Graduate Student Discovers Cannibalized Tyrannosaurus Bone

His findings may not support the Loma Linda emphasis on plant-based nutrition, but a 26-year-old graduate student in the department of earth and biological sciences at Loma Linda University School of Medicine (LLUSM) recently discovered that Tyrannosaurus rex, the ferocious fanged dinosaur of the Cretaceous era, was a cannibal. Matthew McLain presented his findings at the 2015 annual meeting of the Geological Society of America, which was held in Baltimore, Maryland, November 1-4. He also authored an abstract, which the society published under the title, “Tyrannosaur Cannibalism: a Case of a Tooth-Traced Tyrannosaur Bone in the Lance Formation of Eastern Wyoming.” “A lot of paleontologists have been suspecting that cannibalism was going on in tyrannosaurs,” McLain states. According to the article, the yellow-brown fossil “is heavily marked with several long grooves on its cortical surface all concentrated on the bone’s widest end.” To the untrained eye, the grooves look like a series of erratic scrape marks, yet on closer examination—and especially when viewed under a microscope—they reveal the serrated patterns of the predatory animal’s teeth. The paleontological smoking gun is not entirely without controversy, however. “Most people say there’s only one species of tyrannosaur in the Lance Formation,” McLain reports, “and that is Tyrannosaurus rex, or T. Rex. But a few say there is also another species known as Nanotyrannus lancensis. Based on the size of this bone, this could possibly be a case of T. rex eating a Nanotyrranus. But it could also be a juvenile T. rex being eaten by an adult. Most paleontologists think Nanotyrranus is just a juvenile T. rex, anyway.” To find out, McLain plans to compare the bone to Tyrannosaurus bones in other collections. If that doesn’t resolve the mystery, he says researchers may slice through the sample and examine it in cross-section to see if the animal in question was finished growing at the time it died. “If it wasn’t, most people will say it’s a young T. Rex,” he says. “I’m inclined to agree with that and most researchers are, too.” One of McLain’s two mentors on the Lance Formation dig—Arthur V. Chadwick, PhD, research professor of biology and geology at Southwestern Adventist University—suggests that Nanotyrannus may actually be a new species. His other mentor on the project, Leonard R. Brand, PhD, professor of biology and paleontology at LLUSM, says that because of the current disagreement over whether Nanotyrranus is a separate species, it can be difficult to ascertain for certain the type of dinosaur the bone represents. In addition to McLain, Chadwick, and Brand, Bethania Silveiro, a PhD student at LLUSM, and David Nelsen, professor of biology at Southern Adventist University, contributed to the evaluation of the bone. Even though the exact type of tyrannosaur is somewhat in question, McLain says it’s a pretty amazing finding just the same. “This finding is telling us a lot about the way dinosaurs were behaving,” he says. “Since this was one of the bones of the hind leg, we can assume that it was eaten after the animal was already dead. We do see cannibalism in some modern animals like sharks and lions. This is not the only example of Tyrannosaurus cannibalism, but it is the best example.” McLain says the Lance Formation runs through portions of Wyoming and the Dakotas. “It’s more or less the same as the Hell Creek Formation, which also extends into Montana,” he adds. “The Lance Formation signals the end of the Cretaceous Period, the time of the last dinosaurs.” Although there were 30 to 40 people working at the site at the time the fossil was found, McLain says only three or four of them immediately grasped the significance of the find. “For me, the amazing thing is that 100 years ago, people would have chucked this broken bone away,” he says, reflecting on the fact that current advancements in protocols and technology allow a much higher degree of certitude than in the past. “I think it’s really fascinating what you can learn from a broken bone.” McLain is scheduled to graduate with a PhD degree in earth sciences in June, 2016. He hopes to continue studying dinosaurs throughout his career. “I want to teach,” he concludes, “and I’d like to do research as well.”