Vertebrates

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Birds - reptilian anatomy modified for Flight

Derived Characters of Birds:

Many characters of birds are adaptations that facilitate flight

The major adaptation is wings with keratin feathers

Other adaptations include lack of a urinary bladder, females with only one ovary, small gonads, and loss of teeth.

Slide 39

Form fits function: the avian wing and feather

(a) Wing

(b) Bone structure

(c) Feather structure

Finger 1

Finger 2

Finger 3

Palm

Hook

Vane

Barbule

Barb

Shaft

Wrist

Forearm

Shaft

Slide 40

Flight enhances hunting and scavenging, escape from terrestrial predators, and migration.

Flight requires a great expenditure of energy, acute vision, and fine muscle control.

Birds probably descended from small theropods, a group of carnivorous dinosaurs. By 150 million years ago, feathered theropods had evolved into birds.

Archaeopteryx remains the oldest bird known.

Slide 41

Archaeopteryx, the earliest known bird

Airfoil wing

with contour

feathers

Toothed beak

Wing claw

Long tail with

many vertebrae

Slide 42

Diversity among living birds

(a) Emu - flightless

(b) Mallards - web feet

(c) Laysan albatrosses

(d) Barn swallows

Slide 43

Derived Characters of Mammals

Mammals, class Mammalia, are represented by more than 5,300 species.

Mammals have

Mammary glands, which produce milk

Hair

A larger brain than other vertebrates of equivalent size

Differentiated teeth.

Slide 44

evolution of the mammalian ear bones

(b) In mammals, the articular and quadrate bones are incorporated into the middle ear.

(a) In Biarmosuchus, an early synapsid, the articular and

quadrate bones formed the jaw joint.

Middle ear

Temporal

fenestra

Jaw joint

Eardrum

Present-day reptile

Present-day mammal

Malleus (articular)

Incus (quadrate)

Sound

Stapes

Inner ear

Eardrum

Middle ear

Sound

Inner ear

Stapes

Key

Quadrate

Articular

Squamosal

Dentary

Slide 45

By the early Cretaceous, the three living lineages of mammals emerged: monotremes, marsupials, and eutherians.