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9 Cards in this Set
- Front
- Back
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Anapsid
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No holes in the skull. Ex: Turtles, amphibians, and fish.
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Synapsid
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Only the lower opening. Ex: Mammals and their relatives.
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Diapsids
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Two holes. Ex: Most reptiles, dinosaurs, pterosaurs, and birds.
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What evolved at the end of the Triassic
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First frogs, salamanders, turtles, lizards, snakes, crocodiles, mammals and dinosaurs. The Triassic is known as the "Dawn of the Dinosaurs" also the "Dawn of Modern Ecosystems"
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Dicynodonts
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First mammal like reptile.
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Archosauria
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Ruling Reptiles. Archosaurs divided into two groups: Crurotarsi and Ornithodira. Crurotarsi followed the line towards crocodiles. Ornithodira followed the line towards pterosaurs, dinosaurs and birds.
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Dinosaur Origins
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Dinosaurs diverged from their Archosaur ancestors about 230 million years ago during the Middle to Late Triassic period.
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Ischigualasto Formation
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Richest deposit dating from this time at the beginning of the Late Triassic Period is at the Ischigualasto Formation of Argentina. Gray colored rocks deposited in a humid environment have theropods like Eoraptor and Herrerasaurus. The most primitive ornithischian found in the formation, Pisanosaurus, is also found in the formation.
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Characteristics of the first dinosaurs
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Upright posture, open hip socket, opposable thumb for grasping, and a functionally three-fingered hand.
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