منابع مشابه
Archaeopteryx feathers and bone chemistry fully revealed via synchrotron imaging.
Evolution of flight in maniraptoran dinosaurs is marked by the acquisition of distinct avian characters, such as feathers, as seen in Archaeopteryx from the Solnhofen limestone. These rare fossils were pivotal in confirming the dinosauria-avian lineage. One of the key derived avian characters is the possession of feathers, details of which were remarkably preserved in the Lagerstätte environmen...
متن کاملReassessment of the Wing Feathers of Archaeopteryx lithographica Suggests No Robust Evidence for the Presence of Elongated Dorsal Wing Coverts
Recently it was proposed that the primary feathers of Archaeopteryx lithographica (HMN1880) were overlaid by long covert feathers, and that a multilayered feathered wing was a feature of early fossils with feathered forelimbs. The proposed long covert feathers of Archaeopteryx were previously interpreted as dorsally displaced remiges or a second set of impressions made by the wing. The followin...
متن کاملLikelihood reinstates Archaeopteryx as a primitive bird.
The widespread view that Archaeopteryx was a primitive (basal) bird has been recently challenged by a comprehensive phylogenetic analysis that placed Archaeopteryx with deinonychosaurian theropods. The new phylogeny suggested that typical bird flight (powered by the front limbs only) either evolved at least twice, or was lost/modified in some deinonychosaurs. However, this parsimony-based resul...
متن کاملDefining fraudulent essential medicines
Many of the flows described in this study can affect grandscale geopolitical events. Cocaine trafficking has fed instability in Guinea-Bissau; firearms trafficking has fueled a rebellion in northern Mali; maritime piracy threatens to undermine commerce in the Gulf of Guinea. These flows demonstrate that transnational organized crime has truly risen to the level of a security threat in West Africa.
متن کاملPrimitive Wing Feather Arrangement in Archaeopteryx lithographica and Anchiornis huxleyi
In modern birds (Neornithes), the wing is composed of a layer of long, asymmetrical flight feathers overlain by short covert feathers. It has generally been assumed that wing feathers in the Jurassic bird Archaeopteryx and Cretaceous feathered dinosaurs had the same arrangement. Here, we redescribe the wings of the archaic bird Archaeopteryx lithographica and the dinosaur Anchiornis huxleyi and...
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ژورنال
عنوان ژورنال: Nature
سال: 1985
ISSN: 0028-0836,1476-4687
DOI: 10.1038/314210b0