Dinosaur Renaissance - Dinosaurs and The Origin of Birds

Dinosaurs and The Origin of Birds

For more details on this topic, see Origin of birds.

In the mid and latter parts of the nineteenth century, many scientists thought there was a close relationship between birds and dinosaurs—and that dinosaurs represented an intermediate stage between "reptiles" and birds.

It was 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 (fused clavicles). Thereafter, the accepted hypotheses was that birds evolved from 'crocodylomorph' and 'thecodont' ancestors, rather than dinosaurs. This removed dinosaurs from playing a central role in debates about the origin of living species, and may have contributed to the decline of academic interest in dinosaur evolution.

This remained the situation until 1964, when John Ostrom discovered a small carnivorous dinosaur which he named Deinonychus antirrhopus, a theropod whose skeletal resemblance to birds seemed unmistakable. This led Ostrom to argue that Huxley had been right, and that birds had indeed evolved from dinosaurs. Although it was Deinonychus that inspired Ostrom to connect birds with dinosaurs, very similar birdlike dinosaurs, such as Velociraptor had been known for many decades, but no connection had been made. After Ostrom's discoveries, the idea that birds evolved from dinosaurs gained support among palaeontologists, and today it is almost universally accepted. Newer methods, such as cladistics, and the discovery of several feathered dinosaurs have helped confirm the relationship.

The relationship between dinosaurs and birds has led to considerable interest in dinosaur — particularly theropod — phylogeny, which is now far better understood.