Acid-fast staining is of medical diagnostic interest, especially as organisms that can cause tuberculosis and leprosy are included in a particular genus that is acid-fast. what is this genus of bacteria?

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