Feathered dinosaur

Only in the 1990s, the fossil record in the line of development of the theropod dinosaurs to birds was enriched by a number of finds of feathered dinosaurs and early birds in the People's Republic of China. Since the first discovery of Archaeopteryx in the Solnhofen limestone in 1861 it is also true that birds are descended from reptiles. However, other fossils that demonstrate this development were, until a few years extremely rare.

The Archaeopteryx is a mosaic of both features of the dinosaurs and the birds dar. The dinosaur features include about the long tail, the dinosaur -like chest belts, toothed jaw or even the abdominal ribs. Birds are typical especially the wings with the feathers, but also the legs with a special joint, the intertarsal, in the tarsus. This feature structure hardened the assumption about the origin of birds from dinosaurs and hence a key piece of evidence for the then just three years old evolution theory of Charles Darwin dar. Archaeopteryx, however, remained the only animal that represented a link between birds and dinosaurs and so were many theories, particularly on the development of flight and the specially constructed springs, unproven.

Archaeopteryx had feathers, the feathers of today's birds corresponded in structure and function. These so-called contour feathers consist of a central shaft, depart from the smaller side branches. These knots are interlocked with each other and get in this way stability. In addition, they are asymmetric and, together with adjacent springs an airfoil, which is permeable to air and impermeable to air off the tee at impact. Since the wing of Archaeopteryx were constructed, there is now a broad consensus on the flight ability of this ancient bird. How and whether these feathers could have evolved from reptilian scales, previously proved only a matter of speculation. See also: Evolution of bird feather.

1996 met with researchers in the sediments of the Jehol Group in the Chinese province of Liaoning on a fossil, which should constitute the beginning of a series of spectacular finds. This dinosaur fossil, a theropod named Sinosauropteryx, had a contour of filamentous structures. Even later fossils of the same region as Caudipteryx, Sinornithosaurus and particularly Beipiaosaurus showed similar körperumhüllende fibers which later turned out to as down-like structures of several filaments with a common point of origin. In addition, also found especially on the front legs and tail elements with a central shaft and symmetrically arranged side branches. A stiffening lacked these springs, however. Accordingly, they were not used as flight instruments, they were probably more the heat insulation of the body. Based on findings from the Oviraptor in an unambiguous position on a brood nest was already known that this dinosaur group must have been warm-blooded. An insulating layer spring confirms this assumption.

Thus, the evolution of feathers and bird flight is not fully understood, the gaps are, however, become much smaller than they were before 1996. But even in understanding the further evolution of birds to the modern representatives of the Chinese fossils have something to offer. In early 2001 it was reported by the discovery of a fossil bird named Apsaravis in the journal Nature. Since the discovery of the 1870 Ichthyornis not so close relative of extant birds more has been found.

Dissenting opinions

Some American Paläornithologen like Alan Feduccia interpret the relationships between birds and dinosaurs notwithstanding; they think that the birds had split off before the dinosaurs of the archosaurs.

So Archaeopteryx had 150 million years ago already had contour feathers like modern birds, some much later species of theropods as Caudipteryx or Protarchaeopteryx held for ancestors of birds, but would have been much more primitive feathers. This is better explained by the fact that these alleged descendants of theropod dinosaurs that have become flightless birds are what they coin the term " non- bird dinosaurs ".

Their study from the year 2005 comes to the conclusion that it was at the körperumhüllenden fibers which have some of the theropod found in Jeholgruppe, not feathers, but the connective tissue in the form of collagen fibers.

Finally, they argue that the fingers of theropods evolved from the fingers I-III, with the birds, this would but developed from the fingers II -IV.

The majority of paleontologists disagrees Feduccias but.