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Section 1 Origin & Evolution of Birds

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1 Section 1 Origin & Evolution of Birds
Chapter 42 Birds Section 1 Origin & Evolution of Birds

2 Characteristics Feathers- composed of keratin, essential for flight, insulate body Wings- modified forelimbs, covered by feathers Lightweight, rigid skeleton- bones are thin & hollow Endothermic metabolism- high body temperature

3 Characteristics Unique respiratory system- rapid metabolism, lungs connected to air sacs, oxygen-rich Beak- no teeth, horny sheath made of keratin Oviparity- lay amniotic eggs- eggs are incubated by both parents

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7 Evolution Similarities between birds & dinosaurs
S-shaped neck, unique ankle joint, & hollow bones Thought to have evolved from small, fast running dinosaurs Archaeopteryx

8 Archaeopteryx

9 Archaeopteryx Shapes of feathers are visible
Feathers cover wings, forelimbs, & its body and tail Hollow bones & furcula- wishbone Teeth, claws on forelimbs, long tail

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11 Origin of Flight Hypothesis 1: ancestors of birds were tree-dwellers that lived in trees- glided and wings evolved Hypothesis 2: ancestors of birds were land-dwellers- wings evolved to stabilize and protect against predators

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13 Evolution after Archaeopteryx
Only two of the modern orders of birds appeared after the mass extinction. 40 million years ago, most modern orders of birds originated

14 REVIEW!!! List two unique features of a bird’s skeleton.
What are two functions of feathers? Identify the characteristics that birds have in common with dinosaurs.


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