Living amniotes—including all mammals, birds, crocodilians, snakes, and turtles—comprise an extraordinarily varied array of more than 21,000 species. Found in every major habitat on earth, they possess a truly remarkable range of morphological, ecological, and behavioral adaptations. The fossil record of amniotes extends back three hundred million years and reveals much about modern biological diversity of form and function. A collaborative effort of twenty-four researchers, Amniote Paleobiology presents thirteen new and important scientific perspectives on the evolution and biology of this familiar group. It includes new discoveries of dinosaurs and primitive relatives of mammals; studies of mammalian chewing and locomotion; and examinations of the evolutionary process in plesiosaurs, mammals, and dinosaurs. Emphasizing the rich variety of analytical techniques available to vertebrate paleontologists—from traditional description to multivariate morphometrics and complex three-dimensional kinematics— Amniote Paleobiology seeks to understand how species are related to each other and what these relationships reveal about changes in anatomy and function over time. A timely synthesis of modern contributions to the field of evolutionary studies, Amniote Paleobiology furthers our understanding of this diverse group. Matthew T. Carrano is curator of dinosaurs in the Department of Paleobiology at the Smithsonian Institution. Richard Blob is assistant professor in the Department of Biological Sciences at Clemson University. Timothy J. Gaudin is associate professor in the Department of Biological and Environmental Sciences at the University of Tennessee at Chattanooga. John R. Wible is curator of mammals at the Carnegie Museum of Natural History. AMNIOTE PALEOBIOLOGY Perspectives on the Evolution of Mammals, Birds, and Reptiles The University of Chicago Press Copyright © 2006 The University of Chicago All right reserved. ISBN: 978-0-226-09478-6 Contents 1. Introduction Timothy J. Gaudin, Matthew T. Carrano, Richard W. Blob, and John R. Wible......................................................................................................................................................................1Part One: New Fossils and Phylogenies2. The Mandible of Whatcheeria deltae, an Early Tetrapod from the Late Mississippian of Iowa R. Eric Lombard and John R. Bolt..................................................................................................................................213. Theropod Dinosaurs from the Early Jurassic of Huizachal Canyon, Mexico Regina C. Munter and James M. Clark..................................................................................................................................................534. Herpetoskylax hopsoni, a New Biarmosuchian (Therapsida: Biarmosuchia) from the Beaufort Group of South Africa Christian A. Sidor and Bruce S. Rubidge.......................................................................................................765. The Postcranial Skeleton of Kayentatherium wellesi from the Lower Jurassic Kayenta Formation of Arizona and the Phylogenetic Significance of Postcranial Features in Tritylodontid Cynodonts Hans-Dieter Sues and Farish A. Jenkins Jr......................1146. The Phylogeny of Living and Extinct Armadillos (Mammalia, Xenarthra, Cingulata): A Craniodental Analysis Timothy J. Gaudin and John R. Wible................................................................................................................153Part Two: Large-Scale Evolutionary Patterns7. The Origins of High Browsing and the Effects of Phylogeny and Scaling on Neck Length in Sauropodomorphs J. Michael Parrish..................................................................................................................................2018. Body-Size Evolution in the Dinosauria Matthew T. Carrano....................................................................................................................................................................................................2259. Major Changes in the Ear Region and Basicranium of Early Mammals Guillermo W. Rougier and John R. Wible.....................................................................................................................................................269Part Three: Functional Morphology10. Shoulder Girdle and Forelimb in Multituberculates: Evolution of Parasagittal Forelimb Posture in Mammals Paul C. Sereno....................................................................................................................................31511. Tooth Orientation during Occlusion and the Functional Significance of Condylar Translation in Primates and Herbivores A. W. Crompton, Daniel E. Lieberman, and Sally Aboelela..............................................................................367Part Four: Ontogeny and Evolution12. Neote