How does your "core sample" picture of the earth's layers differ from the actual layers of the earth. i actually need help its due tmrw and i cant think of anything to write. please help me​

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