Gender-Specific Reproductive Tissue in Ratites and Tyrannosaurus rex

Published on Jun 3, 2005in Science41.063
· DOI :10.1126/science.1112158
Mary H. Schweitzer28
Estimated H-index: 28
Jennifer L. Wittmeyer6
Estimated H-index: 6
John R. Horner44
Estimated H-index: 44
Unambiguous indicators of gender in dinosaurs are usually lost during fossilization, along with other aspects of soft tissue anatomy. We report the presence of endosteally derived bone tissues lining the interior marrow cavities of portions of Tyrannosaurus rex (Museum of the Rockies specimen number 1125) hindlimb elements, and we hypothesize that these tissues are homologous to specialized avian tissues known as medullary bone. Because medullary bone is unique to female birds, its discovery in extinct dinosaurs solidifies the link between dinosaurs and birds, suggests similar reproductive strategies, and provides an objective means of gender differentiation in dinosaurs.
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