| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
© 2005 Society of Systematic Biologists
Integration of Morphological Data Sets for Phylogenetic Analysis of Amniota: The Importance of Integumentary Characters and Increased Taxonomic Sampling
Department of Anatomical Sciences, Stony Brook University Stony Brook, New York, 11794–8081 USA
Edited by Norman MacLeod: Associate Editor
 |
Abstract |
|---|
Several mutually exclusive hypotheses have been advanced to explain the phylogenetic position of turtles among amniotes. Traditional morphology-based analyses place turtles among extinct anapsids (reptiles with a solid skull roof), whereas more recent studies of both morphological and molecular data support an origin of turtles from within Diapsida (reptiles with a doubly fenestrated skull roof). Evaluation of these conflicting hypotheses has been hampered by nonoverlapping taxonomic samples and the exclusion of significant taxa from published analyses. Furthermore, although data from soft tissues and anatomical systems such as the integument may be particularly relevant to this problem, they are often excluded from large-scale analyses of morphological systematics. Here, conflicting hypotheses of turtle relationships are tested by (1) combining published data into a supermatrix of morphological characters to address issues of character conflict and missing data; (2) increasing taxonomic sampling by more than doubling the number of operational taxonomic units to test internal relationships within suprageneric ingroup taxa; and (3) increasing character sampling by approximately 25% by adding new data on the osteology and histology of the integument, an anatomical system that has been historically underrepresented in morphological systematics. The morphological data set assembled here represents the largest yet compiled for Amniota. Reevaluation of character data from prior studies of amniote phylogeny favors the hypothesis that turtles indeed have diapsid affinities. Addition of new ingroup taxa alone leads to a decrease in overall phylogenetic resolution, indicating that existing characters used for amniote phylogeny are insufficient to explain the evolution of more highly nested taxa. Incorporation of new data from the soft and osseous components of the integument, however, helps resolve relationships among both basal and highly nested amniote taxa. Analysis of a data set compiled from published sources and data original to this study supports monophyly of Amniota, Synapsida, Reptilia, Parareptilia, Eureptilia, Eosuchia, Diapsida, Neodiapsida, Sauria, Lepidosauria, and Archosauriformes, as well as several more highly nested divisions within the latter two clades. Turtles are here resolved as the sister taxon to a monophyletic Lepidosauria (squamates + Sphenodon), a novel phylogenetic position that nevertheless is consistent with recent molecular and morphological studies that have hypothesized diapsid affinities for this clade.
Keywords: Amniota; integument; osteoderms; phylogeny; Testudines
Received June 7, 2004; Revised August 16, 2004; Accepted December 10, 2004
Current Address: Department of Anatomy, New York College of Osteopathic Medicine, Northern Boulevard, Old Westbury, New York, 11568, USA; E-mail: rhill01{at}nyit.edu
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  S. R. Singer, S. L. Maki, A. D. Farmer, D. Ilut, G. D. May, S. B. Cannon, and J. J. Doyle Venturing Beyond Beans and Peas: What Can We Learn from Chamaecrista? Plant Physiology, November 1, 2009; 151(3): 1041 - 1047. [Full Text] [PDF]
|
|
|
|
 |
|
 W. G Joyce, S. G Lucas, T. M Scheyer, A. B Heckert, and A. P Hunt A thin-shelled reptile from the Late Triassic of North America and the origin of the turtle shell Proc R Soc B, February 7, 2009; 276(1656): 507 - 513. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. T. Butcher and R. W. Blob Mechanics of limb bone loading during terrestrial locomotion in river cooter turtles (Pseudemys concinna) J. Exp. Biol., April 15, 2008; 211(8): 1187 - 1202. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. J. Asher, J. H. Geisler, and M. R. Sanchez-Villagra Morphology, Paleontology, and Placental Mammal Phylogeny Syst Biol, April 1, 2008; 57(2): 311 - 317. [Full Text] [PDF]
|
|
|
|
|
|
S. R. Harris, D. Pisani, D. J. Gower, and M. Wilkinson Investigating Stagnation in Morphological Phylogenetics Using Consensus Data Syst Biol, February 1, 2007; 56(1): 125 - 129. [Full Text] [PDF]
|
|