New York, Oct 30 (IANS): A recently unearthed tyrannosaur bone has revealed a nasty little 66-million-year-old family secret that T.Rex were not shy about eating their own kind, say researchers.

The bone has peculiar teeth marks that strongly suggest it was gnawed by another tyrannosaur.

"We were out in Wyoming digging up dinosaurs in the Lance Formation," said paleontologist Matthew McLain from Loma Linda University in California, US.

"Someone found a tyrannosaur bone that was broken at both ends. It was covered in grooves. They were very deep grooves," McLain said.

The grooves were clearly those of an animal pulling the flesh off the bone.

The researchers found that one groove was located at the larger end of the bone and contained smaller parallel grooves caused by the diner's head turning, so that the serrated edges of its teeth dragged across the bone.

Serrated teeth rule out crocodiles and point directly to a theropod dinosaur like T. rex.

The fact that the only large theropods found in the Lance Formation are two tyrannosaurs --Tyrannosaurus rex or Nanotyrannus lancensis -- eliminates all interpretations but cannibalism, McLain explained.

"This has to be a tyrannosaur," McLain.

"There is just nothing else that has such big teeth," McLain noted.

However, the bones do not reveal whether the cannibal was scavenging or was also the killer of the tyrannosaur, the researchers said.

The findings will be presented on the opening day of the annual meeting of the Geological Society of America to be held in Baltimore, Maryland from November 1-4.