HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by GATES, T. A. Search for Related Content GeoRef GeoRef Citation

The Late Jurassic Cleveland-Lloyd Dinosaur Quarry as a Drought-Induced Assemblage

¹ Department of Geology and Geophysics, University of Utah, Utah Museum of Natural History, 1390 E Presidents Circle, Salt Lake City, UT 84112; tgates{at}umnh.utah.edu

ABSTRACT

A comprehensive taphonomic analysis has yielded a novel interpretation for one of the most famous dinosaur quarries in the world. The Cleveland-Lloyd Dinosaur Quarry (CLDQ) traditionally has been interpreted as an attritional predator trap. This scenario is based largely on a remarkable 3:1 predator:prey ratio, dominated by the remains of the theropod Allosaurus fragilis. This study addresses the taphonomy of CLDQ by combining analyses of fossils and entombing sediments along with putative modern analogues.

Thousands of bones have been excavated from CLDQ, representing at least 70 individual dinosaurs from a minimum of nine genera. The fossils occur in a 1-m-thick fine-grained calcareous mudstone interpreted as a floodplain ephemeral-pond deposit. The bones show minimal carnivore modification and surface weathering, whereas approximately 1/3 of the elements studied possess pre-depositional fractures and evidence of abrasion. The vast majority of elements are found horizontal to subhorizontal, without a preferred long-axis orientation. The demographic profile of the CLDQ dinosaur assemblage appears to be highly skewed toward subadult individuals.

Numerous lines of evidence question the traditional predator-trap hypothesis. Of the alternatives, catastrophic drought appears to be most consistent with available data. Evidence includes a large assemblage of animals in a low-energy ephemeral-pond depositional setting and geologic and biologic evidence of desiccation. Additional support comes from modern drought analogues that frequently result in mass-death assemblages of large vertebrates. Climatic interpretations during Late Jurassic times are consistent with a semiarid environment characterized by periodic drought conditions.

This article has been cited by other articles:

				D. A. EBERTH, X. XING, and J. M. CLARK DINOSAUR DEATH PITS FROM THE JURASSIC OF CHINA Palaios, February 1, 2010; 25(2): 112 - 125. [Abstract] [Full Text] [PDF]

				P. Lauters, Y. L. Bolotsky, J. Van Itterbeeck, and P. Godefroit Taphonomy and Age Profile of a Latest Cretaceous Dinosaur Bone Bed in Far Eastern Russia Palaios, March 1, 2008; 23(3): 153 - 162. [Abstract] [Full Text] [PDF]

				C. A. SUAREZ, M. B. SUAREZ, D. O. TERRY JR., and D. E. GRANDSTAFF RARE EARTH ELEMENT GEOCHEMISTRY AND TAPHONOMY OF THE EARLY CRETACEOUS CRYSTAL GEYSER DINOSAUR QUARRY, EAST-CENTRAL UTAH Palaios, September 1, 2007; 22(5): 500 - 512. [Abstract] [Full Text] [PDF]

				M. B. SUAREZ, C. A. SUAREZ, J. I. KIRKLAND, L. A. GONZALEZ, D. E. GRANDSTAFF, and D. O. TERRY JR. SEDIMENTOLOGY, STRATIGRAPHY, AND DEPOSITIONAL ENVIRONMENT OF THE CRYSTAL GEYSER DINOSAUR QUARRY, EAST-CENTRAL UTAH Palaios, September 1, 2007; 22(5): 513 - 527. [Abstract] [Full Text] [PDF]