We often hear people say that modern birds evolved from some dinosaurs. Apart from both being reptiles, what evidence have paleontologist discovered that validates this claim?
A small bird-like dinosaur, called the
archaeopteryx (left), lived in what is now southern Germany about 150 million years ago. About the size of a crow, it had a shortened tail, long hands, a perching toe slightly turned backward, and wing feathers that were adapted for flight. This creature has long been considered the most ancient bird known. However, despite its birdlike characteristics, its body more closely resembled those of small meat-eating dinosaurs than those of more birdlike dinosaurs. Many paleontologists identify the archaeopteryx as the so-called missing link between early reptiles and modern birds.
Preserved within lake deposits in northeastern China dating to 125 million years ago are skeletons of small dinosaurs covered with hair-like filaments and/or feathers unsuited for flight. With them are found the remains of numerous small and medium-sized birds that obviously could fly. Remains of birdlike dinosaurs also occur in sediments deposited from 85 million to 65 million years ago in Asia, North America, and South America. All of these bird-like dinosaurs are included within a group of meat-eating dinosaurs called
coelurosaurs (above). Although these animals occur too late in time to have been ancestral to birds, their skeletal anatomy suggests that they were closely related to the archaeopteryx.
The similarities between the archaeopteryx and the coelurosaurs strongly suggest that birds evolved from dinosaurs.
