Tyrannosaurus, the largest and strongest carnivorous dinosaur in history, is probably the most popular person in the world of paleontology. It is also familiar in museums and movies. However, it is said that it was the last 20 million years of the Cretaceous that lasted 80 million years until the extinction of the dinosaurs 66 million years ago. Before that, the large carnivorous dinosaur at the top of the ecosystem was the unfamiliar “Carcharodontosaurus.” It is a mystery why and how the alternation occurred.
In these circumstances, international research groups such as the University of Tsukuba and the University of Hokkaido have discovered that the fossils found in the Upper Cretaceous strata of Central Asia and Uzbekistan are new species of Carcharodontosaurus. In the strata of the same time, a small companion tyrannosaurus was also found, the newest in the world and the first evidence of coexistence between the two in Asia. Researchers are excited to get puzzle pieces that get closer to the mystery of the alternation drama.
Former Champion Carcharodontosaurus
The research group examined unexplained fossils from the National Geological Museum in Tashkent, the capital of Uzbekistan. Maxilla (bone from cheek to nose) with a length of 24 cm and a height of 13 cm found in the stratum 92 to 90 million years ago, which corresponds to the Late Cretaceous (100 to 66 million years ago) in the country. It is something that can be done. As a result, the fossil was identified as a new species, as other discovered dinosaurs do not have the distinctive surface features of humps, wrinkles, depressions, and holes. In addition, the phylogenetic relationship with known species was analyzed and it was found to be a member of Carcharodontosaurus.
Carcharodontosaurus has a maximum length of 13 meters. It thrived from the late Jurassic (200-145 million years ago) to the mid-Upper Cretaceous and reigned at the top of the ecosystem. Meanwhile, the Tyrannosaurus family appeared in the Middle Jurassic and were initially small and for a long time overwhelmed by large dinosaurs. However, when Carcharodontosaurus companions disappeared from the Northern Hemisphere, they grew larger and prospered.
The research group named the new species “Ulughbegsaurus Uzbekistanensis”. The meaning is “Ulugh Beg lizard from Uzbekistan”. Ulugh Beg was a 15th-century mathematician and astronomer who also became a Timurid monarch.
Based on the related species discovered, it appears that the main bone was between 7.5 and 8 meters long and weighed more than 1 ton. “It has become the largest carnivorous dinosaur ever found in Uzbekistan,” explains Kohei Tanaka, assistant professor of life and environment at the University of Tsukuba (Paleovertebrate Paleontology).
“Mysterious white space” to reduce development
This Ulughbegsaurus. In addition to the importance of discovering new species, the research group considers it to be of significant value in many ways. One is that Carcharodontosaurus, which had been identified in the United States, Europe, and the eastern part of the Asian continent in the northern hemisphere, was also found in the westernmost part of the Asian continent at that time.
Second, it was first discovered in the Upper Cretaceous outside of North America that a Tyrannosaurus pair had already been found in the same stratum and coexisted with a Carcharodontosaurus pair. The member of this Tyrannosaurus is “Timrengia”, which is only 3-4 meters long and weighs 170 kg. Ulughbegsaurus, with its much larger body, must have reigned at the top of the ecosystem. In Uzbekistan, as in North America, the Tyrannosaurus family was small and the large Carcharodontosaurus family overwhelmingly coexisted. This is likely a clue to the mystery of the supremacy shift drama in future research.
It is also extremely important that the coexistence of both becomes the most recent record in the world. The record of coexistence in North America is 96 to 94 million years. This time, I updated this for about 2 to 6 million years. The Tyrannosaurus family was able to grow in size after 92 to 90 million years before the discovery of the great Ulughbegsaurus.
A large companion to Tyrannosaurus has been found in North America for 84 million years. Roughly 10 million years before that, it was a “blank mystery period” with no clues anywhere in the world. The discovery of Ulughbegsaurus was a worthwhile achievement in reducing this gap.
Assistant Professor Tanaka said: “It seems that there was a competition between huge carnivorous dinosaurs in the Cretaceous period, but fossils from the time when the largest Tyrannosaurus ‘unified the world’ were rare until now, and this time Ulughbegsaurus has haunted it. it was a test to complete. ”
The research group consists of Assistant Professor Tanaka from the University of Tsukuba, Professor Yoshitsugu Kobayashi from the Hokkaido University Museum, researchers from the University of Calgary, Canada, and the National Geological Museum of Uzbekistan. The results were published in the Royal Society scientific journal “Open Science” on the 8th.
Alternative drama, why it happened
The research group aims to elucidate the competition and evolution of the state of carnivorous dinosaurs and will continue to conduct research mainly in Asia. Especially in Uzbekistan, research is still limited, and even bigger discoveries can be expected.
Regarding the drama of the change of supremacy of Carcharodontosaurus and Tyrannosaurus, Assistant Professor Tanaka said: “I am currently looking for fossils and I am investigating in what order and at what time the position change occurred. I want to fill in the blank little by little. ”
The history of living things that was born about 4 billion years ago is a series of changes in supremacy. The case in which Carcharodontosaurus handed over the throne to the strongest animal in history, the Tyrannosaurus, is probably one of the most important events. I would like to pay attention to solving the mystery of the history of the rise and fall. At the same time, personally, I suddenly had a fantasy in my mind: “Will a creature that has hegemony appear alongside humans? What kind of alternation drama will it be and what kind of creature will it be?”