Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (27) Citing Articles via Google Scholar Google Scholar Articles by Carrano, M. T. Search for Related Content GeoRef GeoRef Citation

Homoplasy and the evolution of dinosaur locomotion

¹ Matthew T. Carrano. Department of Anatomical Sciences, Health Sciences Center T-8, State University of New York at Stony Brook, Stony Brook, New York 11794-8081. mcarrano{at}mail.som.sunysb.edu

In this paper, I survey hindlimb and pelvic anatomy across non-avian dinosaurs and analyze these within a cladistic framework to quantify patterns of change within the locomotor apparatus. Specifically, I attempt to identify where homoplasy constitutes parallelism and may thereby be used to infer similar selective pressures on hindlimb function. Traditional methods of discrete character optimization are used along with two methods for evaluating changes in continuous characters in a phylogenetic context (squared-change parsimony and clade rank correlation). Resultant patterns are evaluated in light of the biomechanics of locomotion and the relationship between form and function in extant terrestrial vertebrates.

Although non-avian dinosaurian locomotor morphology is strikingly uniform, these analyses reveal the repeated derivations of several morphological features that have potential relevance for hindlimb locomotor function. Anterior and posterior iliac expansion, a medially oriented femoral head, and an elevated femoral lesser trochanter each evolved independently multiple times within Dinosauria. These changes probably reflect enlargement of several hindlimb muscles as well as a general switch in their predominant function from abduction-adduction (characteristic of "sprawling" limb postures) to protraction-retraction (characteristic of parasagittal, or "erect," limb postures). Several "avian" characteristics are shared with more basal theropods, and many were acquired convergently in other dinosaurian lineages. The evolution of the avian hindlimb therefore represents a cumulative acquisition of characters, many of which were quite far removed in time and function from the origin of flight.

This article has been cited by other articles:

				A. J. Clark and A. P. Summers Morphology and kinematics of feeding in hagfish: possible functional advantages of jaws J. Exp. Biol., November 15, 2007; 210(22): 3897 - 3909. [Abstract] [Full Text] [PDF]

				F. R. O'Keefe and M. T. Carrano Correlated trends in the evolution of the plesiosaur locomotor system Paleobiology, December 1, 2005; 31(4): 656 - 675. [Abstract] [Full Text] [PDF]

				J. R. Hutchinson, F. C. Anderson, S. S. Blemker, and S. L. Delp Analysis of hindlimb muscle moment arms in Tyrannosaurus rex using a three-dimensional musculoskeletal computer model: implications for stance, gait, and speed Paleobiology, December 1, 2005; 31(4): 676 - 701. [Abstract] [Full Text] [PDF]

				J. A. Wilson Integrating ichnofossil and body fossil records to estimate locomotor posture and spatiotemporal distribution of early sauropod dinosaurs: a stratocladistic approach Paleobiology, September 1, 2005; 31(3): 400 - 423. [Abstract] [Full Text] [PDF]

				R. R. Reisz, D. Scott, H.-D. Sues, D. C. Evans, and M. A. Raath Embryos of an Early Jurassic Prosauropod Dinosaur and Their Evolutionary Significance Science, July 29, 2005; 309(5735): 761 - 764. [Abstract] [Full Text] [PDF]

				Adductors, abductors, and the evolution of archosaur locomotion Paleobiology, December 1, 2000; 26(4): 734 - 751.