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Geol159 chap 9Triassic Park

Differentiated into a major dinosaur subgroup major

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Unformatted text preview: oss of postfrontal bone in skull Earliest Dinosaurs (Late Triassic, 225-230 Ma) (Late Eoraptor – not yet differentiated into a major dinosaur subgroup. major Herrerasaurus – theropod-like but only two sacral vertebrae. sacral Pisanosaurus – early ornithopod Later Triassic Dinosaurs Later (ca. 223 Ma) Saurischia – Coelophysis – ceratosaur theropod – Procompsognathus – allosauromorph theropod – Plateosaurus – prosauropod Ornithischia – Heterodontosaurus – early ornithischian with fang teeth fang Coelophysis Coelophysis Late Triassic Mass Extinction Late Two episodes: – Carnian/Norian boundary in Late Triassic Carnian/Norian – Norian/Jurassic boundary Norian/Jurassic Comet impact, not asteroid? – – – Shocked quartz fern spike Not yet found iridium layer Victims of the end-Triassic Extinction Extinction Phytosaurs Ornithosuchids Aetosaurs Rauisuchians Saltoposuchids Trilophosaurs, rhynchosaurs Tanystropheids Many therapsids Early Jurassic dinosaur radiation Early Footprints tell the pace of size increase – Two feet above the Triassic, ca. 20,000 years – Dinosaur footprints reach enormous sizes Crocodylomorphs chased off the dry land; Crocodylomorphs retreat into the swamps, rivers, lagooons retreat Mammals restricted to largely nocturnal Mammals habits habits...
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