How are chunks of time in the geologic timeline organized?

Which of these is a provisioning service people get from the ocean

What is the term for a water wave that is created by an underwater earthquake?

Fossils of ancestors of the modern horses show a small 4-toed almost dog-like browsing animal named eohippus over time the horses got larger lost toes and changed to a grazing diet what is the best explanation of why this change occurred