Tyrannosaurus rex dinosaurs are one of the large carnivorous dinosaurs that have ever lived on Earth, and 130 million years ago, Tyrannosaurus rex has been considered the most primitive tyrannosaurus dinosaur, and the appearance of Tyrannosaurus rex marks the peak of the evolution of the Tyrannosaurus rex family. Tyrannosaurus rex, tyrannosaurus rex... These fierce and tough names alone make people shudder, not to mention the horror memories of the film "Jurassic Park". However, a team of researchers, including Chinese, American and Canadian scholars, recently discovered the "small" ancestors of tyrannosaurs and gave them a "beautiful" name, the multicolored crowned dragon.
The fossils of Guanlong found this time are found in Wucai Bay in the Junggar Basin in Xinjiang, China, and the geological era is about 160 million years ago. The discovery of Crowned Dragon advanced the exact fossil record of Tyrannosaurus dinosaurs by nearly 30 million years, replacing Tyrannosaurus as the most primitive Tyrannosaurus dinosaur. At the same time, the crested dragon fossil is also one of the best known preserved Jurassic osteozoosaurs. The study's lead, Dr. Xu Xing, a researcher at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, named the new species Guanlong Wucaii. Its genus name "Guanlong" indicates the characteristics of the dragon, with a crown on its head, and the species name "Wucaii" indicates its discovery site, Colorful Bay, which has colorful rocks.
The key to exploring the origins of birds
Bonyosaurs include many progressive predatory dinosaur taxa commonly found in the Cretaceous (142 million to 0.65 billion years ago), including tyrannosaurs. In recent years, the hypothesis that birds originated from plesiosaurs has been widely acknowledged. The study of osteozoratosaurs is therefore key to understanding the origin of birds, an important evolutionary biology proposition. In the past few decades, fossils found around the world have provided a lot of information for the evolution of reconstructed dinosaurs and birds, especially the long-feathered dinosaur fossils found in the early Cretaceous Rehe Group in western Liaoning, China in recent years, which provide direct evidence for the two most important characteristics of birds: the origin and evolution of feathers and flight. But since the earliest known birds, Archaeopteryx found in Germany, lived in the late Jurassic, the history of dinosaur-bird conversion occurred before the Late Jurassic, and the most direct evidence for this transformation should be preserved in the Jurassic strata.
While continuing to study the morphology, function and systematics of long-feathered dinosaur fossils, researchers began to focus on the study of Jurassic strata and buried fossils, and conducted a series of scientific investigations in the Gobi Desert region of the Junggar Basin in Xinjiang, China. The Gobi expedition finally had a breakthrough: it was the discovery of the world's earliest known tyrannosaur class, crowned dragons. The fossil consisted of two skeletons, which, through histological studies, can be determined to represent juvenile individuals of about 7 years old and adult individuals of 12 years old, respectively. The two skeletons were found in the same location, with adults stacked on top of young individuals. Based on the lithology surrounding the fossils and the state of preservation, it is speculated that juvenile individuals may be attracted to the silt pit by some dead animals, fall into the pit and die, and then adult individuals are also attracted to the pit and suffer the same fate.
The role of the crown is particularly interesting
Crowned dragons had a peculiar combination of features: on the one hand, crowned dragons had long forelimbs and developed half-moon wrist bones like other advanced plesiosaurs; on the other hand, some of the features of its belt resembled those of relatively primitive theropod dinosaurs. The most peculiar thing is that it has a huge, very delicate and fragile crest on its head. It might not be too strange if this crest had grown on the head of a plant-eating dinosaur, but it would have grown on a ferocious tyrannosaur, which is incomprehensible. Researchers speculate that the function of the crown may be to attract the opposite sex or to show off itself, like the brightly colored crown on a rooster's head. More interestingly, juvenile individuals have a significantly smaller crown than adult individuals, and it is speculated that the crown may still be an important sign of sexual maturity. The crown may also have other functions, such as sound, heat dissipation, and its specific function needs to be further studied and confirmed.
The discovery of The Crowned Dragon tells us that the Asian region was one of the most important regions for the early evolution of tyrannosaurs. In fact, many primitive tyrannosaurs have been found in other parts of the world, such as Eotyrannus, a primitive tyrannosaur with long forelimbs found in the early Cretaceous period. Some fragmented specimens found in the late Jurassic period may even represent the earliest tyrannosaurs. For example, Stokesosaurus found in North America and Aviatyrannis, the grandmother Tyrannosaurus in Europe, have some typical characteristics of tyrannosaurs, probably belonging to the original tyrannosaurs, but unfortunately too little fossil material has been preserved. In any case, these fossils suggest that by the time of the Late Jurassic Period, tyrannosaurs had been widely distributed in the Northern Hemisphere, beginning their flourishing history.
An important part of the evolution of tyrannosaurs
By analyzing these fossil records, one can speculate about the possible evolutionary history of tyrannosaurs. One possibility is that during the middle Of the Jurassic Period, tyrannosaurs originated in Asia. Early tyrannosaurs were small, with long forelimbs and feathers. Subsequently, they migrated to other regions, and although Asia may have begun to leave the Pancontinent at that time, the possibility of land bridges cannot be ruled out. Later tyrannosaurs gradually became larger, their forelimbs slowly shortened and smaller, and the feathers on the bodies of large tyrannosaurs even degenerated. There are real examples of changes in skin derivatives on the surface of the body in the animal kingdom, for example, elephants still have hair on the surface of the body in their infancy, and the hair gradually falls off and disappears after adulthood. According to the proportional effect of the organism, if the morphology of the organism is unchanged, its body surface area changes much faster than the length change rate, and its volume (or weight) changes much faster than the body surface area. Early tyrannosaurs, due to their relatively small individual size, had a relatively large surface area per unit volume, dissipated heat quickly, and required feathers to keep warm. By the late tyrannosaurs, the volume had developed greatly compared with their ancestors, and the feathers had gradually disappeared. Therefore, the change of tyrannosaur feathers from existence to absence also corresponds to the development process of tyrannosaur body size from small to large.
The evolution of the Tyrannosaurus family reached its peak at the end of the Cretaceous period, marked by the appearance of Tyrannosaurus rex. The Tyrannosaurus rex may have been able to become one of the largest carnivores in Earth's history because it adopted a new way of development: not only did it grow faster, but it also had a relatively longer period of rapid growth. This hypothesis about the evolutionary history of tyrannosaurs is only one of many hypotheses, but there are many other possible evolutionary histories. For example, it is possible that by the middle of the Jurassic period , tyrannosaurs were already widely distributed on Earth , and subsequently evolved independently or interacted with each other on various continents. In any case, the Asian region played an important role in the entire evolutionary history of Tyrannosaurus rexes. From the peculiar crowned dragons to the feathered tyrosaurus, from the little-known Alectrosaurus to the massive Tarbosaurus, the discovery of these genera reminds time and time again that Asian tyrannosaurs played an important role in the evolution of tyrannosaurs, and the evolutionary history of the tyrannosaur family has a strong Asian color.