Scientists have identified a new dinosaur from fossils dug up in China and nicknamed it T-rex's cousin.
The gigantic creature roamed North America and east Asia between about 65 million and 99 million years ago.
Researchers led by Dr David Hone, from University College Dublin (UCD), discovered fragments of fossils from the meat eater in a so-called dinosaur quarry in the eastern Chinese province of Shandong.
Known as a theropod because it walks on its two hind legs, the dinosaur is said to be a close relative of T-rex, according to the research published in Cretaceous Research in the online journal Science Direct.
It was identified from skull, jaw bone and pieces of teeth. Based on their size it measured about 11m long, stood about 4m tall and weighed close to six tonnes. It had a 1m-long skull and rounded, chisel-like, bone-crushing teeth 9cm long.
Dr Hone, from UCD's school of biology and environmental science, spent three years at the Shandong site before joining the Dublin college.
"It's another big T-rex and these things don't turn up every day. It's one of the biggest predators of all time," he said.
"It's the first super-gigantic T-rex relative discovered in quite a long time. It would be top of the food chain because it would be the biggest thing out there feeding but there are a couple of others out there the same size."
The dinosaur has been officially named Zhuchengtyrannus magnus - Tyrant from Zhucheng - in honour of Zhucheng, the city in which the fossils were found. But because of its huge size, scientists quickly tagged it T-rex's cousin.
Dr Hone said: "With only some skull and jaw bones to work with, it is difficult to precisely gauge the overall size of this animal. But the bones we have are just a few centimetres smaller than the equivalent ones in the largest T-rex specimen. So there is no doubt that Zhuchengtyrannus was a huge tyrannosaurine."