How to tell if a T. rex is expecting

Chemical test of fossil detects a kind of estrogen-fueled bone that’s also found in egg-producing female birds

T. rex and bone

IT’S A GIRL  New chemical analyses can reveal whether a T. rex was “pregnant,” and thus female, by detecting the presence of loosely woven “medullary bone” (light colored material in inset picture) inside a fossilized bone.

Sofia Santos/Shutterstock, inset: M. Schweitzer et al/Scientific Reports 2016

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