“King of Gore” (Lythronax argestes) had looks and a lifestyle to match its name. Described in the latest issue of the journal PLoS ONE, it was by far the scariest large predatory dinosaur alive at that time during the Late Cretaceous Period.
“We thought that Lythron, or gore in Greek, exemplified its presumed lifestyle as a predator with its head covered in the blood of a dead animal,” lead author Mark Loewen, a research associate at the Natural History Museum of Utah, told Discovery News. The dino co-existed with the largest alligator that ever lived, 40-foot-long Deinosuchus, which it probably avoided in favor of easier prey.
“(Lythronax's) forward-facing eyes, powerful limbs and large size would have made it an efficient hunter of both duckbilled dinosaurs and horned dinosaurs like Diabloceratops,” added co-author Joseph Sertich, curator of Vertebrate Paleontology at the Denver Museum of Nature and Science.
“A mouthful of knife-edged teeth set in powerful jaws would have made short work of potential prey, carving out huge chunks of flesh and bone to swallow hole,” Sertich continued.
A Bureau of Land Management employee named Scott Richardson first discovered the dinosaur’s fossilized skeleton. For the study, Loewen and his team excavated the remains and analyzed them. They compared 501 skeletal features of Lythronax with those of 54 different other species of known, carnivorous dinos. The paleontologists found that Lythronax is most closely related to T. rex and another dinosaur known as Tarbosaurus bataar.
In terms of size, Sertich said that Lythronax was smaller than T. rex, reaching around 30 feet in length as opposed to 40 plus feet. Lythronax was no lightweight, though, and would have tipped the scales at about nearly 3 tons.
Both “King of Gore” and “Tyrant Lizard King” had about the same number of teeth set in a wide skull. Their snouts were short and narrow, but widened at the eyes to permit binocular vision.
“Binocular vision requires eyes set slightly apart that have overlapping fields of view, meaning the same eye sees the same thing at the same time from a slightly different perspective,” Loewen explained. “This allows the animal to have depth perception.”
Although T. rex emerged some 10 million years after Lythronax, both lived at a place called Laramidia, which existed along the western shores of a great seaway that separated North America. The tyrannosaurid dinosaurs likely evolved in isolation on the island continent, with incursions of the seaway separating small areas of land from each other. This further allowed different species of dinosaurs to evolve on different parts of the landmass.
Sertich explained that rising mountains and fluctuating sea levels made for a very dynamic landscape, which set the stage for the evolution of unique dinosaurs and their ecosystems.
“Laramidia over its history was a paradise of dinosaur evolution,” Loewen said. “Many groups, including ankylosaurs, ceratopsians, hadrosaurs, ornithomimids and tyrannosaurs underwent radiations on this island continent. In some ways, it was the crucible of evolution during the Late Cretaceous.”
The researchers unearthed the remains of a new specimen of Teratophoneus that is the most complete tyrannosaur from southern Laramidia. Together, all of the fossils suggest that the evolution of T. rex and its relatives was much more complex than previously thought.
Read more at Discovery News
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