Original by Dr Margaret Rowe, 2002
Last revised by the Department of the Environment and Heritage, December 2004
ISBN 0 6425 4820 X
Did birds evolve from dinosaurs?
Biologists believe that birds evolved from dinosaurs.The earliest evidence of bird-like creatures is found in 150 million year-old fossils. Archaeopteryx was a crow-sized animal with teeth and a tail like a reptile, and feathers like a bird.
Figure 1 Archaeopteryx an ancient ancestor of modern birds
Birds have evolved along a great variety of pathways, becoming adapted to a wide range of habitats, diets and ways of life. For example, a variety of bill sizes and shapes adapt different birds to eating certain of types of food. Birds' legs and feet vary, suiting birds to perching, walking, running, climbing or swimming. The various wing shapes found among birds are suited to different styles of flight.
Gene technology is being used to compare the genetic make-up of groups of birds and to sort out their evolutionary relationships. Sometimes evidence from DNA brings into question the existing views about the relationships of groups of birds to each other. Some of the similarities in appearance are because the birds are adapted to similar surroundings and a similar way of life, and not because they are closely related. For example, many shorebirds have bands of colour across their chest, but may or may not be closely related.
How could these bands of colour across the chest help the birds survive? (Hint, read about "Colours, patterns and camouflage" in the section "The feather coat")