Step aside, tyrannosaurs, there’s a new king of the Mesozoic world.
Paleontologists in Uzbekistan Wednesday unearthed a 90-million-year-old rock containing the remains of a newly discovered dinosaur that is theorized to have once terrorized smaller species of tyrannosaurs: It’s the 30-foot long carcharodontosaur named the Ulughbegsaurus uzbekistanensis.The new dinosaur, identified by a singular upper jawbone and serrated teeth, was first revealed in Royal Society Open Science by University of Tsukba paleontologist Kohei Tanaka, University of Calgary paleontologist Darla Zelenitsky and their colleagues.
“This is one new bone, and really just part of a bone, but its importance far eclipses its looks,” said University of Edinburgh paleontologist Stephen Brusatte, who commented on the discovery but did not participate in its findings.
Zelenitsky goes on to predict the newly discovered “shark-toothed lizards” were allosauroids that were natural predators over tyrannosaurs, limiting their population growth.
The remains were found in the Bissekty Formation, 90- to 92-million-year-old rock formations that have buried the remains of a multitude of dinosaur species includes other small tyrannosaurs, allosauroids, and sauropods.
“The Bissekty Formation represents one of the best-known ecosystems in Europe and Asia of its time,” Zelenitsky said.
One such tyrannosaur found in the Bissekty Formation includes Timurlengia, a 10-foot-long predator that would have conflicted with the Ulughbegsaurus.
“There may have been a complex interplay among Ulughbegsaurus and other, smaller predatory dinosaurs,” Zelenitsky added.
Other apex predators in the same Mesozoic time period have been found in a 96-million-year-old rock in southeastern Utah, including another small tyrannosaur, named Moros, and a large carcharodontosaurs named Siats.
It was only until after these larger carcharodontosaurs, like the Ulughbegsaurus, moved out of the region that the small tyrannosaurs grew into the larger, more dominantly known species.
In Early Cretaceous China around 125 million years ago, for example, these larger predators did not exist in the environments to limit the growth of tyrannosaurs. This led to the development of the Yutyrannus, a 30-foot-long tyrannosaur.
Paleontologists are not certain as to what led to the absence or fallout of the carcharodontosaurs, a mystery that might one day be explained, as it is not likely the smaller predators suddenly overtook their larger counterparts.
“I think that any finds we can make in or around the 90- to 80-million-year-old window can help shed light on this poorly-known interval of dinosaur-dominated ecosystems,” Zelenitsky detailed.
“Given that allosauroids were holding back tyrannosaurs for so many tens of millions of years,” Brusatte added, “I can’t envision that tyrannosaurs suddenly figured out how to out-compete the allosauroids.”