New Predatory 'King of Gore' Dinosaur Reveals More About its Cousin, T. Rex

Millions of years ago, a predator and fearsome dinosaur roamed the Earth. Now, archaeologists have unearthed its remains, revealing a new species of tyrannosaur that shows a little bit more about the evolutionary origins of the massive Tyrannosaurus rex.

The new species probably lived during the Late Cretaceous Period, which occurred between 95 to 70 million years ago. Belonging to the same evolutionary branch as the Tyrannosaurus rex, this new species is named Lythronax, which translates as "king of gore." Although previously paleontologists thought this type of wide-skulled tyrannosaurid only appeared 70 million years ago, it appears that Lythronax evolved at least 10 million years earlier.

The massive species lived on Laramidia, along the western shores of the great seaway that separated North America. This particular landmass held a vast array of unique dinosaur species and served as the crucible of evolution for iconic dinosaur groups such as the horned and duck billed dinosaurs. It's also very likely that the tyrannosaurid dinosaurs also evolved on this landmass.

Lythronax actually had a much wider skull at the eyes and a narrow short snout when compared to its contemporaries. This made it similar to its relative, the T. rex, which lived 10 to 12 million years later.

"The width of the back of the skull of Lythronax allowed it to see with an overlapping field of view-giving it binocular vision-very useful for a predator and a condition we associate with T. rex," said Mark Loewen, the study's lead author, in a news release.

In fact, what's most interesting about this new species is what it can tell paleontologists about the tyrannosaurid dinosaurs as a whole. The researchers analyzed the evolutionary relationships, geologic age and geographic distribution of the tyrannosaurid dinosaurs. In the end, they found that the tyrannosaurids diversified between 95 to 80 million years ago, during a time when North America's interior sea was at its widest extent. This means that the incursion of the seaway onto large parts of low-lying Laramidia would have separated small areas of land from each other. This, in turn, would have allowed different species of dinosaurs to evolve in isolated locations. In fact, as the seaway gradually retreated, these differences in dinosaur species may have been reinforced by climate variations, differences in food sources and other factors. This explains why the iconic Late Cretaceous dinosaurs of western North America are so different from those of the same age on other continents.

The findings reveal a little bit more about the origin of the tyrannosaurids. More specifically, the new species shows how T. rex first emerged. This, in turn, may inform future studies on these large, carnivorous dinosaurs.

The findings are published in the journal PLOS One.