A newly discovered T. rex relative! Khankhuuluu mongoliensis

I loved dinosaurs and new discoveries are always fascinating. The latest is from Mongolia and it's a relative to the Tyrannosaurus Rex. That's today's blog.

(Image: An artist impression of Khankhuuluu mongoliensis that roamed what is now Mongolia around 86 million years ago. (Image credit: Julius Csotonyi)

 

Meet 'Dragon prince' — the newly discovered T. rex relative that roamed Mongolia 86 million years ago

By Chris Simms Live Science, June 12, 2025

A new species of dinosaur that was probably a princely ancestor of T. rex, the king of the dinosaurs, has been identified from fossils excavated in Mongolia.

Scientists have identified a never-before-seen species of dinosaur called the dragon prince — a prehistoric predator that set tyrannosaurs on the path to ruling Earth. This newly discovered relative of Tyrannosaurus rex came to light after researchers re-examined fossils found in Mongolia.

Its existence sheds light on the story of tyrannosaur dinosaurs and how they evolved and spread.

The scientists named the dinosaur the dragon prince of Mongolia (Khankhuuluu mongoliensis), with the genus name based on the Latinization of the Mongolian words for prince and dragon. Their findings were published Wednesday (June 11) in the journal Nature.

"They [tyrannosauroids] were the princes before they took the mantle of kingship," study co-author Jared Voris, a researcher at the University of Calgary in Canada, told Live Science.

Tyrannosauroids were giant apex predators that walked on two legs, had huge heads with sharp teeth and tiny arms. They are part of the larger tyrannosauroid family and were thought to have evolved from smaller species — but until now there has been little fossil evidence to support this idea.

So, Voris set out for Mongolia to examine partial tyrannosauroid skeletons that had been excavated decades ago but not yet fully examined. The specimens that really caught Voris' eye were found in Mongolia in 1972 and 1973 and described in a scientific paper in 1977, when the individuals were identified as the already known genus Alectrosaurus.

But after being reexamined, "I realized it was something completely different than anything we'd ever seen," Voris said. "And it actually represented the ancestor of all of our big apex predatory tyrannosaurs that we find both here in Alberta and in Mongolia and China."

K. mongoliensis was far smaller than T. rex   

The dragon prince lived 86 million years ago and looked much like a tyrannosaur, but it was only about 13 feet (4 meters) long, weighing in at 1,650 pounds (750 kilograms). Many later tyrannosaurs were much bigger, with T. rex reaching 41 feet (12.5 m) long and weighing up to about 23,000 pounds (10,400 kg). The dragon prince also had a smaller head and longer arms compared to later tyrannosaurs.

"It's a nice new discovery giving us a better sense of what this intermediate phase of tyrannosaur history is like," Thomas Holtz, a vertebrate paleontologist at the University of Maryland, who wasn't part of the team, told Live Science.