Phylum ChordateSubphylum Vertebrata

Class Aves: Birds

Class Aves: Birds Evolved from small, carnivorous dinosaurs

about 150 million years ago.Oldest known bird fossils belong to the

species named Archaeopteryx. Impressions of feathers and wishbone clearly

visible. Had several characteristics of its dinosaur ancestors, including teeth and claws on its forelimbs

Archaeopteryx

feathersfeathers

Wing claw

Class Aves: Birds Birds diversified after Archaeopteryx, a

process that accelerated when the dinosaurs were wiped out. Today, they number around 9,000 species.

Class Aves: Birds Are endothermic. Have a beak instead of teeth. Skeleton is adapted for flight– most of the

bones are thin walled and hollow.

Class Aves: BirdsLungs are

connected to several sets of air sacs, an arrangement that ensures that oxygen-rich air is always in the lungs.

Class Aves: BirdsHave a 4-chambered heart and double loop

circulation.

Class Aves: BirdsQuick and

efficient digestive system

Class Aves: BirdsLack a urinary bladder and excrete their

nitrogenous wastes as uric acid.Lay amniotic eggs encased in a hard, calcium-

containing shell.

Classification of Birds:Several orders including:1. Order Anseriformes: includes ducks, geese,

and swans; have a broad bill covered with a soft skin; webbing between toes; about 200 species.

Mallard duckAnas platyrhynchos

Classification of Birds:2. Order Falconiformes: includes vultures,

kites, hawks, condors, falcons, and eagles; all are diurnal predators with keen vision and sharp curved claws for capturing animals; more than 250 species.

Classification of Birds:3. Order Strigiformes: owls; nocturnal

predators with large eyes, external ears, and powerful beaks; about 145 species.

Great Horned Owl

Classification of Birds:4. Order Galliformes: ground birds including

grouse, chickens, pheasants, and quails; herbivorous; short beaks and feet well-adapted for running and scratching; about 250 species.

Classification of Birds:5. Order Charadriiformes: shore birds, or

waders, including gulls, terns, puffins, and plovers; usually live in colonies; strong fliers; over 300 species

Classification of Birds:6. Order Passeriformes: perching birds

including songbirds, such as mockingbirds and jays; largest bird order, consisting of 60% of all bird species (approx. 5,500 species).

Northern Mockingbird

Blue Jays

Food is stored and moistened

Secretes acid for breaking down food

Helps in mechanical breakdown of food

Nutrients are absorbed

Nitrogenous wastes and digestive waste accumulate before being dumped