridae, the type genus of which is the most widely distributed and well represented fossil platynotan. As currently constituted the Necrosauridae is presumed to be paraphyletic and lacks a clear and concise diagnosis as does the type genus Necrosaurus. Amended diagnoses are provided for Necrosaurus and the Necrosauridae and the membership of taxa previously placed within Necrosauridae is examined. Phylogenetic analysis of fossil platynotans recovers a monophyletic Necrosauridae in a sister-group relationship to a clade containing modern varanids. Description of a new genus and species of platynotan from the Maastrichtian of southern Saskatchewan reveals unusual anatomical features, adding to the already diverse morphology represented within Platynota. The newly described species is the oldest member of the Necrosauridae and one of two North American species.
Language
English
DOI
doi:10.7939/R3Z63R
Rights
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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