Named By: Francisco P. Moreno - 1889.
Classification: Chordata, Aves, Cariamae, Phorusrhacidae, Mesembriornithinae.
Species: M. incertus, M. milneedwardsi.
Size: Up to 1.5 meters tall.
Known locations: Argentina.
Time period: Tortonian of the Miocene through to the Gelasian of the Pleistocene.
Fossil representation: Enough fossils to identify one species, but the bones are fragmentary.
was a middle of the range 'terror bird’ with regards to its size,
but it was one of the last known to have lived. In overall build
Mesembriornis was similar to other medium sized
phorusrhacids such as
and may have also filled the same ecological niche as its
Mesembriornis is usually depicted as a fast running predator, and while it could have used its beak to attack and kill prey it has also been theorised that it may have used its long legs to kick prey as well as possibly other members of the same genus in interspecific combat as well as to defend its kills from other predators.