According to the Institute of vertebrates and Paleoanthropology of the Chinese Academy of Sciences, the international research team led by researcher Xu Xing published the latest research results in the academic journal contemporary biology on the 24th: they found two new dinosaurs in China: bannykusulatensis and xiyunykuspeng, which gave scientists a deeper understanding of the mystery of Alvarez's "missing" finger.
Xu Xing explained that during the evolution of quadrupeds, the number of fingers or toes decreased many times. For example, the horse fossil series shows how horses evolved from multiple toes to one toe today. Interestingly, scientists have also found this situation in Alvarez Dinosaurs: Alvarez dinosaurs are theropods with extremely strange shapes. Their forelimbs are very short but very strong. Each forelimb has only a special big finger claw, but their skulls and hind limbs are similar to birds. These peculiar features make scientists extremely confused and controversial about the phylogenetic location, biogeographic evolution history and niche of this kind of dinosaurs.
The key to resolving the dispute is the early Alvarez fossils that have not been fully specialized. However, paleontologists have not found the intermediate type between the primitive group (living in the late Jurassic) and the progressive group (Late Cretaceous) of Alvarez fossils, and do not know how this change occurred.
The two dinosaurs reported by the scientists, the Western clawed dragon found in the Junggar basin of Xinjiang in 2005 and the half clawed dragon found in the northwest of Inner Mongolia Autonomous Region in 2009, just filled the 9000 year evolution gap of primitive groups and progressive groups.
Xu Xing said: "from the long grasping forelimb of the early Alvarez dragon close to the primitive theropods, to the half clawed dragon forelimb with long forelimbs and specialized claws, and then to the highly specialized single fingered forelimb with shortened function of the late Alvarez dragon, this transformation has lasted for nearly 50 million years in a gradual way."
The co-author, Dr. joanier of the University of Witwatersrand in South Africa, believes that this evolution may be related to changes in its food“ They have strong hands and large claws, but their jaws are very delicate, just like anteaters and anteaters in dinosaurs. "The early Alvarez dragon has typical carnivore teeth and hands more conducive to grasping prey. Only the late Alvarez dragon developed a huge single claw, which is likely to be used to dig and destroy rotten wood and ant nests, Eat ants or termites inside.
"These fossil records are the best display of the evolution of anatomical features." "Like other examples often mentioned in evolutionary biology, such as the 'horse fossil' sequence, this dinosaur shows how organisms in the evolutionary branch changed their niche over time, from carnivores to insectivores," said James Clark, co-author of the paper and professor of George Washington University in the United States
The fossil specimens of the two new dinosaurs were discovered and collected by a joint expedition led by Xu Xing, James Clark and Tan Lin, Professor of Longhao Institute of Geology and Paleontology in Inner Mongolia. Xu Xing said that in the past few decades, China has produced a number of the most important dinosaur fossil specimens“ Our international field research team has gained a lot in recent years and will continue to produce more results.