A newly discovered dinosaur has been identified as a cousin of the iconic Tyrannosaurus and is helping paleontologists flesh out the branches of the T. rex family tree.
Lythronax argestes — the first part of the name means "king of gore," and the second refers to a wind from the Southwest described in ancient Greek poetry — stalked the Earth about 80 million years ago, rubbing elbows and tails with giant crocodiles, duck-billed dinosaurs and three-horned dinosaurs like Diaboceratops.
The 2.5-ton L. argestes was 24 feet long and resided on an island continent known as Laramidia, which was formed by a large shallow sea that bisected much of present-day North America.
Now, one particular specimen of L. argestes has turned up in the Grand Staircase-Escalante National Monument in southern Utah. It's the oldest member of the tyrannosaur family ever discovered. Researchers from the Natural History Museum of Utah, the Denver Museum of Nature and Science, and the University of Alberta described the titanic tyrannosaurid in a paper published on Wednesday in the journal PLoS ONE.
What makes L. argestes so special? Its head contains features that are unique among similar dinosaurs of the time, and which bring it closer to T. rex in form. L. argestes has a shorter snout and a skull that's wider at the back. This particular skull shape has its advantages, according to Mark Loewen, a paleontologist at the Natural History Museum of Utah and the lead author on the paper.
SOURCE: Loewen et al. "Tyrant dinosaur evolution tracks the rise and fall of Late Cretaceous oceans." PLoS ONE published online 6 November 2013.