Paleontologists examining neglected specimens in museum drawers have identified the first known fossils of Tyrannosaurus rex hatchlings. Published in the journal Biology, the study shows these young dinosaurs measured roughly 75 centimeters long and weighed about 2.5 kilograms, comparable to a domestic cat and smaller than earlier estimates.
The bones display porous surfaces indicating rapid early growth through dense networks of blood vessels. Researchers determined the remains belonged to hatchling tyrannosaurs rather than embryos or the pygmy species Nanotyrannus, based on distinctive foot bone and tooth features that match those of adult T. rex.
The discovery suggests hatchlings emerged from eggs even smaller than previously calculated, possibly as light as 1.7 kilograms. It also indicates that young tyrannosaurs already possessed robust teeth capable of crushing bone, similar to much larger adults.
The findings emerged after scientists reviewed fragmented fossils long overlooked in favor of bigger skeletons. The work underscores how small isolated bones can yield significant insights when reexamined with modern techniques.
