Support for the theory that bird wings descended from dinosaurs that had digits 1, 2 and 3, is published in Nature Communications this week. This is contrary to previous studies which had suggested that bird wing digits arise in the embryo in digit positions 2, 3 and 4.
Bird wing anatomy resembles the digits on the hands of Triassic theropod dinosaurs, but which digit positions gave rise to those seen in modern birds is still unclear. To understand how digit patterns are generated, Matthew Towers and colleagues produce genetic maps of the chick wing to pinpoint areas of soft tissue and cartilage development. Their results are in agreement with the proposal that the digits of the bird wing are 1, 2 and 3 having evolved from theropod dinosaurs that had the same digits.