Newly Discovered Dinosaur Is T. Rexs Awkward Cousin

Published: Wednesday, June 11, 2025 at 3:00 pm

**New Dinosaur Discovery Sheds Light on T. Rex Evolution**

A new study published today reveals the discovery of a previously unknown tyrannosauroid species, offering valuable insights into the evolution of the iconic Tyrannosaurus rex. The newly identified dinosaur, named Khankhuuluu mongoliensis, was unearthed from a geological formation in Mongolia.

Initially, the fossils were misidentified as belonging to a previously discovered species. However, a recent re-examination by an international team of researchers, led by paleontologists from the University of Calgary, led to the classification of the fossils as a new genus and species.

Khankhuuluu mongoliensis was a medium-sized predator, comparable in size to a grizzly bear. Its skull measured up to 27 inches long, and its femur was nearly 26 inches. This places Khankhuuluu in an evolutionary middle ground between the smaller, earlier tyrannosauroids and the colossal T. rex. The study suggests that Khankhuuluu branched off about 90 million years ago during the Late Cretaceous period, just outside the group that would eventually include the Eutyrannosaurians.

The discovery of Khankhuuluu provides crucial information about the evolutionary path of the Eutyrannosaurians, a group characterized by their enormous size, powerful jaws, short arms, and long legs. The study suggests that Khankhuuluu shares features with both the massive Tyrannosaurini and the smaller Alioramini clades. The new species also exhibits characteristics of juvenile Eutyrannosaurians, such as a slender build and longer forearms than legs, suggesting changes in developmental timing played a role in the evolution of these dinosaurs.

The research proposes that mid-sized dinosaurs like Khankhuuluu initially spread from Asia to North America, where they evolved into various Eutyrannosaurians, including T. rex. Later, tyrannosauroids migrated back to Asia, giving rise to other clades. Finally, Tyrannosaurini dispersed back to North America, evolving into the gigantic Tyrannosaurus species that dominated as apex predators until the end-Cretaceous mass extinction.

BNN's Perspective: This discovery is a fascinating glimpse into the evolutionary history of one of the most recognizable dinosaurs. While the details are complex, the findings highlight the dynamic nature of evolution and the importance of continued research in paleontology. The study underscores how much we still have to learn about the prehistoric world and the creatures that once roamed the Earth.

Keywords: dinosaur, Tyrannosaurus rex, T. rex, Khankhuuluu mongoliensis, tyrannosauroid, evolution, paleontology, fossils, Cretaceous period, Eutyrannosaurians, apex predator, Mongolia, new species, scientific discovery

Full Story