Tracing the Evolution of Avian Wing Digits
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چکیده
منابع مشابه
Tracing the Evolution of Avian Wing Digits
It is widely accepted that birds are a subgroup of dinosaurs, but there is an apparent conflict: modern birds have been thought to possess only the middle three fingers (digits II-III-IV) of an idealized five-digit tetrapod hand based on embryological data, but their Mesozoic tetanuran dinosaur ancestors are considered to have the first three digits (I-II-III) based on fossil evidence. How coul...
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Half a billion years ago, the first fourlegged land animal crawled out of the sea onto dry land. How did the limbs that creature crawled on evolve from the fins of its fishy ancestors? This question has long intrigued biologists. Fossil records suggest that tetrapod legs evolved step by step from fins, and comparative gene expression studies have provided some insights into how mutation and nat...
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The identities of the digits of the avian forelimb are disputed. Whereas paleontological findings support the position that the digits correspond to digits one, two, and three, embryological evidence points to digit two, three, and four identities. By using transplantation and cell-labeling experiments, we found that the posteriormost digit in the wing does not correspond to digit four in the h...
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ژورنال
عنوان ژورنال: Current Biology
سال: 2013
ISSN: 0960-9822
DOI: 10.1016/j.cub.2013.04.071