A newly identified dinosaur species in Mongolia, Khankhuuluu mongoliensis, is now considered the closest-known ancestor to T. rex, reshaping tyrannosaur evolution.
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| The discovery of Khankhuuluu mongoliensis in Mongolia offers the most direct evolutionary link to T. rex, unlocking new understanding of tyrannosaur development. Image Courtesy: Anthony Hutchings/University of Southampton/ CNN |
Ulaanbaatar, Mongolia — June 12, 2025:
In a breakthrough for dinosaur science, researchers have identified a new species of tyrannosaur ancestor in Mongolia that significantly alters our understanding of how Tyrannosaurus rex evolved. Named Khankhuuluu mongoliensis, or “Dragon Prince of Mongolia,” the species was described in a new study published in Nature, based on fossils found in the 1970s but only recently reclassified.
The fossilized remains, dated to 86 million years ago, were initially thought to belong to an existing species, Alectrosaurus. But upon closer inspection, PhD student Jared Voris and his team at the University of Calgary found key anatomical differences—especially in the nasal and jawbones—suggesting this was a transitional form in the tyrannosaur lineage.
“This discovery rewrites what we know about the origins of T. rex,” said Prof. Darla Zelenitsky, co-author of the study. “Khankhuuluu bridges the evolutionary gap between smaller, fleet-footed predators and the massive apex hunters that roamed North America and Asia.”
Weighing around 750 kilograms—about one-eighth the size of an adult T. rex—Khankhuuluu displayed early adaptations such as robust skull structure and powerful jaws, traits that would later define the tyrannosaur dynasty. These features allowed later species to crush bone and prey on much larger animals.
The discovery also reveals how land bridges between Asia and North America allowed species migration, influencing tyrannosaur diversification across continents. "This back-and-forth movement drove evolutionary change in these predators," said Voris.
Beyond its evolutionary significance, the finding underscores the importance of revisiting historic fossil collections with new tools and perspectives. “Before tyrannosaurs ruled as kings,” said Zelenitsky, “they were evolving as princes, honing the traits that would define their dominance.”
The research offers a fresh look at the tyrannosaur family tree and strengthens Mongolia's role as a vital region for understanding dinosaur evolution.