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. 2012 Sep;5(5):595–607. doi: 10.1242/dmm.009613

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© 2012. Published by The Company of Biologists Ltd

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Share Alike License (http://creativecommons.org/licenses/by-nc-sa/3.0), which permits unrestricted non-commercial use, distribution and reproduction in any medium provided that the original work is properly cited and all further distributions of the work or adaptation are subject to the same Creative Commons License terms.

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Fig. 2. — Isotopic trends over the last 5 million years. Oxygen-18 (¹⁸O) isotope levels are directly equivalent to average global temperature. As the world became steadily cooler, shorter-term climate stochasticity also increased substantially, indicating less stable ecological conditions. Based on published data (Lisiecki and Raymo, 2005). BP, before present.