Dinosaur renaissance "reptiles" and birds. Shortly after the 1859 publication of Charles Darwin's "The Origin of Species", British biologist and evolution-defender Thomas Henry Huxley proposed that birds were descendants of dinosaurs. He cited skeletal similarities, particularly among dinosaurs, the "first bird"—"Archaeopteryx"—and modern birds. However, in 1926, Gerhard Heilmann wrote his influential book "The Origin of Birds", in which he dismissed the dinosaur–bird link, based on the dinosaurs' supposed lack of a furcula. Thereafter, the accepted hypothesis was that birds evolved from crocodylomorph and thecodont ancestors, rather than from dinosaurs. This removed dinosaurs from a central role in debates about the origin of
Specimens of Archaeopteryx "Archaeopteryx" likely indicated it had very little flight ability. The furcula (wishbone) is well-preserved and lies between the scapulae; its boomerang-like shape reveals a 75-degree angle between its branches. De Beer identified a compressed mass of bone as a sternum in the London specimen, but later researchers disputed this as more likely to be a concretion of vertebrae encrusted by calcite. That "Archaeopteryx" lacked a bony sternum is in agreement with the modern consensus that many specimens of "Archaeopteryx", including the London, likely represented immature animals whose sterna were still cartilaginous. The pelvic girdle is separated into its three components