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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- Fall '10
- Triassic, Late Triassic
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