Aciedactylus specializes in eating shellfish in the swampy estuaries and mangroves. Broad, splay-toed feet keep the dinosaur from sinking into the sodden mud and sand, but its most peculiar adaptation is the second pair of nostrils mounted atop its triangular nasal crests.
Aciedactylus’s primary nostrils can pinch shut when exhaling, forcing air into the resonating crests and small secondary nostrils to trumpet calls to one another. The main function of these secondary nostrils becomes clear during feeding. Scaling the primaries, Aciedactylus can breathe through the high-mounted secondary nostrils while most of its head is down in the shallow water or mud of the estuary, grubbing for shellfish.
Its teeth are short and thick for crushing mollusk and arthropod shells. The placid theropod instead defends itself with long bladelike claws on its fingers, flexing and brandishing them at potential threats to warn them away.