Researchers May Have Unearthed A Baby Tyrannosaur Fossil In Montana

Dinosaur fossil investigation could help unravel the life history of Tyrannosaurus rex

Paleontologists have unearthed a new fossil in Montana' Hell Creek Formation and they believe that the specimen belongs to a young Tyrannosaurus rex dinosaur.

The fossil consists of a complete section of the upper jaw with all of its teeth intact, along with partial skull, foot, hips, and backbones and is estimated to be 66.5 million years old. However, researchers are uncertain whether it is actually a T. rex or another species of smaller meat-eating dinosaur. Some even suggest that all previously found fossils in Montana which were thought to belong to a different species were, in fact, the same and represent different growth stages of Tyrannosaurus rex. Further analysis is underway to eliminate this uncertainty.

“The teeth suggest that it’s a Tyrannosaurus rex; however, there is still more work to be done,” said David Burnham, a vertebrate paleontologist from University of Kansas. “Because a young T. rex is so rare, there are only a few that have been found over the years, so it’s difficult to discern what are changes due to growth or if the differences in the bones reflect different species. Fortunately, KU has an older T. rex to compare with and another young T. rex on loan to help decipher this problem.”

One possibility is that the specimen is a Nanotyrannus dinosaur whose identity itself is a subject of controversy. Nanotyrannus is either a separate carnivorous dinosaur species or a kind of relative of the mighty Tyrannosaurus rex. One such specimen was reportedly discovered in Hell Creek Formation before.

“Confusing the issue here is age,” said Burnham. “Ontogeny, that's the process of growth—and during that process, we change. Adult dinosaur bones, especially in the skull, don’t look the same as their younger selves. So, if someone finds a baby or juvenile fossil they may think it’s a new species, but we have to be careful since it may represent a younger growth stage of an existing species. It’s reasonable to assume Nanotyrannus could be valid – but we must show it’s not just a stage in the life history of T. rex.”

While researchers are currently investigating the newfound fossil, they are also planning to visit Hell Creek Formation and to conduct a fieldwork in search of more bones. With more fossil record and examination, they are hoping to put an end to this controversy and aiming to give the fossil its rightful place in the family tree of theropod dinosaurs.

“We are going to go back out this summer – we’re going right to that spot. We think and hope there’s more there,” said Burnham. “With the specimens here at KU, we’ll be able to address the issue and make a declarative statement about Nanotyrannus.”

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