Newly recognized T. rex ancestor is

Greater than 85 million years in the past, a smaller-bodied ancestor of the Tyrannosaurus rex roamed the plains of Mongolia. The dinosaur’s identification was unknown — till now.

In a research revealed Wednesday in Nature, scientists describe the identification of a brand new tyrannosauroid named Khankhuuluu mongoliensis. Apex predators, together with the T. rex, ultimately arose from these smaller-bodied tyrannosauroids, the research’s researchers mentioned.

“This species, Khankhuuluu, is the lacking hyperlink between smaller and earlier types and the bigger apex predatory tyrannosaurs,” paleontologist Darla Zelenitsky, a professor on the College of Calgary and research co-author, informed CBS Information. 

The Khankhuuluu’s skeleton was found in Mongolia within the Gobi Desert in 1972 or 1973, however wasn’t studied scientifically till a number of years later, Zelenitsky mentioned. The stays had been recognized by Mongolian paleontologist Altangerel Perle as Alectrosaurus olsoni, one other obscure species. After it was misidentified, the bones turned a part of a museum assortment and had been comparatively untouched for nearly 50 years. 

Known as mid-grade tyrannosauroids, these smaller-bodied predators had been evolutionary intermediates, the research discovered. Throughout the interval when Khankhuuluu lived in Mongolia, the tyrannosaurs started rising bigger and taking over the options of apex predators. Not a lot else is thought about these elusive tyrannosauroids as a result of fragmentary fossil stays, however researchers mentioned the dinosaurs weighed round 1,700 kilos. They had been one of many bigger predators within the ecosystem on the time. 

“It is basically the instant ancestor of the tyrannosaur household,” Zelenitsky mentioned.

A shock discovery 

College of Calgary postdoctoral scholar and research co-author Jared Voris traveled to Mongolia a number of years earlier to analysis the bones of varied tyrannosaurs and, within the course of, gained entry to see the bones of what they might later decide are the Khankhuuluu. 

Voris thought the stays may very well be one thing essential, as he typically noticed references to the specimens pop up, however after he began inspecting the bones, he knew it may very well be one thing particular. Whereas finding out the person traits of the bones, one of many issues he seen was that the Khankhuuluu’s tooth could not crush bone, Voris mentioned, a defining attribute of the bigger apex predatory Tyrannosaurus. 

“This animal had options we had by no means seen earlier than in additional of our iconic tyrannosaurs,” Voris mentioned.

He texted Zelenitsky from Mongolia that he “thought it may very well be a brand new species.” Zelenitsky mentioned she responded, “I mentioned, nice going, preserve taking a look at this so we may be positive it is a new species.” 

The 2 paleontologists aren’t new to groundbreaking scientific discoveries — they’ve had a number of. In 2023, Zelenitsky was a part of a staff that recognized a Tyrannosaurus fossil with a meal in its abdomen, and Voris found a brand new species of tyrannosaurid dinosaur, Thanatotheristes degrootorum — whose genus identify interprets to “Reaper of Loss of life.”

“Rewriting a household historical past of tyrannosaurs”

These Asian tyrannosauroids ultimately crossed over into North America utilizing a northern land bridge between Alaska and Siberia, Zelenitsky mentioned. Dinosaurs used these land bridges, which appeared periodically over the previous 100 million years, to journey between Asia and North America. 

And from it, these tyrannosauroids advanced and morphed into apex predators. T. rex is the deadliest land predator ever to stay, and there has lengthy been a fascination with the dinosaur that has been extinct for about 66 million years.  

The research co-authors mentioned the brand new identification reveals there are nonetheless large discoveries to be made in science. “What actually began simply as a discovery of a brand new species ended up with us form of rewriting a household historical past of tyrannosaurs,” Zelenitsky mentioned.