Science, Tech, Math › Animals & Nature Lythronax Share Flipboard Email Print Lythronax (Lukas Panzarin). Animals & Nature Dinosaurs Carnivores Basics Paleontologists Dinosaurs & Birds Herbivores Marine Reptiles Prehistoric Mammals Amphibians Birds Habitat Profiles Mammals Reptiles Wildlife Conservation Insects Marine Life Forestry Evolution View More By Bob Strauss Science Writer B.S., Cornell University Bob Strauss is a science writer and the author of several books, including "The Big Book of What, How and Why" and "A Field Guide to the Dinosaurs of North America." our editorial process Bob Strauss Updated July 03, 2019 Name Lythronax (Greek for "gore king"); pronounced LITH-roe-nax Habitat Woodlands of North America Historical Period Late Cretaceous (80 million years ago) Size and Weight About 24 feet long and 2-3 tons Diet Meat Distinguishing Characteristics Moderate size; long skull; foreshortened arms About Lythronax Despite what you may have read in the press, the newly announced Lythronax ("gore king") isn't the oldest tyrannosaur in the fossil record; that honor goes to pint-sized Asian genera like Guanlong that lived tens of millions of years earlier. Lythronax does, however, represent a crucial "missing link" in tyrannosaur evolution, since its bones were unearthed from a region of Utah that corresponds to the southern portion of the island of Laramidia, which straddled North America's shallow Western Interior Sea during the late Cretaceous period. (The northern part of Laramidia, by contrast, corresponds to the modern-day states of Montana, Wyoming, and North and South Dakota, as well as parts of Canada.) What the discovery of Lythronax implies is that the evolutionary split leading to "tyrannosaurid" tyrannosaurs like T. Rex (to which this dinosaur was closely related, and which appeared on the scene over 10 million years later) occurred a few million years earlier than was once believed. Long story short: Lythronax was closely related to other "tyrannosaurid" tyrannosaurs of southern Laramidia (most notably Teratophoneus and Bistahieversor, in addition to T. Rex), which now appear to have evolved separately from their neighbors in the north--meaning there may be many more tyrannosaurs lurking in the fossil record than previously believed.