- Birds evolved from reptiles and Archaeopteryx possessed both reptilian and avian features. Key avian traits include feathers, hollow lightweight bones, beaks, endothermy, and amniotic eggs. - Birds have highly specialized organ systems for flight including strong heart and respiratory systems. Their feathers provide insulation and flight abilities. - There are many orders of birds with varied traits like waterfowl that are aquatic, owls with keen vision and hearing, and songbirds that communicate through song.

1. Birds
Damnjanović Ivana

2. Evolution and Classification
• Birds are Vertebrates
of the Class Aves.
• The evolution of
warm-blooded, has
enabled birds to
survive in virtually
every known
environment.

3. Origin and Early Evolution
• Evidence from fossils
and from studies of
comparative
anatomy indicates
that birds evolved
from reptiles.
• Their features and
their fragile hollow
bones do not
preserve well.

5. Archaeopteryx
• The fossil genus
Archaeopteryx possessed
characters of both reptiles
and birds.
• Like reptiles it had a large
skull with teeth, bones that
weren’t hollow, claws on its
forelimbs, and a long tail.
• Its strong legs and rounded
wings indicated that it
glided rather than flew.

6. • Furculum - the fused
collarbones commonly
called the wishbone, suggest
that Archaeopteryx was
birdlike.

7. Characteristics of Birds
• The following characteristics distinguish birds from other
Vertebrates:
• Body covered with feathers.
• Bones are thin and hollow.
• A toothless, horny beak .
• Body temperatures is generated and regulated internally.
• The 4-chambered heart has a single right aortic arch.
• Amniote eggs are encased in hard, calcium-containing shells.
• Most species eggs are incubated in a nest.

8. • Soft, fluffy down feathers
cover body of nestling
birds and provide and
insulating undercoat for
adults.
• Contour feathers give
adult birds their
streamlined shaped and
provide coloration and
additional insulation.
• Flight feathers are
specialized contour
feathers on the wings and
tails.
Feathers

10. Beaks and Feet
• Hawks and eagles have
powerful beak and clawed
talons that help them
capture and then rip their
prey.
• Swifts have a tiny beaks
that opens wide like a
catcher’s mitt to share
insects in midair.

12. The feet of flightless birds, on the other hand are modified
for walking and running

14. Skeleton
• The sternum supports
the large breast muscles.
• The pygostyle, the
terminal vertebra of the
spine, support the tail
feathers, which also play
an important role.

15. Endothermy
• Generate and regulate body heat internally.
• Enables birds to inhabit both cold and hot climate.
• Body temperature ranges from 40- 46 degrees Celsius.
• To help conserve body heat, birds fluff out there feathers to
insulation.

17. • Food passes from the mouth
cavity straight to the
esophagus.
• Enlargement of the esophagus
called the crop stores and
moistens food.
• In the first chamber, the
proventriculus, gastric
fluids begin breaking down
the food.
• Then passes through the
gizzard, a muscular organ
that kneads and crushes the
food.
Digestive and Excretory system

19. Respiratory System

21. Circulatory System
4 chambered heart

22. Nervous System
• Birds have a large brains, relative to their size
• Cerebellum coordinates movement.
• Cerebrum controls complex behavior patterns
such as navigation, mating, and nest building.
• Have good color vision.
• Birds large eyes are located near the sides of its
head, giving a bird a wide field of vision.

23. 
Hearing important to nocturnal species that rely on sounds to
help them locate prey.

Birds lack internal ears-ear canal leads to a tympanic membrane,
called an eardrum.

Sense of smell is poorly developed except in ducks and flightless
birds.

Sense of taste helps birds avoid bitter-tasting or toxic foods.

24. Reproductive System

A female bird usually lays
eggs in the nest.

One or both parents will
incubate or warm the eggs
by sitting on them.

28. Order Anseriformes

Swans, geese, and ducks- waterfowl

Aquatic, webbed-feet for swimming

Feed on invertebrates, fish, grass...

Parental care is provided by female

29. Order Strigiformes

Owls

Sharp, curved beak, claws

Large, forward-facing eyes

Keen eyesight and hearing

30. Order Psittaciformes

Parrots, parakeets, macaws, cockatoos, & cockatiels

Live in tropics

Eat seeds and fruit

Vocal birds

32. Order Passeriformes

Over 5,900 species; wrens...

Feed on nectar, insects, seeds & fruits

Song-birds- males produce song

Syrinx- song is produced in this structure

33. Order Struthioniformes

Ostriches, rheas, emus, and cassowaries.

Ostriches cannot fly.

35. Order Galliformes

Turkeys, pheasants, chickens, grouse, and quails- fowl

Terrestrial birds- limited flying ability

Strong gizzard

Important part of human diet

37. Order Columbiformes

Pigeons & doves

Feed on fruits and grain

Crop secretes a nutritious milk-like fluid called crop milk