Initially, Dalman was studying a large bone that had been in the Science Museum’s collection since the 1930’s. That bone, found by Amherst College professor Frederick Loomis in 1924, turned out to be a humerus or upper front leg bone from a sauropod dinosaur called Alamosaurus sanjuanensis, the largest dinosaur ever to live in North America. It was found in New Mexico’s Ojo Alamo Formation, which dates the bone back to the Late Cretaceous era, roughly 68 million years ago.

While preparing the Alamosaurus bone for display, Dalman and museum staff decided to also exhibit another Cretaceous-era fossil, a pubis bone thought to have been from Tyrannosaurus rex. This second bone, also collected by Professor Loomis, had notations indicating that it came from Hell Creek, Montana, an area famous for yielding T. rex fossils.

Working with Dr. Spencer Lucas, Dalman determined that the pubis bone was actually found by Loomis at the same Ojo Alamo Formation site in New Mexico that yielded the  Alamosaurus fossil. Evidently, one of Loomis’ students had improperly marked “Hell Creek” as the source of the pubis bone when it first arrived at Amherst College in the 1920’s.

After subjecting the pubis bone to further scrutiny, Dalman and Lucas were able to determine that the bone actually came from an entirely new tyrannosaurid species, a slightly smaller cousin of the famous T. rex. The two researchers had already been studying another fossil at the Beneski Museum, a jawbone also found by Loomis at the Ojo Formation site, and ultimately determined that it, too, came from this same new species of tyrannosaur.

Yet there was still one more secret waiting to be uncovered. In the course of his research, Dalman also noted deep grooves in the Science Museum’s Alamosaurus bone that appeared to be bite marks made by a large predator. On a hunch, he compared the bite marks to teeth from the Beneski Museum’s jawbone and determined that that the marks were most likely made by a member of this new tyrannosaur species. If so, the bite marks provide the first evidence in North America that tyrannosaurs fed on Alamosaurus.

What these discoveries mean for tyrannosaur evolution and distribution remains to be seen. Dalman is currently in the process of submitting his findings for academic review. If the findings are proven correct, the new species will then be given a proper scientific name.

In the meantime, the pubis bone from the still-unnamed tyrannosaur is part of a new display in Dinosaur Hall at the Springfield Science Museum, alongside the larger Alamosaurus bone and photos from Professor Loomis’ expeditions.

“We’re all intrigued by this discovery, and extremely excited to see how this all turns out,” commented David J. Stier, Director of the Springfield Science Museum, adding “We’re indebted to our colleagues at the Beneski Museum and at the Perot Museum of Nature and Science in Dallas, Texas for their assistance with this effort.”