A remarkable new dinosaur discovery in a Mongolian museum collection is shedding fresh light on the evolutionary journey of the mighty tyrannosaurs — and, according to scientists, is effectively rewriting their family tree.
As reported by the BBC, researchers have concluded that two skeletons, dating back 86 million years, belong to a species now believed to be the closest known ancestor of all tyrannosaurs — the family of fearsome carnivorous dinosaurs that includes the iconic Tyrannosaurus rex (T. rex).
The newly identified species has been named Khankhuuluu mongoliensis (pronounced khan-KOO-loo mongoliensis), which translates to “Dragon Prince of Mongolia.”
Published in the journal Nature, this discovery provides vital clues about how early tyrannosaurs evolved into the apex predators that dominated ecosystems across North America and Asia until the mass extinction that wiped out the dinosaurs.
The “Dragon Prince” of Tyrannosaurs
“The name ‘Prince’ reflects that it was an early, smaller member of the tyrannosaur lineage,” explains Professor Darla Zelenitsky, a paleontologist at the University of Calgary, Canada. Tyrannosauroids, as they are formally called, are a superfamily of two-legged carnivorous dinosaurs.
However, the first tyrannosauroids were not the towering giants we often imagine. Instead, as PhD candidate Jared Voris, who led the study alongside Professor Zelenitsky, describes: “They were quite small, nimble predators that lived in the shadows of larger top carnivores.”
Khankhuuluu represents a crucial evolutionary bridge between these small, agile Jurassic hunters and the colossal giants like T. rex. Weighing around 750 kilograms (about 1,650 pounds), it was still dwarfed by an adult T. rex, which could be up to eight times heavier.
“This is a transitional fossil,” says Zelenitsky, “linking early ancestors to the later, more powerful tyrannosaurs.”
She adds, “It helped us rethink the tyrannosaur family tree and rewrite what we know about their evolution.”
A Bite Built for Dominance
The new species shows early evolutionary traits that paved the way for tyrannosaurs to become apex predators — particularly in the skull structure that enabled their famously bone-crushing bite.
Voris elaborates:
“We see features in the nasal bone that, over time, led to the development of that extremely powerful bite force that tyrannosaurs are known for.”
This trait allowed T. rex and its relatives to tackle larger prey and even crush through bone, giving them a lethal advantage at the top of the food chain.
Rediscovered Fossils, New Insights
The two partial skeletons used in the study were actually unearthed in Mongolia in the early 1970s. Initially, they were classified as belonging to a known species, Alectrosaurus. But when Voris re-examined them decades later, he noticed distinct features pointing instead to a true tyrannosaur and setting the fossils apart as a new species.
“I remember getting a message from Jared — he was convinced it was a new species,” recalls Zelenitsky.
How Tyrannosaurs Conquered Continents
Back in the Late Cretaceous, tyrannosaurs were able to move between North America and Asia thanks to land bridges that once connected Siberia and Alaska. This migration allowed them to spread and adapt to different ecosystems, speeding up their evolution.
Voris notes:
“Moving between continents essentially accelerated the evolution of diverse tyrannosaur groups for millions of years.”
As Zelenitsky puts it:
“This discovery reminds us that before tyrannosaurs became kings, they were princes first.”
