Lythronax

Phylogeny: Dinosauria > Saurischia > Neotheropoda > Tetanurae > Avetheropoda > Coelurosauria > Tyrannosauroidea > Pantyrannosauria > Eutyrannosauria > Tyrannosauridae > Tyrannosaurinae > Teratophoneini

Overview: Tyrannosaurs as a lineage first appear in the fossil record during the Middle Jurassic, at a time when other theropod groups were dominant. For much of their existence, with a small handful of exceptions, tyrannosaurs were smaller-sized predators living in the shadow of the megalosaurids and later the allosauroids. However, as those lineages began their decline, some tyrannosaurs evolved to fill those niches themselves, obtaining ever larger sizes. The largest were in the family Tyrannosauridae, to which the famous Tyrannosaurus rex belonged. Lythronax, having lived over eighty million years ago, was one of the earliest confirmed members of the family. It was a lot smaller than Tyrannosaurus, at maybe seven meters long, but easily reigned as the top predator of its own local environment. Its fossils are known from Utah’s Wahweap Formation, so it would’ve lived alongside dinosaurs like Diabloceratops – a ceratopsid and potential food source.

In its general appearance, Lythronax was similar to most other tyrannosaurids. It was a strongly built biped with a large skull, equipped with powerful jaws. Lythronax had a notably short, but deep snout in comparison to most other tyrannosaurids. The arms were short, but muscular, bearing only two digits on each hand, each bearing a curved claw. For the most part, Lythronax and its kin relied mainly upon their jaws to kill. Researchers usually divide the Tyrannosauridae into two major subfamilies called the Albertosaurinae and the Tyrannosaurinae. Lythronax belonged to the latter, so it was closer to Tyrannosaurus than to Albertosaurus or Gorgosaurus. Its closest relatives were dinosaurs like Teratophoneus and Dynamoterror, which along with Lythronax are classified within a tribe called the Teratophoneini. Members of this group mainly lived in what is now the southwest of the United States. Described in 2013, the generic name of Lythronax means “king of gore” in Latin, which fits a trend of giving imposing names to tyrannosaurs.