title: A possible instance of sexual dimorphism in the tails of two oviraptorosaur dinosaurs.
abstract: The hypothesis that oviraptorosaurs used tail-feather displays in courtship behavior previously predicted that oviraptorosaurs would be found to display sexually dimorphic caudal osteology. MPC-D 100/1002 and MPC-D 100/1127 are two specimens of the oviraptorosaur Khaan mckennai. Although similar in absolute size and in virtually all other anatomical details, the anterior haemal spines of MPC-D 100/1002 exceed those of MPC-D 100/1127 in ventral depth and develop a hitherto unreported "spearhead" shape. This dissimilarity cannot be readily explained as pathologic and is too extreme to be reasonably attributed to the amount of individual variation expected among con-specifics. Instead, this discrepancy in haemal spine morphology may be attributable to sexual dimorphism. The haemal spine form of MPC-D 100/1002 offers greater surface area for caudal muscle insertions. On this basis, MPC-D 100/1002 is regarded as most probably male, and MPC-D 100/1127 is regarded as most probably female.
authors.affiliation: University of Alberta, Department of Biological Sciences, Edmonton, Alberta, T6G2E9, Canada.
authors.forename: W Scott
authors.initials: WS
authors.lastname: Persons
authors.affiliation: University of Alberta, Department of Biological Sciences, Edmonton, Alberta, T6G2E9, Canada.
authors.forename: Gregory F
authors.initials: GF
authors.lastname: Funston
authors.affiliation: University of Alberta, Department of Biological Sciences, Edmonton, Alberta, T6G2E9, Canada.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Currie
authors.affiliation: American Museum of Natural History, New York City, New York, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Norell
mesh_terms: D000818:Animals; D025061:Dinosaurs / Q000033:anatomy & histology*; D005260:Female; D008297:Male; D012727:Sex Characteristics; D013131:Spine / Q000033:anatomy & histology; D013623:Tail / Q000033:anatomy & histology*
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