Tyrannosaurus rex cub could be an embryo
Tyrannosaurus rex cub could be an embryo

Tyrannosaurus Cub found: skull fossils say it was the size of a mouse

Tyrannosaurus rex cub could be an embryo

The first of its kind fossils of a baby Tyrannosaurus rex was studied by the scientists. They suggest that the remains could even belong to an embryo. The skull of a giant animal at that age was the size of a mouse skull. Such a conclusion was made after analyzing the found claw on the paw of a baby tyrannosaurus, the remains of which were found in Canada in 2017. It prompted the researchers to study the jawbone of a Tyrannosaurus rex, that was previously found in Montana in 1983, in detail.

The researchers consider these findings incredible and very different. According to the lead researcher Gregory Funston, a paleontologist at the University of Edinburgh in Scotland, the discovery of such remains is rare. Until now, no bones have been found to confirm their belonging to the embryos.


The cub's jaw measures about 2.9 centimeters. It has 8 small teeth. Part of the body is tightly preserved in the rock, and the study was carried out using a particle accelerator, which made it possible to obtain an image of the fossilized remains without removing it from the rock. Despite the diminutive size of the jawbone, it is similar to the jaws of other young tyrannosaurs.

The similarity is confirmed by a deep groove and a distinctly pronounced chin, such features are inherent only in predatory tyrannosaurs. The cranial reconstruction suggests that the embryonic development of the Tyrannosaurus rex skull did not exceed the size of the modern mouse skull.

The images show that the jawbone was not fully developed, as were the teeth. By the way, one of the teeth also confirms the attitude towards the embryonic state of the Tyrannosaurus. It means that the baby of a giant prehistoric animal died without hatching.


In one of the sockets of the teeth, a replacement tooth was found, located in a strange way. Lacking evidence of root decay, it is a so-called milk process, which is also inherent only in the embryo. Further studies of the remains of an ancient animal will help the scientists to obtain new data on the evolution of tyrannosaurs.