The T-rex, which was found in Montana and dates back 68 million years, retained medullary bone revealing the individual was pregnant. Medullary bone is only present in female birds — which are related to dinosaurs — just before and during egg-laying. It is this type of bone that could retain preserved DNA. This discovery will shed light on the evolution of egg-laying as well as on gender differences in the dinosaur. http://www.abc.net.au/news/2016-03-...heds-light-on-evolution-of-egg-laying/7251466
