 In particular, the Cretaceous–Paleogene extinction event wiped out the pterosaurs, plesiosaurs, ornithischians, and sauropods, alongside many species of theropods, crocodyliforms, and squamates (e.g., mosasaurs).Modern non-avian reptiles inhabit all the continents except Antarctica, although some birds are found on the periphery of Antarctica.Several living subgroups are recognized