Gerhard Heilmann discussed Beebe's Tetrapteryx hypothesis at considerable length in his 1926 book "The Origin of Birds". Heilmann examined hatchlings of many other bird species, both closely related to those studied by Beebe and belonging to more primitive species, in hope of finding additional evidence for the leg-wings which Beebe had documented. After failing to find such evidence, Heilmann ultimately rejected Beebe's Tetrapteryx hypothesis, and this remained the consensus among ornithologists for the next several decades. Beebe, however, continued to advance his Tetrapteryx hypothesis as late as the 1940s.