A slender predator named Khankhuuluu mongoliensis may be the closest known ancestor to T. rex — and it could outrun you.
Tyrannosaur fans, meet the dragon that came before the king.
Scientists have just confirmed the most recent — and most revealing — ancestor of the tyrannosaur family: Khankhuuluu mongoliensis, a mid-sized, hyper-agile predator that walked the Earth 86 million years ago. And unlike the lumbering T. rex, this one would have chased you down and eaten you.
Identified from partial skeletons found in the Gobi Desert and long misclassified as Alectrosaurus olseni, the fossils were re-analyzed by paleontologists from the University of Calgary and Mongolian Academy of Sciences. The new species was unveiled this week in Nature, with researchers calling it a missing evolutionary link between small, early tyrannosaurs and their later giant cousins.
“It’s basically the prototype for the entire T. rex bloodline,” said Dr. Darla Zelenitsky, study co-author.
At roughly 4 meters long and 750 kg, Khankhuuluu wasn’t quite the apex monster T. rex became — but it had speed, serrated teeth, and a build optimized for ambush. It’s now considered the last known direct precursor before the tyrannosaur lineage exploded in size.
Tyrannosaur Evolution Was Shaped by Cross-Continent Migrations
Using advanced computational models, researchers traced the global journey of tyrannosaurs. Here’s what they found:
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Asia birthed the Khankhuuluu-like ancestors
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These species migrated into North America, eventually producing T. rex
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Later tyrannosaurs like Tarbosaurus and Alioramus (the so-called “Pinocchio rex”) evolved after some species moved back into Asia
The new timeline corrects previous assumptions that tyrannosaur migration was frequent and chaotic — instead, it happened in major pulses, tightly tied to geography and climate.
“The entire T. rex story is one of strategic relocation,” said lead author Jared Voris.
Why This Discovery Matters Now
For dino hunters, evolutionary biologists, and anyone tracking key fossil finds of 2025, Khankhuuluu is a game-changer:
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Fills a major fossil gap in the tyrannosaur lineage
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Validates predictive models for missing dinosaur ancestors
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Links species migrations to evolutionary scale-ups
As Prof. Steve Brusatte (University of Edinburgh) notes: “It’s proof that size didn’t come first. Speed, shape, and location did.”
