What do the similarities in limb structures of mammals reptiles and birds tell us about them

Which of the following is a period in the paleozoic era? devonian cambrian permian all of the above

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

Who discovered tuberculosis bacteria?