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Paleontologist Lawrence Witmer concluded in 2009 that this evidence is sufficient to demonstrate that avian evolution went through a four-winged stage. [2] Fossil evidence also demonstrates that birds and dinosaurs shared features such as hollow, pneumatized bones, gastroliths in the digestive system, nest-building, and brooding behaviors.
The evolution of birds began in the Jurassic Period, with the earliest birds derived from a clade of theropod dinosaurs named Paraves. [1] Birds are categorized as a biological class , Aves. For more than a century, the small theropod dinosaur Archaeopteryx lithographica from the Late Jurassic period was considered to have been the earliest bird.
The age of the dinosaurs never really ended—it only evolved. Birds (and their more reptilian cousins, the Crocodilia ) are the modern-day legacy of dinosaur’s 165-million-year-long stint on Earth.
These features make Archaeopteryx a clear candidate for a transitional fossil between dinosaurs and birds, [15] making it important in the study both of dinosaurs and of the origin of birds. The first complete specimen was announced in 1861, and ten more Archaeopteryx fossils have been found since then. Most of the eleven known fossils include ...
Birds evolved during the Jurassic Period from small feathered dinosaurs. The oldest-known bird, Archaeopteryx, dates to about 150 million years ago. With a mouthful of teeth and long bony tails ...
Researchers unearthed the skull of a previously unknown starling-sized bird species named Navaornis hestiae that was so well preserved they were able to digitally reconstruct its brain and inner ...
Each order of dinosaur has slightly differing pelvis bones providing evidence of common descent. Additionally, modern birds show a similarity to ancient saurischian pelvic structures indicating the evolution of birds from dinosaurs. This can also be seen in Figure 5c as the Aves branch off the Theropoda suborder.
The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds, have further evolved for swimming. The study of birds is called ornithology. Birds are feathered theropod dinosaurs and constitute the only known living dinosaurs.