Is it true that birds originated from dinosaurs?

Since He Xuli proposed that birds originated from dinosaurs, this hypothesis was once popular at the time, but at the same time, it was also opposed by some scientists. But the real impact on this hypothesis came in 1913. At that time, Professor Brom, a famous South African paleontologist, formally proposed a new hypothesis that birds originated from a molar tooth reptile called Pseudosuchus in detail.

The bigger impact came in 1926, when the famous Danish paleontologist Professor Heyman published a classic book on the evolution of birds - "The Origin of Birds". In this book, Professor Hyman strongly supports the hypothesis that birds originated from the telodonts. Due to the authoritativeness and strong influence of the book "The Origin of Birds", despite the objections of some scientists, almost all scientific papers and papers related to the origin of birds were published in the following nearly half a century. Textbooks regard the hypothesis of the origin of birds as molars as the final conclusion, while the hypothesis of the origin of birds as dinosaurs has almost been forgotten.

Pseudosuchus

It was not until 1970 that Galton proposed that birds and ornithischian dinosaurs were closely related, which set off a new wave of debate on the origin of birds. In 1972, British scientist Professor Walker proposed the hypothesis that birds and crocodiles are closely related. By 1973, Ostrom published a series of articles that resurrected Husslei's hypothesis that birds originated from theropod dinosaurs with convincing evidence and analysis.

Interestingly, less than 4 years after Galton proposed the hypothesis of the origin of ornithischian dinosaurs in birds, he resolutely gave up his view because he was convinced by Ostrom's theory of the origin of avian theropod dinosaurs. Ostrom was left with only two rivals: the traditional hypothesis of the origin of crocodiles and Volk's hypothesis of the origin of crocodiles. Supporters of these three schools were at odds with each other at the time, making the issue of the origin of birds a tripartite state in the paleontological community.

Coelurosaurus

What’s even more interesting is that Walker, the originator of the school that birds originated from crocodiles, announced in 1985 that after some thought, it was difficult to continue to maintain his original view because there was too little evidence. However, just when the followers of this school of thought were disappointed, Volker suddenly announced to his colleagues in 1991 that his theory of the origin of crocodiles could still be established, triggered by some unknown inspiration. However, before his followers could celebrate him, Walker once again made a move that surprised the world. He wrote to many of his colleagues in June 1992, again arguing that there was a lack of evidence for the crocodile origin hypothesis, and he apologized to his colleagues for being so inconsistent.

However, Volcker's followers did not completely defect with him. The most resolute position is Professor Martin, a paleontologist at the University of Kansas in the United States. He has published many papers continuously since 1979, relying on the comparison of the anatomical characteristics of the skulls of birds and crocodiles, and continues to insist that birds are crocodiles. Origin hypothesis.

pterosaur

In contrast, Ostrom's hypothesis that birds originated from theropod dinosaurs is mainly based on the similarities in the body bones of birds and coelurosaurs. But soon, Ostrom's followers also found new evidence from skull features that supported the hypothesis of the origin of theropod dinosaurs. Soon, Ostrom's view was supported by the vast majority of dinosaur experts. Dr. Gauthier, a paleontologist in California, cited a large number of advanced characteristics of theropod dinosaurs similar to birds to strongly support Ostrom's hypothesis. Gauthier believes that the evidence for the hypothesis of the origin of crocodiles is too scant compared to the hypothesis of the origin of theropod dinosaurs. Based on the principle of evolutionary parsimony, it can be concluded that the hypothesis of the origin of crocodiles is not valid. As for the theory of the origin of alveolar species, Gauthier believed that the alveolar species itself was not an independent natural group. It was just the basal group of archosaurs including pterosaurs, crocodiles and various dinosaurs. It is an artificial combination. To say that birds originated from the genus Odontosaurus is tantamount to saying that birds belong to the archosaurs, which is tantamount to saying nothing, because almost no one will doubt this. The question is, which naturally differentiated group among archosaurs are birds more closely related to? Are they dinosaurs, crocodiles, or some other group? Or, which specific type of dinosaur is it more closely related to? Only the answers to these questions are truly meaningful.

Archaeopteryx

However, at that time, the attacks on the hypothesis that birds originated from theropod dinosaurs did not weaken at all because of the growing momentum of this theory. The main reasons include: 1. Most of them were used by Ostrom to compare with The coelurosaurs that Archaeopteryx compared were either later than Archaeopteryx or about the same age. Opponents questioned, how could there be ancestral descendants between two types of animals so close in time? 2. Coelurosaurs themselves are already a relatively specialized group and therefore cannot be regarded as the ancestors of Archaeopteryx: 3. Although coelurosaurs and birds do have great similarities, these similarities may be the result of parallel evolution. In other words, it is entirely possible that they were obtained by evolving independently, so it does not indicate that there is any close relationship between them.

Millennium Chinese Bird Dragon

Although other ornithologists, represented by Fedo Hill of the University of North Carolina, also recognized the striking similarities between Archaeopteryx and dinosaurs, they believed that the flight skills of birds originated from arborealism. The theory of the origin of theropod dinosaurs believes that the flight skills of birds originated from a life of running on land, so it is also inclined to the hypothesis that birds originated from telodonts. They believe that because the troglodytes had not yet acquired the ability to walk on two legs, they were better adapted to life in the trees.

Unexpected Beipiao Dragon

However, no matter how long-lasting and fierce the debate is, because it coincides with the views of the phylogenetic classification school that has been popular in the paleontological community since the 1960s on many issues, the birds resurrected by Ostrom are derived from beasts. The hypothesis of foot-like dinosaurs has still achieved great success in the paleontological community, leading most scientists to believe that birds are the descendants of dinosaurs. Therefore, Dr. Clay Clifford, a paleontologist at the American Museum of Natural History, praised Ostrom for doing a great job as early as 1977; and in 1986, in recognition of Professor Ostrom's many years of research on dinosaurs and For his remarkable achievements in the fields of the origin of birds and other fields, the Academy of Sciences in Philadelphia awarded him a Hayden Medal at the annual meeting of vertebrate paleontology attended by about 400 scientists.

Sinosauropteryx

After entering the 1990s, a hairy dinosaur fossil named Sinosauropteryx was discovered in the Beipiao area of Liaoning Province, China, by the original researcher. It provided the scientific community with the first animal with feather-like derivatives on its skin imprints. Specimens of foot dinosaurs. Paleontologists believe that this feather-like derivative was a precursor to the formation of true feathers, and its discovery has reinvigorated the theory that birds originated from theropod dinosaurs. Soon afterwards, scientists from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences discovered a series of important fossil specimens in the western Liaoning region, especially the unexpected discoveries of Beipiaoosaurus and Millennium Sinornithosaurus, which made more and more scientists It is believed that birds originated from theropod dinosaurs.

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