Reptiles

1. Reptiles Science, Peterson

2. Reptiles • Reptiles are ectotherms with thick, dry, waterproof skin covered with scales. • Reptiles breathe with lungs which uses diffusion to move oxygen into the blood stream. • Most reptiles have three chambered heart. • This has a partial wall in the ventricle. • Crocodilians have four chambered heart.

3. Reptiles • Reptiles use internal fertilization and lay eggs with a shell. • Amniotic egg provides everything the embryo needs.

4. Reptiles • Reptiles are a very diverse group and live on every continent except Antarctica. They are divided into three groups: • Lizards and snakes have jaws that can unhinge.

5. Reptiles • Turtles have a two-part shell made of bone-like plates.

6. Reptiles • Crocodilians are lizard-like with large, deep scales on their backs. • Crocodiles have narrow head with triangular snout. • Alligators have wide head with rounded snout. • Crocs are among a small group of reptiles who care for their young.

7. Reptiles • Reptiles are important for pest control. • Reptiles first appear in the fossil record about 345 million years ago. Dinosaurs are descendants of early reptiles.

8. Reptiles

9. Reptiles • The basic timeline is a 4.6 billion year old Earth, with (very approximately): • 4 billion years of simple cells (prokaryotes), • 3 billion years of photosynthesis, • 2 billion years of complex cells (eukaryotes), • 1 billion years of multicellular life, • 600 million years of simple animals, • 570 million years of arthropods (ancestors of insects, arachnids and crustaceans) • 550 million years of complex animals • 500 million years of fish and proto-amphibians, • 475 million years of land plants, • 400 million years of insects and seeds, • 360 million years of amphibians, • 300 million years of reptiles, • 200 million years of mammals, • 150 million years of birds, • 130 million years of flowers, • 65 million years since the non-avian dinosaursdied out and • 200,000 years since humans started looking like they do today.

10. December