Wednesday, June 16, 2010

Early Birds

There are a number of flying creatures of the early Cretaceous that are recognized as birds:
"Sapeornis[1] is a genus of primitive bird which lived during the Early Cretaceous (late Aptian to early Albian, roughly 120-110 mya). The genus contains only the species Sapeornis chaoyangensis which is known from fossils found in Jiufotang Formation rocks near Chaoyang, PRC. Several nearly complete skeletons have been found (Zhou & Zhang 2003)."
"Omnivoropteryx (meaning "omnivorous wing") is a genus of primitive flying bird from the early Cretaceous Upper Jiufotang Formation of China. The authors who described Omnivoropteryx, Stephen Czerkas and Qiang Ji, stated that their specimen closely resembles Sapeornis, but the pubis was longer and, since no skull was known for Sapeornis, they did not consider the two names synonyms.[1] The later discovery of Sapeornis skulls shows that they were indeed similar to Omnivoropteryx. This may make Omnivoropteryx a junior synonym of Sapeornis, and the name may be abandoned.[2]"
A preliminary report on a new bird, Omnivoropteryx sinousaorum, from the Upper Jiufutang Formation (Early Cretaceous) of Liaoning, China. This new bird has a skull which most closely resembles that of Caudipteryx, but its body has proportionately long forelimbs indicating a strong ability to fly and comparatively short hindlimbs with feet that were strongly adapted for perching. The highly derived avian characteristics of the wings and hindlimbs, together with the unique morphology of the skull reveal that Omnivoropteryx had adapted to a different dietary ecological niche from that of predaceous birds. This demonstrates that a far greater diversity of birds co-existed during the Late Jurassic/Early Cretaceous than has been previously known. In addition to variations in behavior, the anatomical differences also present a broader understanding which has significant implications towards the phylogenetic relationships during the early stages of avian evolution."

"Described below are two such dromaeosaurs [Scansoriopteryx and Cryptovolans], but preserved with impressions of primary flight feathers extending from the manus which demonstrate an undeniable correlation towards the ability to fly. This compelling evidence refutes the popular interpretation of birds evolving from dinosaurs by revealing that dromaeosaurs were already birds and not the non-avian theropod dinosaurs as previously believed"

"Confuciusornis is a genus of primitive crow-sized birds from the Early Cretaceous Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago. Like modern birds, Confuciusornis had a toothless beak, but close relatives of modern birds such as Hesperornis and Ichthyornis were toothed, indicating that the loss of teeth occurred convergently in Confuciusornis and living birds. It is the oldest known bird to have a beak.[1]"
Note that the dino-to-bird explanation falls back on the idea of "convergence" to fill in the holes of the theory.

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