T. Rex Wasn't Always at The Top of The Food Chain. Meet What Came Before

According to new research on the jawbone of the giant predator, about 90 million years ago, a huge meat-eating dinosaur with shark-like teeth and serrated shark-like teeth roamed what is now Uzbekistan.
The beast, which measured 26 feet (8 meters), weighed 2,200 lbs (1, 000 kg). It was longer than an African elephant and larger than a bison.

It was named Ulughbegsaurus uzbekistanensis by researchers after Ulugh Beg (15th century astronomer and mathematician) and sultan of what is now Uzbekistan.

Scientists were shocked to discover that the dinosaur was twice as long and five times more heavy than the ecosystem's apex predator, a Tyrannosaurus.

Related: 10 Coolest Dinosaur Discoveries of 2020

Researchers found the jawbone in Uzbekistan's Kyzylkum Desert during the 1980s. In 2019, they rediscovered it in a Uzbekistan museum collection.

(Julius Csotonyi)

Above: A comparison of the huge carcharodontosaur Ulughbegsaurus and the smaller tyrannosaur Timurlengia.

U. uzbekistanensis' partial jawbone is sufficient to indicate that the animal was either a carcharodontosaur or a shark-toothed dinosaur. These carnivores were relatives and rivals of Tyrannosaurus, the most well-known tyrannosaur species.

According to Darla Zelenitsky (associate professor of paleobiology at University of Calgary), the two groups of dinosaurs were very similar. However, carcharodontosaurs were more slim and light-built than heavyset tyrannosaurs.

Carcharodontosaurs weighed more than tyrannosaur dinosaurs, and reached weights of over 13,200 pounds (6,000 kilograms). Around 90 million to 80 millions years ago, the carcharodontosaurs vanished and the tyrannosaurs took over as the top predators in Asia.

Researchers noted that this is the first known carcharodontosaur dinosaur to be discovered in Central Asia.

Paleontologists knew that Timurlengia, a tyrannosaur, lived at the same place and time. However, at 13 feet (4m) in height and about 375 lbs (170 kg), Timurlengia was smaller than U. Uzbekistanensis. This suggests that U. Uzbekistanensis may have been the dominant predator in that area, eating up long-necked sauropods as well as ostrich-like dinoopreds.

(Dinosaur Valley Studios).

Above: Reconstruction of Ulughbegsaurus’s upper jaw and teeth.

"Our discovery suggests that carcharodontosaurs are still dominant predators of Asia 90 million years ago," Kohei Tanaka, a lead researcher at the Graduate School of Life and Environmental Sciences, at the University of Tsukuba, Japan, said to Live Science via email.

Peter Makovicky (a professor of paleontology from the University of Minnesota) agreed that U. Uzbekistanensis likely occupied the top of the local food chain.

Makovicky stated that the bone was so large that it would have made a predatory dinosaur, and most likely the apex predator of its ecosystem.

According to the team, the U. uzbekistanensis discovery is the last known occurrence in which a carcharodontosaur was found with a tyrannosaur before those dinosaurs went extinct.

U. uzbekistanensis' unique bony bumps were discovered above its teeth by the team. It also had bony ridges along its jaws that were very similar to Thanatotheristes, a 79.5 million-year old tyrannosaur whose name means "reaper death") from Canada.

Although it is not clear why these ridges are present in both species, Zelenitsky suggested that this could be a case where convergent evolution occurs, when closely related species evolve similar characteristics.

The study was published online in Royal Society Open Science on Wednesday, September 8.

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