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The Mesozoic Era. When Dinosaurs Ruled the Earth. The Mesozoic Era. Began approximately 245 million years ago after a major mass extinction. Is subdivided into 3 periods: Triassic Jurassic Cretaceous Ends about 66 million years ago with a major mass extinction.
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The Mesozoic Era When Dinosaurs Ruled the Earth
The Mesozoic Era • Began approximately 245 million years ago after a major mass extinction. • Is subdivided into 3 periods: • Triassic • Jurassic • Cretaceous • Ends about 66 million years ago with a major mass extinction
The Triassic Period245 - 206 million years ago • Immediately after the Permian Mass Extinction • Lots of new area is open for animals to live • Three general types of animals: • holdovers from before the extinction • new groups that lasted only a short time • new groups that lasted a long time
Triassic Plant Life • Mosses • Scale Trees (like palm trees) • Ginkos
Two Groups of Dinosaurs • Ornithischian • Hips were similar to modern bird hips • Carnivorous short-necked • Herbivorous, long-necked • Saurischian • Hips were similar to reptile hips • Herbivorous with grinding-teeth • Herbivorous without grinding-teeth
Earliest Dinosaurs(Triassic) Pisanosaurus Length:3 feet Height:1 foot Weight:15 pounds Eoraptor: Length:3 feetHeight:1 feetWeight:20 pounds Lesothsaurus: Length:3 feet Height:1 foot Weight:15 pounds
The Jurassic Period206 - 144 Million Years Ago • Giant plant-eating dinosaurs • Vicious carnivore dinosaurs • Oceans full of fish, squid, sharks, etc. • Ichthyosaurs and Plesiosaurs • Pterosaurs • Birds
Jurassic Plant Eating Dinosaurs • Many different forms • Many had ‘armor’ to protect themselves • Triceratops • Ankylosaurus • Many very large (larger than a Rhino/Hippo) • Some were extremely large (as long as a city block): Diplodocus Triceratops
Ankyloasaurus Diplodocus
Jurassic Carnivorous Dinosaurs • Many different forms • Some were very large: • Tyrannosaurus Rex • Allasaurus • Some were smaller: • Raptors, and many more • All had sharp teeth, claws, and speed
Jurassic Marine Dinosaurs • Most with similar shapes as dolphins or sharks • Ate fish and other marine animals • Some were VERY large • All could swim VERY fast Ichthyosaurus
Jurassic Pterosaurs • Pterodactyls and Pterosaurs • Most had trouble walking • Were very good flyers • Had hollow bones • Small (~ 1 foot) and very large (~ 16 feet)
Jurassic Birds(?) - Archaeopteryx • Not a Pterosaur • Jaws and bone structure like dinosaurs • Bones are hollow, like birds • Feathers • Was this an evolutionary link between dinosaurs and birds?
The Cretaceous Period144 - 66 million years ago • The last period when Dinosaurs lived • Ends with a mass extinction around 66 million years ago • First flowering plants!
Cretaceous Plants • First plants with flowers • Their appearance was very rapid • They appeared at the same time as the number of insects increased… • Could insects have helped the flowering plants evolve?
The Cretaceous Mass Extinction • Approximately 60% of all species went extinct. • Affected many land animals/plants • Affected fewer marine animals
What organisms went extinct? • All dinosaurs • All pterosaurs • All ichthyosaurs • Many terrestrial plants • Many marine animals
What organisms survived? • MAMMALS (!) • Birds • Many plants (ferns were the most successful plant for a while) • Trees with flowers • Small lizards/crocodiles/alligators/turtles • Fish, squids, sharks, etc.
What caused the extinction? • Meteorite impact theory • 66 million years ago, a ~10 km wide meteorite struck the Earth near what is now Mexico.