3 days ago
Ancient T. rex ancestor discovered: Khankhuuluu, ‘prince of dragons'
A new species of early tyrannosaur, dubbed the 'prince of dragons,' has been discovered lurking in a collection of fossils first excavated in Mongolia in the early 1970s, scientists said Wednesday in the journal Nature.
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Khankhuuluu mongoliensis — its scientific name — is an evolutionary ancestor of the most famous tyrannosaur, the 'tyrant lizard king,' T. rex.
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With their bone-crushing bites and spindly little arms, large tyrannosaurs (scientifically known as 'eutyrannosaurians') are the celebrities of the dinosaur world. But they started off as small-bodied tyrannosauroids some 150 million years ago in the Jurassic period. It wasn't until the late Cretaceous that they began evolving into the giants that ignite people's imaginations.
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Their precise evolutionary origins, however, have long been murky. A critical swath of the family tree is blank.
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Khankhuuluu, known from two partial skeletons in fossil collections at the Institute of Paleontology in Mongolia, helps fill in this gap — a transitional 86 million-year-old species that represents the closest known ancestor to the famed late tyrannosaurs.
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Previously, it had been described as an alectrosaurus, another early tyrannosaur. Asked for a modern-day comparison, University of Calgary graduate student Jared Voris, who led the work, said to imagine a large, predatory horse.
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'What makes them so important is their age,' said Stephen Brusatte, a paleontologist at the University of Edinburgh who was not involved in the study. 'They are about 86 million years old, a good 20 million years older than T. rex. It has been a frustrating gap in the record.'
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Voris was on a research trip in Mongolia in 2023 when he sent a text halfway across the world to his adviser, Darla Zelenitsky, an associate professor of paleontology. He told her that he thought some of the fossils he had examined in a museum collection were actually a new species.
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Those specimens had been classified for decades as alectrosaurus, 'an enigmatic and poorly represented tyrannosauroid species,' Zelenitsky and Voris wrote in their study.
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What leaped out to Voris initially was that the snout bone was hollow, a clear sign that this was an early ancestor of the tyrannosaur family. It was the first of what would come to be dozens of features that suggested this creature was something new.
