Tiny T-rex fossil found
Experts have unearthed a tiny fossil which is the T-rex's oldest known relative.
The find suggests the T-rex was very small before it evolved into a giant killing machine.
The fossil has a similar skull and the same banana-shaped teeth as the modern T-rex.
The skull also has big windows for more muscles.
The fossil was found in Gloucestershire. It had a tiny horn on its nose. The dinosaur lived 170 million years ago. T-rex ruled the earth about 85 million years to 65 million years ago.