Complex sentence: There are three genera of North American pocket gophers: "Cratogeomys", "Geomys", and "Thomomys", differentiated by the number of grooves on their anterior upper incisors.
Split into simpler sentences: There are three genera of North American pocket gophers, "Cratogeomys", "Geomys", and "Thomomys". They are differentiated by the number of grooves on the surfaces of the anterior aspects of their upper incisors.