Ypresian Stage

What happened during this time?

Geophysical

• The Ypresian had the highest mean annual temperatures of the entire Cenozoic Era

  • Dramatic warming event probably due to the release of methane that had been trapped in sediments on the ocean floor

  • Temperatures about 30° C

  • Relatively low temperature gradients from pole to pole

  • High precipitation in a world that was essentially ice-free

• Land connections existed between Antarctica and Australia, between North America and Europe through Greenland, and probably between North America and Asia through the Bering Strait

  • It was an important time of plate boundary rearrangement: spreading centers and transform faults changed

  • Significant effects on oceanic and atmospheric circulation and temperature

Biological

Azolla Event: 50-49 Ma

• • Extensive mats of the water fern, Azolla, grew on top of the Arctic Ocean

  • Anoxic saltwater was over-topped by freshwater zone from heavy inflow from rivers  

  • These floating plants absorbed mass quantities of carbon dioxide, and when they died sank into the anoxic zone of the ocean, preventing decomposition

  • Cores from the sediments under the Arctic ocean, show Azolla fossils that are meters thick

  • The sequestration of large amounts of carbon dioxide caused CO2 levels to drop world wide

  • This creates a cooling effect that progressed for 50 million years until the Pleistocene glaciations

• The oldest known nightshade (Solanaceae) is found from around 52 million years ago (Penn State 2016)

• Earliest evidence of an orchid found as a pollinia attached to a gnat trapped in amber

• Polar-region fossils include warm-weather species of plants, alligators, turtles, and flying lemurs

• Artiodactyls became smaller (dwarfism) around 55-53 Ma due to global warming

• Titanomyrma, a giant ant species, the size of a hummingbird, found in Wyoming (Archibald et al. 2001)