T.Rex Evolutionary Progenitor Found
Gonna have to bring more potato salad to the tyrannosaur family reunion potulck, apparently
A recent article published in Nature reveals an exciting dino discovery: Paleontologist Jared Voris was researching a collection of 86 million-year-old dinosaur fossils that had been uncovered in Mongolia in the 1970’s and realized that they had been miscategorized. Based on the available evidence of the time of discovery, the bones had been filed as Alectrosaurus. But during his analysis of the skeletal remains, Voris realized that they were, in fact, that of an undiscovered form of early tyrannosaur. The discovery helps shed light on how Tyrannosauridae, including the prominent apex predator Tyrannosaurus Rex, evolved over the millions of years that would follow.
This newly-discovered species was christened Khankhuuluu mongoliensis, which translates to “dragon prince from Mongolia.” Kirk is unamused.
Khankhuuluu predates the Tyrannosaurus Rex by about 20 million years and was more slender and smaller—about 13 feet long, or the size of a juvenile T. Rex. Khankhuuluu were fast hunters with sharp, blade-like teeth, and long, shallow jaws designed for quick biting rather than hard clamping. Their speed and size meant that Khankhuuluu lived in the shadows of larger apex predators of their era. The discovery of the fossils along with their location gives a picture of how the species adapted and colonized regions from prehistoric Asia into the North American landmass via land bridge and helps shed light on the evolutionary trajectory of different tyrannosaur subgroups as they developed, migrated and spread during the Cretaceous period.
Recent fossil discoveries such as this are proving that instead of a simple line of evolution from early tyrannosaurs to T. rex, there was a wildly branching evolutionary tree consisting of different tyrannosaur subgroups that came and went through the Cretaceous. “Tyrannosaurs evolved into those giant apex predators and diversified very rapidly across North America,” Voris says. While some species remained slender and preyed on smaller animals, others became the large apex predators that hunted the largest dinosaurs of their time. For example, the largest T. Rex specimen ever found, nicknamed “Scotty,” roamed in the area of what is now Saskatchewan, Canada about 66 million years ago; he was nearly 42 feet long and estimated to weigh about 19,500 pounds. While T. Rex were the largest carnivores of their environment, other tyrannosaurus species also existed during the late Cretaceous period. The exact number of genera is controversial, with some experts recognizing as few as three and others specifying as many as fifteen.
A body of new fossil evidence suggests that as tyrannosaurs branched and evolved in North America, they would again cross back into Asia around 79 and 78 million years ago. Environmental adaptations would spark another evolutionary branch, with some staying the slender, rapid hunters while others growing larger skulls that could crush bones. This latter group would again cross back into the North American region, becoming the ancestor for Tyrannosaurus Rex. It appears that the rise of one the planet’s largest and most fearsome carnivores was due to several migrations between North America and Asia that took place over a period of 20 million years. Were it not for the asteroid impact the abruptly ended the Cretaceous 66 million years ago, tyrannosaurs would probably have kept changing and evolving. While that certainly would have impacted the rise of mammals and eventually that of humans as a dominant species on the planet in the present day, I can’t help imaginging what humans living alongside tyrannasaurs would look like today.
After the Khankhuuluu mongoliensis news broke last week, I knew I had to do my own swaggering T. Rex animation for Wonkette. However, for the sake of scientific accuracy, I have to point out that my rendering of a T. Rex is, well… not based on what the latest research suggests about their gait and appearance. The lovely and talented Canadian paleoartist/biological illustrator Danielle Dufault from Animalogic has an deeper dive into how findings from the paleontological community is shaping our current understanding of what these large and fearsome creatures probably looked like (far less snaggle-toothed than that of a Martini imagining, apparently). I know there’s a lot of excitement in the last decade or so imagining a feathered T. Rex, but as per the latest science there is still a lot to learn about whether these giant dinosaurs were feathered and to what extent. They also had lips! Dufault has the deets in the video embedded below.
Expect to pay if you go out for drinks with that guy.
Eat them up, yum!