Editing Geologic temperature record (section)

=== Cretaceous thermal optimum ===
{{main|Cretaceous Thermal Maximum}}

During the later portion of the [[Cretaceous]], from {{Ma|100|66}}, average global temperatures reached their highest level during the last ~200 million years.<ref name="Renne2013">{{cite journal |last1=Renne |first1=Paul R. |last2=Deino |first2=Alan L. |last3=Hilgen |first3=Frederik J. |last4=Kuiper |first4=Klaudia F. |last5=Mark |first5=Darren F. |last6=Mitchell |first6=William S. |last7=Morgan |first7=Leah E. |last8=Mundil |first8=Roland |last9=Smit |first9=Jan |title=Time Scales of Critical Events Around the Cretaceous-Paleogene Boundary |journal=Science |date=7 February 2013 |volume=339 |issue=6120 |pages=684–687 |doi=10.1126/science.1230492 |pmid=23393261 |bibcode=2013Sci...339..684R|s2cid=6112274 }}</ref> This is likely to be the result of a favorable configuration of the continents during this period that allowed for improved circulation in the oceans and discouraged the formation of large scale ice sheet.{{Citation needed|date=April 2008}}