This T. rex ancestor is "missing link" to apex predators, scientists say

Tyrannosaurus Rex, king of the dinosaurs

Tyrannosaurus Rex, king of the dinosaurs 08:11

More than 85 cardinal years ago, a smaller-bodied ancestor of the Tyrannosaurus rex roamed the plains of Mongolia. The dinosaur's individuality was chartless — until now.

In a study published Wednesday successful Nature, scientists picture the recognition of a caller tyrannosauroid named Khankhuuluu mongoliensis. Apex predators, including the T. rex, yet arose from these smaller-bodied tyrannosauroids, the study's researchers said.

"This species, Khankhuuluu, is the missing nexus betwixt smaller and earlier forms and the larger apex predatory tyrannosaurs," paleontologist Darla Zelenitsky, a prof astatine the University of Calgary and survey co-author, told CBS News. 

Darla Zelenitsky, subordinate prof of dinosaur paleontology and main dinosaur researcher successful the Department of Geoscience, and Jared Voris, post-doctoral scholar, published a insubstantial successful the subject diary "Nature" astir the improvement of the Tyrannosaurus. Riley Brandt, University of Calgary

The Khankhuuluu's skeleton was discovered successful Mongolia successful the Gobi Desert successful 1972 oregon 1973, but wasn't studied scientifically until a fewer years later, Zelenitsky said. The remains were identified by Mongolian paleontologist Altangerel Perle arsenic Alectrosaurus olsoni, different obscure species. After it was misidentified, the bones became portion of a depository postulation and were comparatively untouched for astir 50 years. 

Referred to arsenic mid-grade tyrannosauroids, these smaller-bodied predators were evolutionary intermediates, the survey found. During the play erstwhile Khankhuuluu lived successful Mongolia, the tyrannosaurs began increasing larger and taking connected the features of apex predators. Not overmuch other is known astir these elusive tyrannosauroids owed to fragmentary fossil remains, but researchers said the dinosaurs weighed astir 1,700 pounds. They were 1 of the larger predators successful the ecosystem astatine the time. 

"It's fundamentally the contiguous ancestor of the tyrannosaur family," Zelenitsky said.

A astonishment discovery 

University of Calgary postdoctoral student and survey co-author Jared Voris traveled to Mongolia a fewer years earlier to probe the bones of assorted tyrannosaurs and, successful the process, gained entree to spot the bones of what they would aboriginal find are the Khankhuuluu. 

Voris thought the remains could beryllium thing important, arsenic helium often saw references to the specimens popular up, but aft helium started examining the bones, helium knew it could beryllium thing special. While studying the idiosyncratic characteristics of the bones, 1 of the things helium noticed was that the Khankhuuluu's teeth couldn't crush bone, Voris said, a defining diagnostic of the larger apex predatory Tyrannosaurus. 

"This carnal had features we had ne'er seen earlier successful much of our iconic tyrannosaurs," Voris said.

He texted Zelenitsky from Mongolia that helium "thought it could beryllium a caller species." Zelenitsky said she responded, "I said, large going, support looking astatine this truthful we tin beryllium definite this is simply a caller species." 

An creator rendering of a caller tyrannosauroid named "Khankhuuluu." Image: Julius Csotonyi

The 2 paleontologists aren't caller to groundbreaking technological discoveries — they've had several. In 2023, Zelenitsky was portion of a squad that identified a Tyrannosaurus fossil with a repast successful its stomach, and Voris discovered a caller taxon of tyrannosaurid dinosaur, Thanatotheristes degrootorum — whose genus sanction translates to "Reaper of Death."

"Rewriting a household past of tyrannosaurs"

These Asian tyrannosauroids yet crossed implicit into North America utilizing a bluish onshore span betwixt Alaska and Siberia, Zelenitsky said. Dinosaurs utilized these onshore bridges, which appeared periodically implicit the past 100 cardinal years, to question betwixt Asia and North America. 

And from it, these tyrannosauroids evolved and morphed into apex predators. T. rex is the deadliest onshore predator ever to live, and determination has agelong been a fascination with the dinosaur that has been extinct for astir 66 cardinal years.  

Khankhuuluu, a recently discovered ancestor of the larger Tyrannosaurus family. Image credit: Jared Voris

The survey co-authors said the caller recognition shows determination are inactive large discoveries to beryllium made successful science. "What truly started conscionable arsenic a find of a caller taxon ended up with america benignant of rewriting a household past of tyrannosaurs," Zelenitsky said.

• Tyrannosaurus Rex
• Dinosaur