The newly discovered jaw fossil of a new carnivorous dinosaur may contain the answers to an important piece of tyrannosaur evolution. Analysis of the fossil show that the animal, called Ulughbegsaurus uzbekistanensis, may have been the terror of the first tyrannosaurs.
Paleontologists found the fossil of the new dinosaur in the Bissekty Formation, in the deserts of Uzbekistan. The entire fossil, therefore, is just over 30 centimeters long and belonged to the upper part of the mouth of the U. uzbekistanensis. The new dino, moreover, belongs to the family of carcharodontosaurs – giant predators that lived on the planet shortly before the tyrannosaurs.
However, Carcharodontosaurs disappeared from the planet in the first half of the Cretaceous period, between 125 and 80 million years ago. Only then can the tyrannosaur family dominate the planet as top-of-the-line predators.
What the new research therefore indicates is that the new dinosaur lived together with older members of the tyrannosaur family. These tyrannosaurs, in turn, were small and primitive, still millions of years away from their descendants portrayed in Jurassic Park.
Thus, research published in The Royal Society journal reinforces the idea that carcharodontosaurs may have prevented the development of tyrannosaurs. According to carcharodontosaurs, such as the U. uzbekistanensis, therefore, disappeared 80 million years ago, tyrannosaurs could evolve giant and dominant species like the T. rex.
The life of tyrannosaurs from carcharodontosaurs in Central Asia
According to research estimates, the U. uzbekistanensis it lived 90-92 million years ago and was 8 meters long, reaching a ton. These estimates, as well as its complete habitat, however, are still not very clear, due to the lack of other fossils of the species.
The relevant fact is that 90 million years ago, tyrannosaurs already inhabited Uzbekistan and, according to the authors, this is the most recent evidence that both families of dinosaurs lived simultaneously. So far, the most recent fossils of this type have come from a formation in the United States, and belonged to a Carcharodontosaurus (Siats) and a tyrannosaurus (Moros) both 98 million years old.
As you can imagine, Central Asia was quite different almost 100 million years ago. The region was likely dominated by large coniferous forests and open plains. The main inhabitants, however, were sauropods (long-necked), hadrosaurs (with duck bills) and the two families of carnivores mentioned above.
It turns out that due to the size of the U. uzbekistanensis relative to the region’s tyrannosaurs, the new dinosaur was probably the dominant predator. Meanwhile, the tyrannosaurs of the time – the genus Timurlengia – barely more than 4 meters long and 170kg.
It is not yet known for sure, however, what caused the extinction of carcharodontosaurs. Still, the new research supports the hypothesis that these large hunters, who could weigh more than 6000kg in some species, prevented tyrannosaurs from developing as dominant predators.
Once Carcharodontosaurs dropped out of the picture, therefore, tyrannosaurs could populate the Earth, literally by the billions, until an asteroid caused the extinction of more than 90% of life on the planet.