Archaeologists in northeast Montana have uncovered fossils that may link to ancestors of the mighty Tyrannosaurus rex (T. rex).
Fossils of Daspletosaurus wilsoni, the speculated ancestor of the T. rex, were found in Valley County, Montana. In 2017. Jack Wilson, a crew member at the Badlands Dinosaur Museum, noticed a small bone protruding from a cliff in the Judith River Formation. Between then and 2021, multiple fossils were found.
Torosus, the first species of the Daspletosaurus genus was uncovered by Charles M. Sternberg, a Canadian paleontologist, in 1921. Sternberg originally classified the fossils as a species of Gorgosaurus, a smaller tyrannosaurid dinosaur whose fossils were also found in Alberta, Canada. But it wasn’t until 1970 when fellow Canadian paleontologist, Dale Russell, classified the fossils under Daspletosaurus, which had a heavier build and larger body.
The discovery of these fossils offered the possibility that Daspletosaurus is an older relative of the T. rex through a form of gradual evolution known as anagenesis. Anagenesis, or linear evolution, is when a species directly evolves from another instead of branching off and producing different species. At first, many dinosaurs were considered to have evolved from cladogenesis or nonlinear evolution. However, more species have shown evidence of linear evolution. In the case of D. wilsoni, the dinosaurs’ fossils have features from older T. rexes as well as features that would appear in younger relatives. This makes D. Wilsoni a candidate for being an older cousin of the T. rex.
Investigations regarding the history of the dinosaur require scientists to cut and remove fossils. Archaeologists hope to learn more about this ferocious creature in the upcoming years.
[Source: Badlands Dinosaur Museum; Associated Press; sciencetimes.com]