Past Time

Tyrannosaurus rex is a dinosaur celebrity, a villain in most dinosaur movies and documentaries, but where did the massive beast come from? On November 6, 2013, a team of paleontologists including our expert in this episode, Dr. Randy Irmis from the University of Utah and the Natural History Museum of Utah, published two new skeletons of Tyrannosaurus’s close kin: Teratophoneus and Lythronax. The skeletons reveal Tyrannosauridae (T. rex’s family) was diverse 80 million years ago with different species living in different parts of Western North America. The new genus Lythronax is the oldest member of the Tyrannosauridae even though its anatomy closely resembles the last species of tyrannosaurid, T. rex. A massive sea divided Western North America, called Laramidia, from Eastern North America, called Appalachia. Laramidia was a long, skinny continent that ran from Alaska to Baja California. In general, in modern ecosystems, the larger the land-mass, the more species can live on it. Laramidia was one-tenth the si