Mary Higby Schweitzer, Wenxia Zheng, Lindsay Zanno, Sarah Werning & Toshie Sugiyama (2016)
Chemistry supports the identification of gender-specific reproductive tissue in Tyrannosaurus rex.
Scientific Reports 6, Article number: 23099 (2016)
Medullary bone (MB), an estrogen-dependent reproductive tissue present in extant gravid birds, is texturally, histologically and compositionally distinct from other bone types. Phylogenetic proximity led to the proposal that MB would be present in non-avian dinosaurs, and recent studies have used microscopic, morphological, and regional homologies to identify this reproductive tissue in both theropod and ornithischian dinosaurs. Here, we capitalize on the unique chemical and histological fingerprint of MB in birds to characterize, at the molecular level, MB in the non-avian theropod Tyrannosaurus rex (MOR 1125), and show that the retention of original molecular components in fossils allows deeper physiological and evolutionary questions to be addressed.