Chinese scientists have found a “intermediate” in the evolution of birds

Paleontologists have described a previously unknown species of primitive bird with an unusual anatomy of the skeleton and an unusual approach to fly.

Китайские ученые нашли «промежуточное звено» в эволюции птиц

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To say that humans evolved from primates, not exactly: we are primates. The same applies to birds — the most common class of higher vertebrates. Today there are over 18 thousand species, and they are not “evolved” from dinosaurs — they are dinosaurs, the representatives of the same ancient groups, many branches of which perished in the Cretaceous-Paleogene extinction about 65 million years ago.

Modern research in principle, does not allow to draw a clear line between “real birds” and ancient dinosaurs-the theropods, many of which had a similar skeleton, and feathers. On the other hand, some of the nuances of evolution, which gave the birds a modern look, remain poorly understood. An important gap in this evolutionary chain closes a new find of Chinese paleontologists.

In an article published in the journal Proceedings of the National Academy of Sciences, Zhou Zhonghe (Zhonghe Zhou) and his colleagues describe a previously unknown ancestor of birds that lived 127 million years ago, long before the extinction of dinosaurs. Discovery, scientists have attributed to one species and genus — Jinguofortis perplexus — and note that it existed just at the time when the ancestors of birds learned this flight.

In contrast, who lived about the same years of Archaeopteryx and other flying dinosaurs, the spine of this “bird” is not passed into a long tail. Instead, its tail vertebrae are shortened and fused, forming a single bone, such pygostyle, which serves as a support for the tail feathers the majority of modern birds (although within these powerful feathers J. perplexus, apparently, do not). The discovery was one of the earliest examples of birds with pygostyle — on a par with the ancient primitive confuciusornis.

Китайские ученые нашли «промежуточное звено» в эволюции птиц

The wingspan of the remains found Jinguofortis perplexus is estimated at 69.7 cm / ©Wang et al., 2018

Partially coalesced at J. perplexus and phalanges of third fingers, that has not been characteristic of other early ancestors of birds, but reflects the future trend is to simplify and change the skeleton in the course of a long adaptation to flight. However, his jaw kept the set small and sharp teeth, though found together with sample traces of the stones-gastroliths indicate that this ancient bird was feeding on vegetable food. Judging by the size and geometry of the wings, birds could dwell in dense forests.

Unusual was the anatomy of the shoulder girdle J. perplexus, whose bones have grown together even more than in modern birds. Proceeding from it, the authors believe that these flying animals are also slightly different. According to scientists, this illustrates new ideas about the evolution of flight in birds, which is not a long straight chain of changes, and mixed complex “search” for optimal solutions, the anatomical parts, mechanics and aerodynamics of flight.