| Named By: | Michael K. BrettinSurman in 1979 |
| Time Period: | Late Cretaceous, Maastrichtian |
| Location: | Argentina |
| Size: | Around 3 meters long |
| Diet: | Herbivore |
| Fossil(s): | Few individuals, but usually incomplete |
| Classification: | | Chordata | Reptilia | Dinosauria | Ornithischia | Ornithopoda | Iguanodontia | Hadrosauroidea | Hadrosauridae | Saurolophinae | |
| Also known as: | | Kritosaurus australis | |
Secernosaurus (meaning "severed lizard") is a genus of herbivorous dinosaur. Secernosaurus was a hadrosaur, a "duck-billed" dinosaur which lived during the Late Cretaceous. Its fossils have been found in Argentina. Its name comes from the fact that it lived in South America, which during the Mesozoic Era was part of the southern supercontinent of Gondwana. Most other hadrosaurs lived in the northern supercontinent of Laurasia, so it was separated from its relatives. It was believed to be the hadrosaur from Gondwana until the discovery of Willinakaqe salitralensis in 2011.
The type species is Secernosaurus koerneri, described in 1979. A species named in 1984, Kritosaurus australis, is thought to be synonymous.