Fossils: A Fully Illustrated, Authoritative and Easy-to-Use GuideThis eBook is best viewed on a color device. |
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adapted ammonoids amphibia animals appeared areas armored arms beak became birds body bones bony brachial brachiopods branching Cambrian carnivores central changes closely common convex corals covered Cretaceous crinoids curved deposits developed Devonian Diameter dinosaurs early extinct eyes feet fins first fish fishes forms fossils geologic grooves growth lines head Height hinge important insects internal Jurassic known land largest late later leaves lines living Lower mammals marine Maximum length Mesozoic Middle million Mississippian North America numbers occur oldest Ordovician ornament outline oval pairs Paleozoic pedicle pelecypods Pennsylvanian PERIOD Permian places plants plates Pleistocene primitive prominent Recent replaced reptiles ribs rocks rounded scales seas sedimentary segments shaped shell short side Silurian similar simple slender smooth species spines straight strong strongly structure surface suture tail teeth Tertiary thick trees Triassic Upper usually valve vertebrates whorls wide widespread