Paleocene

The Paleocene ( ), or Palaeocene, is a geological epoch that lasted from about 66 to 56 Ma (million years ago). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name comes from Ancient Greek παλαιός (palaiós), meaning "old", and καινός (kainós), meaning "new", translating to "the old part of the Eocene".

rapid (in geological terms) global warming, profound changes in ecosystems, and major perturbations in the carbon cycle which started about 55.0 million years ago