The final phase of the
Angiosperm Terrestrial Revolution occurred during the EECO. The supergreenhouse climate of the EECO fostered extensive floral diversification and increased habitat complexity in North American terrestrial biomes. The Okanagan Highlands in British Columbia and Washington became a biodiversity hotspot from which newly evolved lineages of temperate-adapted plants radiated from following the end of the EECO. The climate was warm enough to allow palms and
palm beetles to inhabit upland regions of British Columbia and Washington. Ellesmere Island became inhabited by basal
primatomorphs, while Canada's Western Arctic was home to crocodyliforms. Crocodyliform diversity in North America was very high. The leadup to the EECO was marked by an increase in mammal diversity in Wyoming's
Bighorn Basin. Across North America, the EECO's warmth and humidity promoted increased floral diversity and habitat complexity, which in turn increased mammalian diversity. The end of the EECO caused a drop in mammalian diversity known as the Bridgerian Crash. Northern Yakutia was covered in mangroves.
Mongolia witnessed a humidification event that transformed it from a shrubland into a forest and significantly reducing local wildfire incidence. In
South America, the EECO coincided with the
Itaboraian South American Land Mammal Age.
Cingulates diversified over the course of the EECO. In
Africa, the end of the EECO brought about a
hyaenodont turnover, with subfamilial richness among hyaenodonts increasing. The northern margins of the
Australo-Antarctic Gulf, then located at 60-65 °S, were covered in wet-tropical lowland vegetation.
Nypa pollen is recorded in southeastern Australian sediments.
Apectodinium became abundant in the seas, and is often used as a biostratigraphic marker of the EECO. The central Tethys in what is now northeastern Italy was a hotspot of coral diversity, with its mesophotic deltaic environment acting as a refugium. At Shatsky Rise, the planktonic
foraminifera Morozovella and
Chiloguembelina declined in abundance.
Acarinina became the dominant planktonic foraminifer in this locality.
Morozovella underwent a switch from dextral to sinistral coiling across the EECO. The
euryhaline dinoflagellate Homotryblium became superabundant at the site of Waipara in
New Zealand during the early and middle EECO, reflecting the occurrence of significant stratification of surficial waters as well as increased salinity. The productivity of calcareous nannoplankton increased. In the equatorial Atlantic and Pacific,
Toweius declined in two phases during the peak of the EECO as
Discoaster achieved peak abundance, with
Campylosphaera,
Umbilicosphaera, and
Calcidiscus also thriving. The conclusion of the EECO in these regions was marked by their declines and the expansion of
Reticulofenestra. == Geologic effects ==