They ranged in height from . Their closest modern-day relatives are believed to be the seriemas. "Titanis walleri", one of the larger species, is known from Texas and Florida in North America. This makes the phorusrhacids the only known large South American predator to migrate north in the Great American Interchange that followed the formation of the Isthmus of Panama land bridge (the main pulse of the interchange began about 2.6 Ma ago; "Titanis" at 5 Ma was an early northward migrant).