ERA MILLION PERIOD YEARS SIGNIFICANTS EVENTS BEFORE PRESENT Cenozoic Quaternary Tertiary Mesozoic Cretaceous Jurassic ~~ I 0-1.6 1.6-66.4 66.4-144 144-208 208-245 I I First birds First dinosaurs and mammals First reptiles First insects Triassic ~~ ~~ Late Paleozoic Permian Carboniferous Devonian Earlv Paleozoic Silurian Ordovician Cambrian 286-360 360-408 I 505-570 First shellfish and corals Precambrian Time Proterozoic Era Archean Era Hadean Time 3.800-4.550 The Carboniferous perio is sometimes split into the Pennsylvanian Period (286-320 million years before present) and the Mississippian Period (320-360 million years before present). 33 7 338 A Dictionary o Environmental Economics, Science, and Policy f APPENDIX 6 (cont’d). Subdivisions of the Cenozoic Era PERIOD EPOCH THOUSAND YEARS BEFORE PRESENT SIGNIFICANTS EVENTS 1 Tertiarv Pleistocene 0-10 11-1,600 1,600-5,300 5,3 00-2 3,7 00 23.700-36,600 36.600-5 7.800 57,80046,400 First modern humans Olieocene Improved dating techniques and further study of stratigraphic sequences and fossils will require the adjustment of the periods and epochs given in Appendix 6. For further information, consult the University of California (Berkeley) Museum of Paleontology’s Web Geological Time Machine at http://www.ucmp.berkeley.edu/help/timeform.html. a review of the For concept of geologic time and how it is measured, see the USGS publication Geologic Time at http://pubs.USES.nov/pip/g;eotime/.
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