Tyrannosaurus rex holotype specimen at the Carnegie Museum of Natural History, Pittsburgh. Credit: Scott Robert Anselmo

U.S. paleontologists have been able to establish the gender of a Tyrannosaurus Rex on a molecular level based on a certain bone.

Medullary bone

This bone is called a medullary bone and not so surprising it can be found among female birds today. The medullary bone is rich in calcium, providing female birds with a ready source of material for making hard eggshells.

Finding this bone in a T. Rex fossil implies that this dinosaur must have been an egg layer, too. It has long been suspected that the bone should exist in dinosaur fossils, but this is the first time scientists have been able to prove it.

Birds and Dinosaurs

This enables a method to determine if a dinosaur fossil is a female or a male. This has been impossible until now. Scientists can now make more specific conclusions of how the different sexes differed.

It also opens the door for further research on when and why this bone appeared, and clearly shows how closely related birds and dinosaurs are.

Chemistry supports the identification of gender-specific reproductive tissue in Tyrannosaurus rex