Why did small predatory dinosaurs die out?
Groups which became totally extinct include: • Non-avian dinosaurs. Note: most paleontologists regard birds as the surviving dinosaurs. • Pterosaurs Groups which suffered heavy losses include: • Birds. Some groups became extinct, including Enantiornithes and Hesperornithiformes. • Marsupials. The Northern hemisphere family of marsupials became extinct, but those in Australia and South America survived. • Freshwater mussels and snails also suffered heavy losses in North America. But some other groups were relatively unaffected: • Insects. These show no sign of reduced diversity, unlike at the Permo-Triassic extinction. • Amphibians • Turtles • Lepidosaurs. These include tuataras, lizards, snakes and amphisbaenians. • Champsosaurs (semi-aquatic archosauromorphs) – they later died out in the early Oligocene. • Crocodilians • Modern birds (Aves), which are not closely related to the bird groups which became extinct • Monotremes, egg-laying mammals. • Multituberculates, although they later
