challenge: What is a distinctive characteristic of non-fostercoopine paraceratheriids?
  
  A. A protruding nasal notch and large lower canine teeth
  B. A retracted nasal notch and enlarged upper and lower first incisors
  C. A long and flat skull with small premolars and molars
  D. A short and broad snout with large nasal bones
  Answer: 