Editing Pliocene (section)

==Oceans==
{{More citations needed|date=May 2021}}
Oceans continued to be relatively warm during the Pliocene, though they continued cooling. The [[Arctic sea ice ecology and history|Arctic ice cap formed]], drying the climate and increasing cool shallow currents in the North Atlantic. Deep cold currents flowed from the Antarctic.

The formation of the Isthmus of Panama about 3.5 million years ago<ref>{{Cite journal|last=Keigwin|first=Lloyd D.|date=1978-10-01|title=Pliocene closing of the Isthmus of Panama, based on biostratigraphic evidence from nearby Pacific Ocean and Caribbean Sea cores|url=https://pubs.geoscienceworld.org/gsa/geology/article-abstract/6/10/630/190760/Pliocene-closing-of-the-Isthmus-of-Panama-based-on|journal=Geology|language=en|volume=6|issue=10|pages=630–634|doi=10.1130/0091-7613(1978)6<630:PCOTIO>2.0.CO;2|bibcode=1978Geo.....6..630K|issn=0091-7613}}</ref> cut off the final remnant of what was once essentially a circum-equatorial current that had existed since the Cretaceous and the early [[Cenozoic]]. This may have contributed to further cooling of the oceans worldwide.

The Pliocene seas were alive with [[sirenia|sea cow]]s, [[Pinniped|seal]]s, [[sea lion]]s, [[Megalodon|shark]]s and [[Macroraptorial sperm whale|whales]].