Hi, I'm Aubrey for about.com, today I'm going to go over a few of the characteristics that distinguish birds from other animal groups information from animals.about.com.Scientists commonly believe that birds evolved from reptiles 150 million years ago. Birds are vertebrates who lay eggs, have four-chambered hearts, lightweight bones, and wings.Let's take a closer look at a few of the traits that set birds apart from other animals.Feathers: Birds are the only group of animals that have feathers. Feathers are primarily comprised of the protein keratin. It is commonly known that feathers help birds fly. They also offer protection and warmth, helping birds to regulate their temperature.Bills: Birds don't have teeth. Instead they have bills, or mandibles that are covered with a thin, hard layer of keratin.Wishbone: Another distinctive characteristic of bird group is the furcula or "wishbone." The furcula is a bone with a forked shape that is located in the bird's chest, it came about from the fusion of the bird's clavicles. The wishbone helps the bird's respiration, and it strengthens the skeletal area of the birds chest during flight.In addition to these unique characteristic, birds also have a few defining qualities that they share with other vertebrates.Warm-blooded: For example, birds are warm-blooded or endothermic. They maintain a consistent body temperature regardless of the temperature of their environment.Light Weight Bones: Birds also have light weight bones.Four-Chambered Heart: Birds, like mammals, have four-chambered hearts. The efficient, four-chambered heart keeps deoxygenated and oxygenated blood separate. This helps birds to regulate their body temperature, it increases their metabolisms. and helps to support their muscular activity.Eggs: Birds reproduce by laying nutrient rich eggs.Communication: They also have a remarkable ability to communicate through calls and more complex songs.Thank you for watching, for more information on birds or other animal groups, go to: education.about.com.