Answer:
The Eocene Period is experiencing net gain in energy while Cryogenian Period is experiencing a net loss in energy.
Step-by-step explanation:
In Eocene Period, the population of mammals such as horses , whales and bats etc were high due to the presence of high amount of food and good atmospheric condition such as high temperature while the population of animals were low in Cryogenian Period due to the presence of very low temperature which experiencing loss of energy. Most of area of the earth consist of icy desert.