KU paleontologist David Burnham resumes final excavation of the juvenile tyrannosaur

LAWRENCE – A team of paleontologists from the University of Kansas is back in Montana this summer for the final excavation of a rare dinosaur fossil: a juvenile tyrannosaur.

David Burnham, preparator of vertebrate paleontology at the KU Biodiversity Institute and Natural History Museum, is leading the four-week expedition in search of fossil remains belonging to the tyrannosaur. Burnham and his team of students and volunteers first discovered the specimen in 2016 and returned to the dig site the second week of July as a final effort to finish the excavation. 

The research team will again systematically search the site, which is in the Hell Creek Formation, to ensure it has not overlooked anything. Additional fossils will provide meaningful insights into the specimen’s prehistoric past and contribute to understanding of the species’ evolutionary history.

The discovery of a juvenile tyrannosaur fossil is extremely rare. Of the approximately 100 T. rex fossils discovered so far, only a handful are juveniles. But what makes this KU specimen an even greater rarity is the exquisite preservation of its teeth, according to researchers. The KU tyrannosaur has all its teeth intact in the upper jaw, along with its respective replacement teeth. One of the more remarkable differences between young and adult tyrannosaurs are their teeth. The young tyrannosaur has less robust, more blade-like teeth than an adult, possibly reflecting differences in their feeding ecology. 

Burnham and his students published a preliminary report in 2018 based on the tooth study.

"The young tyrannosaur probably had not yet reached its teen years and did not have the same powerful bite as an adult," Burnham said. "The KU specimen provides ample evidence indicating the hard life young tyrants endured growing up under the shadow of adult T. rex was difficult and may have required help from cohorts while hunting."

A complete skeleton of the tyrannosaur would be around 25 feet long with a 3-foot-long skull and was not large enough to take down massive prey items like the adults. Burnham and his team will publish their findings about the tyrannosaur later this year, hopefully unraveling its enigmatic evolutionary relationships. 

The fossil was excavated by KU field crews working under a permit, 2024-00645, from the Bureau of Land Management, Eastern Montana/Dakotas District. Burnham and his team expressed thanks to the Bureau of Land Management for its service with this excavation and the many others that have taken place.