A 7,000-pound T. rex fossil could rewrite century-old views of the dinosaur’s anatomy.

Paleontologist Paul Sereno and the Zerbst family uncovered “Rex Junior,” a partial but impeccably preserved sub-adult Tyrannosaurus rex skeleton on the Zerbst Ranch in eastern Wyoming. This discovery challenges long-standing assumptions about T. rex’s appearance and anatomy, offering a new structural understanding of the species.

Rex Junior was extracted intact from the Lance Formation, dating back 67 million years, and transported nearly 1,000 miles to the University of Chicago’s Fossil Lab for preparation and study. The specimen includes the only complete T. rex hand and forearm ever found, along with an articulated wishbone, features unseen in previous finds. Sereno notes the absence of scales, which may challenge prior reconstructions. The fossil appears mummified and three-dimensionally preserved, with Sereno suggesting it may have been buried alive during a flood. This find is associated with other dinosaur mummies found on the Zerbst Ranch, including “Lane,” a Triceratops specimen.

Further research on Rex Junior and other fossils from the “mummy zone” is expected to be published in early 2027.

The evolving picture of dinosaur integument and preservation might influence how researchers in Montana interpret their own finds and approach excavation techniques in similarly aged formations.

Found On Newcastle Ranch, ‘Rex Jr.’ Could Be Most Important T. Rex Ever Discovered
By @daily_cowboy, Cowboy State Daily

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Welcome to the Montana Dinosaur Trail!

This statewide trail runs across Montana and consists of 15 locations from the Montana Dinosaur Center in Bynum to the Carter County Museum in Ekalaka. Each location offers a glimpse at the historic discoveries in the state and provides visitors with a better understanding of the giants that once inhabited our planet.

Dinosaurs present the unknown – they ruled our planet for over 100 million years, and yet we know so little about them. Unlike lions, tigers and bears, we cannot simply drive down to the local zoo to study these massive creatures. Rather, we have to take a trip back in time and – piece by piece – put together their stories. It is our innate curiosity that has driven us to study these creatures. In Montana, we are privileged to host some of the richest dinosaur fossils, and the state boasts some of the most important discoveries and renowned paleontologists.

We have grown up with dinosaurs, seen the illustrations, visited the museums, and after a while, all of the remains (at least of the same species) begin to look relatively the same. The untrained eye may begin to question what we can learn from the 25th Triceratops specimen, but as Dr. John Scanella, the John R. Horner Curator of Paleontology at the Museum of the Rockies, once said, “just because something is old, or familiar, or common, that doesn’t mean that it has nothing left to teach us.”