Talk about a rough day for a young dinosaur.

An adolescent tyrannosaurus found in far southeastern Montana had its face badly bitten, probably by a fellow young dinosaur, according to a new study.

Joe Peterson, a paleontologist at Northern Illinois University, said the snout and upper jaw of the Tyrannosaurus rex have deep puncture wounds consistent with the flesh-tearing teeth of another T. rex. Researchers theorize the scrap may have been over a show of dominance or a territorial dispute.

The young T. rex survived the attack but was left less than pretty.

"We were kind of joking, calling it a boxer's nose because it was a little bit crooked," Peterson said.

The dinosaur lived some 66 million years ago when the area was part of a lush floodplain. The fossil was found in 2001 in Carter County and excavated the next year. The 21-foot skeleton, nicknamed Jane, is now a popular display at the Burpee Museum of Natural History in Rockford, Ill.

For years after the discovery, scientists debated the dinosaur's age and type. While the debate roiled, scientists paid little attention to the four lesions on the skull.

"But it dawned on us that this might be important," Peterson said.

A closure look showed the oblong punctures resembled the shape of Jane's teeth.

"Since she can't bite herself, we thought it must've been something very similar to her," Peterson said.

Jane was named after one of the museum's donors and, although researchers don't know its gender, they refer to it as a female because of the name.

The dinosaur hadn't reached maturity by the time it died at 11 or 12 years old, the researchers said, which likely means the bites didn't come during some kind of sexual conflict. That's why they speculate it came during some kind of tussle over dominance or territory.

"What's unique about this work is we learn something very, very specific about juvenile dinosaur behavior," NIU professor Reed Scherer, who also worked on the study, said in a statement. "This was an animal about the same size that attacked Jane. Whether it was a sibling or from a rival group, we don't know, but it's fun to speculate."

Peterson said similar face-biting behavior has been seen on other adolescent animals, including crocodiles, modern ancestors of dinosaurs.

A recent study suggested that apparent bite marks in some dinosaurs were actually skull holes produced by a parasite. Peterson said they don't think that's the case with Jane.

The study results are published in the latest edition of the journal Palaios.

Jack Horner, a dinosaur expert at the Museum of the Rockies in Bozeman who was not involved in the study of Jane, said the conclusions are within the realm of possibility. Whether they were predators or scavengers, T. rexes likely fought over carcasses in the same way modern carnivores do, he said.