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Warm Up 6/13/07. What is the major source of free oxygen in the atmosphere? a. water c. molten rock b. silicate minerals d. green plants The first truly large organisms on Earth were ____. a. cephalopods c. dinosaurs b. lobe-finned fish d. trilobites
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Warm Up 6/13/07 • What is the major source of free oxygen in the atmosphere? a. water c. molten rock b. silicate minerals d. green plants • The first truly large organisms on Earth were ____. a. cephalopods c. dinosaurs b. lobe-finned fish d. trilobites • During the Pennsylvanian period, large tropical swamps extended across North America, eventually forming ____. a. tropical rain forests c. inland seas b. vast coal deposits d. mountain ranges Answers: 1. d 2. a 3. b
Mesozoic Era:Age of Reptiles Chapter 13, Section 3
Mesozoic History • The Mesozoic era spanned about 183 million years, and it is divided into three periods: the Triassic, Jurassic, and Cretaceous • The Mesozoic era began with much of the world’s land above sea level (very few marine fossils are found in North America from the Triassic Period) • In the Cretaceous, shallow seas invaded much of western North America creating great swamps (leaving large coal deposits) • A major event of the Mesozoic era was the breakup of Pangaea • This process lasted for 200 million years, forming the Atlantic Ocean • It also caused the North American plate to override the Pacific plate, causing massive deformation, forming the Sierra Nevada and Rocky Mountains
Mesozoic Life • When the Mesozoic began, its life forms were the survivors of the great Paleozoic extinction • On land, conditions favored life that could adapt to drier climates • Gymnosperm – seed-bearing plant that bears its seeds on the surface of cones • Unlike the first plants to invade land, gymnosperms were not restricted to living near the water’s edge, and they could take advantage of nutrients and space available in drier areas • The gymnosperms quickly became the dominant plants of the Mesozoic • Gymnosperm trees included the cycads, the conifers, and the ginkgoes • Among the animals, reptiles readily adapted to the drier Mesozoic environment, being the first true land animals • Reptiles have shell-covered eggs that can be laid on land
Reptiles Dominate • With the perfection of the shelled egg, reptiles quickly became the dominant land animals • They continued this dominance for 160 million years • Dinosaur – land-dwelling reptile of the Mesozoic era • The reptiles made an amazing adaptation, one previously made by insects, they began to fly (the pterosaurs) • Another group of reptiles led to the more successful flyers—the birds • Some reptiles also returned to the sea, but retained their reptile teeth and breathed with their lungs • At the end of the Mesozoic, many reptile groups became extinct • Only a few types of reptiles survived to recent times (the turtles, snakes, crocodiles, and lizards) • Most scientists believe that the extinction of the large reptiles was caused by a large meteorite that collided with Earth
Assignment • Read Chapter 13, Section 3 (pg. 377-381) • Do Section 13.3 Assessment #1-5 (pg. 381)