Dinosaur fossils found in China have got scientists pretty excited as they say they'll help them learn loads more about the ferocious Tyrannosaurus Rex.
Found near the city of Jiayuguan, the remains are from a type of tyrannosaur being called Xiongguanlong baimoensis.
The name may be a bit of a mouthful, but it's thought the fossils could provide the missing link between the huge T Rex and its smaller ancestors.
They date from part of the Cretaceous period - about 100 million years ago.
Scientists say the fossils show early signs of features that became more pronounced with later tyrannosaurs, like a boxy skull and stronger spine to support a large head.
Fill the gaps
The family of tyrannosaur dinosaurs are known to be based around two groups of fossils from different parts of the Cretaceous period.
One group dates from the early part - about 145 million years ago - and the other is from tens of millions of years later.
Until now, it's been hard for experts to fill in the gaps and trace the links between those groups.
But expert Peter Makovicky, who helped lead the team that unearthed the fossils, said their discovery was changing all that.
"We're filling in that part of the fossil record," he said.