London, April 22 : A fossil found in China, dating from the middle of the Cretaceous period, may belong to a dinosaur that was probably the ancestor of the Tyrannosaurus Rex.

According to a report by BBC News, uncovered near the city of Jiayuguan, the fossil finds come from a novel tyrannosaur dubbed Xiongguanlong baimoensis.

The fossils date from the middle of the Cretaceous period, and may be a “missing link”, tying the familiar big T rex to its much smaller ancestors.

The fossils show early signs of the features that became pronounced with later tyrannosaurs.

Paleontological knowledge about the family of dinosaurs known as tyrannosaurs is based around two distinct groups of fossils from different parts of the Cretaceous period, which ran from approximately 145 to 65 million years ago.

One group dates from an early part of the period, the Barremian, and the other is from tens of millions of years later.

Before now, it has been hard for palaeontologists to trace the lineage from one group to the other.

“We’ve got a 40-50 million year gap in which we have very little fossil record,” said Peter Makovicky, associate curator at the Field Museum in Chicago, who helped to lead the US/Chinese team that uncovered the fossil.

But, he said, X baimoensis was a “nice link” between those two groups.

Dr Makovicky and colleagues suggest that X baimoensis is a “phylogenetic, morphological, and temporal link” between the two distinct groups of tyrannosaurs.

The fossil has some hallmarks of large tyrannosaurs such as a boxy skull, reinforced temple bones to support large jaw muscles, modified front nipping teeth and a stronger spine to support a large head.

But, it also shows features absent from older tyrannosaurs, such as a long thin snout.

An adult would have stood about 1.5m tall at the hip and weighed about 270kg. By contrast, an adult T rex was about 4m tall at the hip and weighed more than 5 tonnes. (ANI)