T-Rex had secret cousin with blunter teeth, scientists find
The T-Rex had a previously unknown cousin with blunter teeth and a weaker bite, scientists have found.
Few animals are as famous as the Tyrannosaurus rex, which was the apex predator before all dinosaurs were wiped out by a meteorite 65 million years ago.
Its skeleton, teeth and anatomy is known in such minute detail that when scientists reanalysed a specimen found 40 years ago in New Mexico they identified subtle changes to its skull, jaw and teeth, which further analysis revealed the animal was actually a different species.
The animal has been dubbed Tyrannosaurus mcraensis and grew to the same size as a T-Rex, about 12-metres (40ft) and weighing ten tons, and was roughly the same in proportions.
However, the sister species is thought to have existed before the T-Rex and lived around seven million years earlier.
Scientists said the T-Rex was more fearsome as it was a highly tuned killing machine and last of the tyrannosaurid genus.
Dr Nick Longrich, study co-author and palaeontologist from the University of Bath, said: “The shape of the lower jaw is distinct.”
“The chin is less prominent and the back of the jaw is slender, where it’s much deeper in T-Rex. T-Rex probably had a stronger bite as a result of the deeper mandible.”
He added that the teeth are also different between the two sister tyrannosaurus species with the T-Rex’s “like railroad spikes” or fangs compared with the blunter, more blade-like dentition of the new species.
“It’s more primitive and not quite as specialised. It is big but doesn’t have the same degree of specialisation to crush and pierce bone that you get in T-Rex,” he added.
The scientists said the two species are not descendants or ancestral, but cousin species that were branches of the same chain.
“The differences are subtle, but that’s typically the case in closely related species,” Dr Longrich added.
“Evolution slowly causes mutations to build up over millions of years, causing species to look subtly different over time.”
The study is published in the journal Scientific Reports.