C. Primates originated in North America and were unable to migrate to Africa until after 50 million years ago. D. suitable ecological niches in Africa were totally occupied by insectivores and rodents. E. the lemurs that lived in Madagascar between 80 and 50 million years ago were unable to cross the straits between Madagascar and Africa. B. monkeys have fewer genes than chimpanzees. C. chimpanzees have a longer fossil record.
E. monkeys have more canines and toes.
B. are valid only if they were originally suggested by Linnaeus in 1758. C. must change whenever more genetic information becomes available. D. always end in -idae. E. always end in -us. B. robust mandibles with reduced canines, large molar chewing surfaces, and thick dental enamel.