BIRDS

EVOLUTION OF BIRDS

• Birds are thought to have evolved from a group of bipedal dinosaurs called theropods. The ancestor of birds was probably similar to theropod called Deinonychus which is presented by the sketch.

• Fossils of Deinonychus were the first identified in 1960s.This was an extremely important discovery. It finally convinced most scientist that birds had descended from dinosaurs, which had been debated for almost a century.

• Deinonychus is the genus name of an extinct dinosaur that is considered to be one of the closest non-bird relatives of modern birds. It lived about 110 million years ago in what is now North America.
  
• Theropods - a carnivorous dinosaur of a group whose members are typically bipedal and range from small and delicately built to very large.

THE ORIGIN OF BIRDS

• The discovery that birds evolved from carnivorous dinosaurs of the LATE JURASSIC was made possible by recently discovered fossils from China, South America, and other countries, as well as by looking at old museum specimens from new perspectives and with new methods.

• The hunt for the ancestors of living birds began with a specimen of Archaeopteryx, the first known bird, discovered in the early 1860s. Like birds, it had feathers along its arm and tail, but unlike living birds, it is also had teeth and a long bony tail. Futhermore, many of the bones in Archaepteryx hands, shoulder girdles, pelvis, and feet were distinct not fused and reduced as they are in living birds.

5 MAJOR CHARACTERISTICS OF BIRDS

FEATHERS- are the defining characteristic of Aves, found on every living species of bird and no other class of animal. 

• made of keratin, the same substance that forms hair and nails in other animals and are highly modified scales.
• feathers are critical not only for flight but also for warmth and protection against the elements and many species 
• feathers for males used to attract mates
  

WINGS- all birds have wing, although not all birds can fly. Nor are wings confined to Aves: bats are flying mammals and most insects have wings.

        

BEAK-all birds have beaks or bills, made of a bony core surrounded by a thin layer of keratin.

• Birds do not have true teeth, but many have species have tomia
• sharp ridges along the edge of their beaks
• birds do not chew food
• grind or rip into pieces small enough to swallow
• shape of birds beak indicates the birds general diet
• meat eaters like hawks and owls have sharp, hooked beaks for ripping and tearing
• strong cone-shapes beaks help seed eaters break through shells.
• ducks and geese have broad,flat beaks for straining food out of water
  

EGG-all birds lay eggs,some very colorful or covered with spots.Eggs are not unique to eggs,of course fish,reptiles,amphibians and insects also lay eggs.

SKELETON-most birds have lightweight skeleton with hollow bones.

• keeps them light enough for flight
• fused bones including the collarbones or wishbones make birds skeleton rigid
• sternums or breastbones are large,providing sturdy attachment points for powerful wing muscles
  

DIVERSITY OF MODERN BIRDS

BIRDS are one of the most recognizable and diverse group of modern vertebrates.Over the past two decades, a wealth of new fossil discoveries and phylo genetic and macro evolutionary studies has transformed our understanding of how birds originated and became so successful.

The phylogeny shows where birds fit into the larger vertebrate family tree and the relationships of the earliest birds and their closest dinosaurian relatives (based on and other studies cited therein)