The newly discovered tyrannosaurid species, scientifically named Khankhuulu Mongoliensis, is recognized as the most notable ancestor of Tyrannosaurus Rex.
Khankhuulu Mongoliensis roamed the Earth during the Cretaceous period approximately 86 million years ago.
This dinosaur was a medium-sized, swift predator that emerged after the extinction of other large predatory dinosaurs.
As the most famed ancestor, it exhibited numerous similarities with the later Tyrannosaurus descendants.
Resembling the size of a horse (750 kg), Khankhuulu Mongoliensis was two to three times smaller than its colossal descendants.
It featured small rudimentary horns that evolved into more significant attributes in species like Albertosaurus or Golgosaurus, likely used for mating displays and intimidation.
Characterized by a long, shallow skull, Khankhuulu Mongoliensis lacked the bone-crushing capabilities seen in Tyrannosaurus Rex.
This new species can be likened to mesopredators, similar to modern coyotes, utilizing speed and agility to capture prey.
“Khankhuulu Mongoliensis offers invaluable insights into the early stages of Tyrannosaurus evolution. We’ve observed numerous intriguing challenges in their evolutionary history,” remarked Jared Voris, a paleontologist at the University of Calgary.
Two partial skeletons of Khankhuulu Mongoliensis were discovered in the Baiansily Formation in southeastern Mongolia during 1972 and 1973.
Analysis of the specimens indicates that this new species is a close relative of the dinosaur group eutyrannosauria, serving as a direct ancestor to the giant, long-snouted tyrannosaurs and the shallower-nosed Ariolamini clade.
“Khankhuulu Mongoliensis or closely related species likely migrated from Asia to North America approximately 85 million years ago,” stated Dr. Darla Zelenitsky, Ph.D. from the University of Calgary.
“Our findings suggest that a large-scale tyrannosaur was the first to evolve in North America due to this immigration event.”
“The results indicate that the migratory patterns of tyrannosaurs between Asia and North America were less frequent and more erratic than previously understood.”
“Khankhuulu Mongoliensis or its relatives crossed the land bridge into North America, eventually evolving into the iconic apex predator, Tyrannosaurus Rex.
The fossil record indicates that Tyrannosaurus was exclusive to North America for millions of years before its lineage split in Asia, leading to two distinct groups.
One lineage evolved into larger apex predators, ultimately resulting in Tyrannosaurus Rex, while another developed into medium-sized, elongated species dubbed Pinocchiolex.
The discovery of Khankhuulu Mongoliensis is detailed in a study published in the journal Nature.
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JT Voris et al. The evolution of the new Mongolian tyrannosaur and Euthiranosaur. Nature published online on June 11th, 2025. doi:10.1038/s41586-025-08964-6
Source: www.sci.news
