Image:Geologic time and mass extinctions.png

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Geologic_time_and_mass_extinctions.png‎ (4KB, MIME type: image/png)

1 The Quaternary period
2 Margin of error for dates
3 Summary
4 Licensing

[edit] The Quaternary period

I checked several reputable online resources before creating this image. The Illinois State Geological Survey glossary entry for the Cenozoic era cautions "Some authors do not include the Quaternary, considering it a separate era." The Geology department at Eastern Illinois University defines the Quaternary as the "Period of geologic time from about 2 million years ago until the present," while the United States Geological Survey website says it covers the last 1.6 million years.

If the Quaternary period was shown at the same scale as the other periods it wouldn't be visible on this chart (less than 1 pixel high), so I placed it on a color gradient.

[edit] Margin of error for dates

The table below shows the discrepancies for the dates of the five major mass extinctions from a small selection of sources. To avoid making the image too clutered, I included just two date ranges for the mass extinctions whose dates vary most widely between the different sources.

The five major Mass Extinctions					Source
(millions of years ago)					Source
65	200	251	360	444	Wikipedia's Extinction event article (May 18, 2006)
65	210	245	370	440	The Sixth Extinction -- American Institute of Biological Sciences
65	208	245	360	438	College of Natural Sciences, University of Hawaii
67	205	251	370	440	A Brief History of the Universe -- University of California at Riverside
65	205	245	367	438	Scientific American special issue:"Life in the Universe" (1994)

The author of the Sixth Mass Extinction article, paleontologist Dr. Niles Eldredge, is Curator-in-Chief of the permanent "Hall of Biodiversity" exhibition at the American Museum of Natural History. The ActionBioscience.org website belongs to the American Institute of Biological Sciences.

[edit] Summary

Description	Geologic time and mass extinction events.
Source	self-made
Date	2006-05-17
Author	Kerry Watson -- Bookish
Permission	GFDL (self made)
Other versions	None

[edit] Licensing

I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
Subject to disclaimers.

File history

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(del) (cur) 04:50, 19 May 2006 . . Bookish (Talk | contribs) . . 288×481 (3,384 bytes) (Reverted to earlier revision)
(del) (rev) 04:49, 19 May 2006 . . Bookish (Talk | contribs) . . 288×481 (3,324 bytes) (Reverted to earlier revision)
(del) (rev) 19:42, 18 May 2006 . . Bookish (Talk | contribs) . . 288×481 (3,384 bytes)
(del) (rev) 15:41, 18 May 2006 . . Bookish (Talk | contribs) . . 288×481 (3,384 bytes)
(del) (rev) 12:17, 17 May 2006 . . Bookish (Talk | contribs) . . 288×481 (3,324 bytes) ( == Summary == {{Information| |Description = Geologic time and mass extinction events. |Source = self-made |Date = 2006-05-17 |Author = Kerry Watson -- Bookish |Permission = GFDL (self made) |other_versions = None}} == Licensing == {)