Phytosaurs are a group of semi-aquatic, crocodilian-like reptiles from the Triassic period. What primarily differentiates them from crocodilians is the position of their nostrils. Crocodilian have their nostrils positioned at the top of the snout, whereas phytosaurs have theirs near the top of the head. All of the phytosaurs died out before the Jurassic period.