Scientists have discovered a previously unknown species of shark-toothed predatory dinosaur that would have been the T. rex of its day.
It belongs to the family of dinosaurs known as carcharodontosaurs, best known for their shark teeth. Called Ulughbegsaurus uzbekistanensis, it was at least seven meters long, weighed more than a ton and would have roamed Central Asia some 90 million years ago.
The jaw fossil is believed to have been unearthed in the 1980s and found at the State Geological Museum in Tashkent, Uzbekistan, but its significance was not recognized until 2019, said Darla Zelenitsky, associate professor of dinosaur paleobiology at the University of Calgary in Canada.
Researchers from Canada, Japan, and Uzbekistan named the new genus and species Ulughbegsaurus (oo-LOOG-bek-SAW-rus) uzbekistanensis, after 15th-century mathematician and astronomer Ulugh Beg.
“Over 90 million years ago, the apex predators of Asian and North American ecosystems were often large species of carcharodontosaurs known as shark-toothed dinosaurs, which were later replaced by large species of T-like tyrannosaurs. rex, somewhere around 80 to 90 million years,” Zelenitsky said in a statement.
“Both groups of dinosaurs were meat eaters, had sharp teeth, and walked on two legs, although tyrannosaurs were generally stronger.”
How tyrannosaurs evolved to replace carcharodontosaurs at the top of the food chain in these regions remains unclear. Apex predators are generally fewer in number than animals that prey, which could explain why their fossil remains are harder to find in some ancient ecosystems, Zelenitsky explained.
Zelenitzky said Ulughbegsaurus would have shared the ecosystem with a small species of tyrannosaurus called Timurlengia.
“All the evidence suggests that species of Carcharodontosaurs were outpacing or keeping down species of tyrannosaurs in ecosystems in Asia and probably North America, just before their extinction, about 90 million years ago,” Zelenitsky said.
The extinction of carcharodontosaurs allowed tyrannosaur species to assume the role of vertex predator in Asia and North America from 80 million to 90 million years ago. They persisted in large forms like T. rex, until a large asteroid hit Earth about 66 million years ago, dooming most dinosaurs to extinction.
The research was published in the Royal Society Open Science magazine on Tuesday.
(Text translated, read original in English here)