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Explore the Mesozoic Era, from Triassic to Cretaceous periods when dinosaurs roamed the Earth, their evolution, plant life, and the catastrophic mass extinctions. Learn about fascinating creatures like Pisanosaurus, Eoraptor, and iconic species like Triceratops and Tyrannosaurus Rex.
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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.