Jeholornis

Fossil plate with Jeholornis sinensis

• Dapingfang in Chaoyang City, Liaoning, China Jiufotang formation of the Jehol Group

• Jeholornis prima

Jeholornis (or Shenzhouraptor ) was a primitive bird species whose fossils were in the Cretaceous Jehol Group, one known as a fossil reservoir rock sequence in northeast China's Liaoning province discovered. The nomenclature of the taxon is controversial, as two scientific descriptions were published almost simultaneously, which designate the same taxon in different ways.

In addition to Archaeopteryx and Rahonavis Jeholornis one of the few original members near the group of birds that had a long bony tail with no sign of Pygostyls. With up to 27 caudal vertebrae of the tail was even longer than that of all known specimens of Archaeopteryx, whose tail consisted of a maximum of 23 vertebrae. Zhou and Zhang (2003) assume that the ancestor of all birds also had at least 27 members of tail. Jeholornis ' tail spine is like in another property that dromaeosaurider Deinonychosaurier, a bird-like theropod group of dinosaurs: The vertebral bodies were enclosed by prolonged lateral and ventral spinous processes, which ensured a stiffening of the tail.

On the other hand Jeholornis compared to the geologically older Archaeopteryx a total of more modern anatomy. In contrast to the very strong dentition of prehistoric bird Jeholornis had only three very small teeth in the lower jaw. Probably in adaptation to feeding on seeds of both upper as well as lower jaws are shorter and more robust. In the expression of the pelvic spine ( sacrum ) takes Jeholornis an intermediate position between Archaeopteryx and the higher birds a: Comparison of the five unfused pelvic vertebrae ( Sakralia ) which form the sacrum of Archaeopteryx, and the seven or more fused together pelvic vertebrae in more advanced birds such as Conficiusornis had Jeholornis six sacral vertebra, which were fused together.

In contrast to Archaeopteryx, which probably lacked a bony sternum, the sternum of Jeholornis acts advanced: It was elongated and equipped with perforated lateral trabecular projections. Jeholornis was better than the first bird to the flapping flight adapted: The shoulder joint pit was more attention upward oriented, extended the raven legs strut-like and the metacarpals I and II to the body merged into a Carpometacarpus. For a better flight ability also speaks the ratio between the lengths of the front and hind limbs, which had shifted more in favor of Jeholornis forelimbs. Jeholornis ' hand, however, was smaller and more robust than that of Archaeopteryx.

In two instances Jeholornis also marks the tail feathers have been handed down - similar to the feathered theropods Microraptor Caudipteryx and the tail ends in a fan of feathers. Footprints of the wings are also obtained; they demonstrate that Jeholornis possessed the necessary active flyer asymmetric flight feathers.

As with Archaeopteryx and a number of theropod dinosaurs show many invertebrates of Jeholornis pneumatic foramina, showing that already the ancestor of birds is a complex respiratory system had - apparently lay with the lungs associated air bags in front, whose protuberances ( diverticula ), among others, the vertebrae and other bone fill ( pneumatized ). In addition at Jeholornis the evolutionarily earliest indication of a clavicle air bag - the holes in the sternum records set its presence near.

Jeholornis is one of the few Mesozoic birds for whose diet there is a direct proof: In the abdominal cavity of a specimen numerous copies are round to oval to recognize plant seeds. The traditional fossil stomach contents has Jeholornis out in accordance with the beak morphology and seed-eating bird.