Post #1925878

@jamesmarshall @leaverou Birds are tetrachromatic because their ancestors were larger carnivorous dinosaurs, they didn't lose their colour receptors because they were generally diurnal creatures. Mammals are mostly bichromatic (aside from a few exceptions like apes) because our ancestors were small burrowing creatures that couldn't go out during the day with all the big bird ancestors, so they only came out at night, as such our ancestors lost a large chunk of their unused colour vision.