Geek研究: 恐龍Sue是雄性的嗎？

Larson set out to determine the sex of his fossil. First, he dissected a series of modern crocodiles. Male crocodiles, like many reptiles, have a penis-like sex organ that can be extended or retracted into the body. The muscles that control this movement are attached to the first of several bony protuberances, called chevrons, that extend from the underside of the tail vertebrae. In the male crocodiles that Larson examined, the chevrons were all of equal length. In the female crocodiles, however, the first chevron–where the penis muscles normally attach–was noticeably shorter than the rest. Next, Larson examined fourteen T. rex skeletons. The dinosaur skeletons showed a pattern similar to that of the modern crocodiles. Some had a shortened first chevron, located farther down the tail, while some had chevrons of equal length. Larson concluded that the dinosaurs with shorter chevrons were probably females. In addition, the skeletons with smaller chevrons were more massive, an overall size pattern that coincides with earlier observations that female dinosaurs were bigger than males, like many modern reptiles and birds of prey.