Closure of the Isthmus of Panama about 3 million years ago (Ma) was accompanied by dramatic changes in Earth's climate and biosphere. The Greenland ice sheet grew to continental extent and the great cycles of ice ages commenced dominating climate variability henceforth. Disruption of water mass exchange between the Atlantic and the Pacific Oceans led to different evolution of marine species on either side of the land bridge, while land‐based organisms including mammals and other animals took the advantage to colonize an entire subcontinent. A 2‐day workshop at the University of Kiel (Germany) summarized our current knowledge of this time period and identified areas for new research.