New Dinosaur Discovery Rewrites T. Rex Family Tree
Mongolian Fossil Reveals Evolutionary Link to King of Predators
A newly identified dinosaur species unearthed in Mongolia is reshaping our understanding of the Tyrannosaurus rex’s origins, offering a crucial glimpse into the evolution of one of history’s most fearsome predators.
A Smaller Relative Emerges
The dinosaur, scientifically named Khankhuuluu mongoliensis, roamed the earth approximately 86 million years ago in what is now southeastern Mongolia. Unlike its colossal descendant, Khankhuuluu was relatively small, reaching only about 750 kilograms – roughly the size of a horse. Its slender build and powerful legs suggest a hunting style focused on speed and agility, similar to modern wolves or coyotes.
The Forerunner of a Giant
According to Dr. Jared Voris, a paleontologist at the University of Calgary, Khankhuuluu mongoliensis gives us the evolutionary window when Tyrannosaurus began to change from small predators to peak predators.
While lacking the bone-crushing jaw strength of T. rex, Khankhuuluu’s elongated and shallow skull indicates it was on the evolutionary path toward becoming a giant predator.
Interestingly, the dinosaur possessed a small horn on its head, which scientists believe may have been used for attracting mates or establishing dominance – a feature that would become more prominent in related species like Albertosaurus and Gorgosaurus.
Ancient Migration Patterns Revealed
Fossil evidence, initially discovered in 1972 and 1973, places Khankhuuluu within the Eutyrannosauria group, the direct ancestors of both the Tyrannosaurini (including T. rex) and Alioramini (known for their elongated snouts, earning them the nickname ‘Pinocchio Rex’). This discovery provides compelling evidence of ancient migration between continents.
Dr. Darla Zelenitsky, also from the University of Calgary, explains, Khankhuuluu Mongoliensis, or his close relatives, is likely to migrate from Asia to North America about 85 million years ago.
This migration is believed to be a key factor in the development of the large tyrannosaurs found in North America, allowing them to evolve largely undisturbed for millions of years before spreading back to Asia and diversifying.
Paleontological discoveries continue to refine our understanding of dinosaur evolution. In 2024, researchers estimated that there were approximately 2.5 billion individual T. rex that lived over the course of its 186 million-year existence ( Smithsonian Magazine, 2024).
Mapping the Tyrannosaurus Evolution
This finding isn’t just about a new fossil; it’s about reconstructing the entire evolutionary map of the tyrannosaurs. Our study provides strong evidence that Tyrannosaurus first evolved in North America as a result of this immigration event,
states Dr. Darla Zelenitsky. Khankhuuluu mongoliensis, or one of his relatives, traveled across the land bridge to North America, where he evolved to be the famous peak predator, Tyrannosaurus Rex.
From this ancestor, one evolutionary path led to the massive predator T. rex, while another resulted in medium-sized dinosaurs with elongated snouts, like the Alioramini.
The study, published in the prestigious journal Nature, represents a significant advancement in paleontological research, offering a new perspective on how the largest land predator in history evolved from agile, horse-sized creatures.