Khankhuuluu

Discovered After 50 Years! The Meaning of the “Mongolian Prince”

The discovery of Khankhuuluu has a long history.

An Unidentified Fossil Slumbering in a Museum

The fossil itself was excavated in the Gobi Desert by a joint Soviet-Mongolian expedition in the 1970s.
However, at the time, it was presumed to be “a species of Alectrosaurus,” and it sat slumbering in a museum storage room for half a century without detailed classification.

Revealed as a New Species in a 2023 Re-examination

The turning point came in 2023.
When Jared Voris, a graduate student at the University of Calgary, conducted a re-examination, he identified features distinct from Alectrosaurus (such as the shape and cavities of the nasal bone).
As a result of detailed analysis, it was confirmed to be a new genus and species. It was named Khankhuuluu (“prince dragon”) as a “prince” in the lineage leading to the “king,” T. rex.

An Appearance Like an “Eternal Juvenile” and the Key to Evolution

Khankhuuluu lived during the Late Cretaceous period, about 90 to 86 million years ago.
Its appearance bore no resemblance to the later tyrannosaurs.

A Slender, Petite Speedster

Size

Estimated length of about 4 meters (13.1 feet) and weight of 500 to 750 kg (1,100 to 1,650 lbs).
This is less than one-tenth the weight of a Tyrannosaurus.

Characteristics

Instead of thick, bone-crushing teeth, it had “blade-like teeth for tearing flesh,” and possessed “fleet-footed” legs where the tibia was longer than the femur.

Evolution Through Heterochrony

These features are actually strikingly similar to the “juveniles” of large tyrannosaurs.
It is believed that Khankhuuluu adopted a strategy called “paedomorphosis,” maintaining slender, juvenile-like features even as it grew into adulthood.
Through this, unlike the tyrannosaurs that grew massive and stood at the apex, they established their status as “mesopredators” (intermediate predators) that hunted prey with agile movements.

Three Round Trips Between Asia and North America? The Drama of Intercontinental Migration

The discovery of Khankhuuluu has also unraveled the mystery of how tyrannosaurs spread across the globe.
They undertook mass migrations between Asia and North America at least three times.

The First Migration (Up to 85 Million Years Ago)

From Asia to North America.
Ancestors like Khankhuuluu expanded their range and began their own unique evolution in North America.

The Second Migration (Around 79 Million Years Ago)

A “reverse import” from North America back to Asia.
Here, they diverged into the slender “Alioramini tribe” and the power-type “ancestors of Tarbosaurus.”

The Third Migration (Around 73 Million Years Ago)

The power-type that evolved in Asia returned to North America once again.
This line ultimately evolved into the strongest dinosaur in history, Tyrannosaurus rex.

In short, tyrannosaurs had their roots in Asia and were forged into the ultimate apex predators through repeated intercontinental migrations.