The seriemas are the sole extant members of the small and ancient family Cariamidae. Once believed to be related to cranes, they have been placed by one recent study near the falcons and parrots. There are two species; the Red-legged Seriema, found from eastern Brazil to central Argentina, and the Black-legged Seriema, found in northwest Argentina and Paraguay.

The seriemas are thought to be the closest living relatives of a group of gigantic (up to 3 m tall) carnivorous "terror birds", the phorusrhacids, which are known from fossils from South and North America.

Ecologically they are the South American counterpart of the Secretary Bird. They feed on insects, snakes, lizards, frogs, young birds, and rodents, with small amounts of plant food. When seriemas catch small reptiles, they beat the prey on the ground or throw it at a hard surface to break resistance and also the bones. If the prey is too large to swallow whole, it will be ripped into smaller pieces with a sickle claw reminiscent of those in deinonychosaurs like Velociraptor, by holding the prey in the beak and tearing it apart with the claw.