Feathered Dinosaurs and Birds
Only few people know that the theory that birds evolved from dinosaurs is nearly as old as dinosaur paleontology itself. It goes back to the same period Darwin was beginning to propose his theory of evolution. Darwin wasn't immediately liked. If fact one of his advocate was Thomas Henry Huxley, a 20-something year old self-taught anatomist and biologist. Normally such a person wouldn't take up much attention or time from the intellectual elite at the time but there was something about this young lad that attracted Darwin to him. He wished to persuade him that they theory of evolution wasn't just hot air and that's what he did. In a few years Huxley went from an ardent disbeliever to an advocate of Darwin's theory. In Darwin's late years, Huxley took on the challenge to demonstrate to the world the advancements of science and evolutionary theory. He was the first to name himself Darwin's Bulldog.
During this period he was also occupied in his own studies and was becoming proficient in reptilian fossils. A strange fossil was found in 1861 that was called Archaeopteryx. It was 145 million years old and looks like a very primitive bird with flight feathers and wings. However it was strange, its head and its skeleton looked more like a lizard than a bird. It had rows of sharp teeth where a beak should have been and has three claws on its wings and back feet that corresponded to dinosaurs more than birds. Huxley took this to denote that small carnivorous dinosaurs had evolved to become birds. He had his believers and supporters at the time but the theory had fallen out of favor through time. Modern paleontologists frequently avoided the topic, not able to justify why a lizard would possess flight feathers. There weren’t any other fossils found with more primitive feathers or other links on this evolutionary chain. Paleontologists regarded it an evolutionary dead end and not the ancestors of birds.
But beginning in 1994, a series of findings were made in China by farmers. They uncovered a treasure trove of feather dinosaur and primitive bird fossils that dated between 120 to 145 million years ago. They were the first to find not only a single missing link but dozens, demonstrating a clear picture and establishing theropods were indeed bird ancestors.
The first of the feathered dinosaurs puzzled modern paleontologists. It was named Sinosauropteryx prima and it looks entirely like a theropod dinosaur with one exception, it was covered up in hair-like feathers. Paleontologists gathered together and theorized that feathers evolved to keep them warm and protected from the elements.
Then Sinornithosaurus was found. It was another dinosaur covered in feather but it had a little more. It had stiff feathers on its arms not unlike flight feathers but not enough to actually help in flight or gliding. These could have evolved for ornamentation to draw a mate or to keep balance while catching prey. These had long arms used for snatching prey and drawing them nearer to their dreadful teeth.
Just as the paleontologists were beginning to get worried their disbelief was wrong more fossils were discovered. This time they were like archaeopteryx with flight feathers and covered bodies some had lost the lizard-like tail and developed beaks. It was theorized these earliest of birds were gliders who were found in trees and caught prey far above the ground. However when biologists began to study bird flight from various angles they observed something strange. Birds in flight not flap their wings up and down as most have hypothesized. Instead they constructed a strange figure eight-like movement with their wings, as if they were swimming through the air. It was not long before paleontologists understood this would have been the same movement a theropod would make if it were grasping prey with its long arms and fierce claws. Flight seems something of a happy accident.