Dyrosaurus is a genus of extinct crocodylomorph that lived from the upper Cretaceous to the Eocene period, surviving the K-Pg extinction event. Dyrosaurus are linked to pholidosaurids as a clade and are defined as slender-snouted, fish-eating specialists adapted to near-shore marine habitats.
The Dyrosauridae are a group of mostly marine, long jawed, crocodile-like quadrupeds up to 6 metres (20 ft) long. Based on bone tissue evidence, it has been hypothesized that they were slow-growing near-shore marine animals with interlocking closed jaws, able to swim as well as walk on land. External nostrils at the posterior end of its snout and an internal naris in its pterygoid indicated a habit of hunting while swimming with the top of the head above the water, enabling it to breathe while stalking prey.