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Paleontology : The mystery of the Down-dinosaur

feathers arose in the course of Evolution, probably sooner than previously thought. This is an international team of researchers reported after a detailed study of two well-preserved pterosaurs from China in the journal "Nature, Ecology & Evolution". They noted that the body of the pterodactyl is covered with attachments, the springs in the Form and structure strongly resemble. Probably they were used for, among other things, the thermal regulation and the perception and improved the aerodynamics of the pterosaur.

First flight-capable Vertebrates

pterosaurs, scientifically pterosaurs were the first vertebrates that were able to fly thanks to their flight skins active. However, they are not ancestors of modern birds, which have developed according to most experts from theropod dinosaurs - two - legged-dinosaurs continue to move. On some fossils of pterodactyls, researchers had already found the thread - shaped, hair-or feather-like structures, so-called Pycnofasern. How they came to be and especially, how they are to interpret, is currently in dispute. Many experts believe that these primitive animals were part of a fleece-like hair, but no feathers.

The researchers Zixiao Yang of Nanjing University (Nanjing/China) investigated two pterosaurs, which lived in front of 165 to 160 million years ago in present-day China. On the body of the animals, the scientists found that in the case of high-resolution microscopic studies of four different types of Pycnofasern. A variant was composed of straight, unbranched structures that resemble hair. Others were branched at the end, or - as down feathers over the entire length. Such a spring variants are also of the same time living dinosaurs known. The Pycnofasern the pterosaurs were, therefore, also feathers, the researchers write.

This confirmed, therefore, also a computer analysis of the evolutionary history. "In spite of careful search, we could find no anatomical evidence that the four Pycnofasern differ in any way from the feathers of birds or dinosaurs," concludes study leader Mike Benton of the University of Bristol (Bristol/UK).

spring as the origin of a characteristic or multiple development?

the chemical structure of the filaments, spring-typical features. The researchers discovered cell structures called melanosomes, which contain color pigments. This could have given the fluffy feathers of a reddish color. Taken together, their study suggested that the feathers are already used to, in the case of the common ancestors of dinosaurs and pterodactyls. Alternatively, you could have developed in both lines independently of each other.

The spring variants were represented in different regions of the body vary greatly, and have probably had other functions, write the researchers. The body and wings occurring variants could, however, reduce the tensile forces and the Streamlining of the animals while flying have improved, similar to today's bats. Those spring variants, which were in high numbers, especially around the neck, shoulders, behind the legs and on the tail, support, possibly, as a sub-coat is the Regulation of the body temperature.

Wait for the better microscope

The big question is whether the investigated filaments are actually branched, writes Liliana D'alba of the University of Ghent (Belgium) in a comment on the study. The branch was the most important distinguishing feature of feathers to other formations of the skin. Although the fossils are exceptionally well preserved, the Interpretation of the filaments is always a bit subjective. In order to clarify this question, it is likely in the near future, better methods are available, for example special scanning electron microscopes. (dpa)

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