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Terrestrial Vertebrates
Section 32.2
Early Reptiles
Important adaptations to terrestrial life that amphibians do not have:
1. Water tight skin
2. Water tight eggs
Dinosaurs
Beginning 235 million years ago Pangaea broke up and provided many
different habitats for dino evolution Reasons for dino success:
1. Leg structure – position directly under the body
2. Drought resistance
3. Extinction of other competing animals
Dino debate
Ectotherms – ‘cold-blooded’; body temp changes with surroundings need less food; modern fish, amphibians, reptiles
Endotherms – ‘warm-blooded’; body temp remains the same need more food; modern birds & mammals
Debate about dinos – which one? Reason(s) for dino extinction?
Climate became cooler Asteroid hit earth and caused loss of plant life Success of other species Some combination…
Evolution of Birds
Archaeopteryx – oldest bird fossil; basically a dinosaur with feathers
Key feature of birds – feathers Today there are more bird species than any
other terrestrial vertebrate They live in a wide variety of habitats and are
adapted to many different lifestyles
Modern Reptiles
Only 4 remaining orders of reptiles:
1. Turtles
2. Snakes & lizards
3. Tuatara
4. Crocodilians – crocodiles and alligators
Along came mammals
Appeared about 220 million years ago Key features: fur and mammary glands Three groups of modern mammals:1. Monotremes – egg laying mammals; spiny
anteater and duck-bill platypus2. Marsupials – pouched mammals;
kangaroo, koalas, wombats, possum3. Placental mammals – young develop
attached to the placenta within mother