Class Aves Birds are reptile like animals that maintain a constant internal body temperature. They have an outer covering of feathers, 2 legs that are covered with scales and front limbs modified into wings.

Characteristic that separates birds from other animals = feathers Most paleontologists think that birds evolved from extinct reptiles like dinosaurs. Part of the evidence: Archaeopteryx: First birdlike fossil discovered

Well developed feathers like a modern bird. Teeth, bony tail, Toes and claws on its wings like dinosaurs.

Body temperature control: Endotherms - ‘warm blooded’ – they control their Internal body temperature. Feathers help to insulate the body. Most birds internal temperature is about 41C (105.8F) even on cold days. Down – trap air to keep bird warm Contour – provide lifting, force and balance needed for flight

Feeding: Bird’s beaks or bills are adapted to the type of food they eat. Insect eating – fine, short beaks Seed eating – short, thick beaks Long, thin beaks – gather nectar Carnivores – strong, hooked beaks

No teeth – have specialized structures to help break down food. Crop – food is stored and moistened. Gizzard – In birds that eat insects and birds, help further digestion by grinding it. Usually small stones inside.

Respiration: Inhales – most of air first enters large air sacs in the body cavity and bones and then flows to the lungs. Air travels through the lungs in a series of small tubes where gas exchange takes place.

Circulation: 4 Chambered heart. Heart beats quickly – from 150 to more than 1000 beats per minute!

Excretion: Nitrogenous wastes are removed by the kidneys and converted into uric acid. Most water is reabsorbed and excretion is in a white pasty form (bird droppings) Response: Well developed brain that can interpret and respond to A lot of incoming signals. Well developed eyes – can see color well.

Movement: Flight less birds – walk, run Cassowary

Adaptations for flight: Most other birds fly. Adaptations for flight: Long bones are very strong (strengthened by internal struts) and light (air spaces) Large chest muscles Enlarged breast bone or sternum where muscles are attached to. Feathers

Internal fertilization Lay eggs – oviparous Reproduction: http://video.nationalgeographic.com/video/animals/birds-animals/ground-birds/weirdest-bowerbird/ Internal fertilization Lay eggs – oviparous Eggs have hard outer shells. Most birds incubate their eggs until they hatch. Both parents often provide food for their young.