The scientific research on the origin of birds
Birds
The scientific research on the origin of birds within the large groups of species birds could have evolved from is quite vital. Currently, scientists have reached a consensus that modern birds are a group of maniraptoran theropod dinosaurs that started their existence during the Mesozoic Era. In the 19th century, there was a proposal of a close relationship between ancient dinosaurs and birds after the discovery of the primitive bird in Germany referred to Archaeopteryx. Many skeletal traits are shared between birds and non-avian dinosaurs. Also, more than 30 fossils of species of non-avian dinosaurs show that the ancient animals had feathers since preserved feathers have been collected.
There are even tiny dinosaurs, such as Microraptor and Anchiornis, which have long, vaned arm and leg feathers forming wings. The Jurassic basal avialan Pedopenna also shows these long foot feathers.
In 2009, Paleontologist Lawrence Witmer concluded that this evidence is ample to demonstrate that avian evolution went through a four-winged stage. Fossil indication also indicates that birds and dinosaurs shared features such as hollow, pneumatic bones, gastroliths in the digestive system, nest-building, and brooding behaviors. Although the origin of birds has historically been a disputative topic within evolutionary biology, only a few scientists still dispute the dinosaur close relationship and similarities with birds, suggesting descent from other types of archosaurian reptiles. Within the accord that supports dinosaurian ancestry, the exact ordering of evolutionary events that gave rise to the early birds within maniraptoran theropods is disputed.