Throughout the Paleogene period, the sea level was still significantly higher than it is today. This led to the formation of wide and shallow seas over vast areas of continental plates. At the same time, the climate for most of the period was very warm. And, as always, the shallow and warm seas became one of the most diverse habitats on Earth.

Among the sea plants, there was a great variety of red algae, such as Pterigophycos, and green algae. In addition, in the shallows, angiosperms from the land grew - sea grasses, such as Halochloris and Cymodoceites. Their variety only increased throughout the period.

Ancient coral reefs were forming. The various invertebrates living at the bottom of the seas, as well as in the water column, were little different from the modern ones. Throughout the period, almost all groups of modern bony fish were formed, further increasing the similarity of the Paleogene sea world with the modern one. Sharks and rays continued their development, fully rec...