In the seas were an unprecedented diversity of marine reptiles - the dolphin-like ichthyosaurs, the lizard-like pachypleurosaurs and thalattosaurs, the long-necked seal-like nothosaurs, walrus-like placodonts, the turtle-like henodonts, and the long-necked Pistosaurs. Most of these animals were seriously diminished by the end-Carnian extinction event (possibly caused by an extraterrestrial impact - a comet or asteroid). New forms of animal life evolved to take their place, or suddenly came into dominance after millions of years of obscurity.