Paleontologists discover new species from this family in the US

Nov 7, 2013 13:42 GMT  ·  By
L. argestes featured forward-looking eyes and a narrower snout than its descendant, the T. Rex
   L. argestes featured forward-looking eyes and a narrower snout than its descendant, the T. Rex

A paper published in the November 6 issue of the open-access journal PLOS ONE details the discovery of a dinosaur that may have been Tyrannosaur Rex's grandfather. The fossilized remains of the new species also shed some light on the evolutionary history of this remarkable group of dinosaurs.

The discovery was made at a dig site within the Grand Staircase-Escalante National Monument (GSENM), in southern Utah, by experts with the Natural History Museum of Utah and the University of Utah. The team worked closely with colleagues from universities around the country for this study.

Between 95 and 70 million years ago, the area that now makes up Utah belonged to a continent called Laramidia. The landmass was bordered to the east by a shallow sea that had flooded the North American continent during the Late Cretaceous Period, Science Daily reports.

The new species, called Lythronax argestes – which roughly translates into “the King of Gore” of the American Southwest – is part of the same evolutionary branch as its more famous descendant, but predated T. Rex by around 10 million years, the team determined.

Tyrannosaurs lived during the Jurassic and Cretaceous periods, and produced species that reached the apex of the food chain at the time. Among these natural-born predators, L. argestes showcases a series of unique traits that probably made it extremely dangerous to its prey.

Its snout was shorter and narrower than that of a T. Rex, while the back of its skull was rather wide. Unlike many other dinosaurs, it featured forward-looking eyes. Experts believe this species developed around 80 million years ago, about 10 million years before the T. Rex appeared.

“The width of the back of the skull of Lythronax allowed it to see with an overlapping field of view – giving it the binocular vision – very useful for a predator and a condition we associate with T. rex,” says Dr. Mark Loewen, who is the lead author of the study and a research associate at NHMU.

L. argestes' range may have been limited to Laramidia, a continent known for its unique dinosaurs and seclusion from other landmasses. This landmass is famous for the horned and duck billed dinosaurs that eventually developed here.

Researchers now believe that the unique isolation of Laramidia may have contributed to the emergence and development of numerous dinosaur species not found anywhere else. They now plan to continue investigating the Grand Staircase-Escalante National Monument in hopes of finding more fossils.