Macroeuphractus is a genus of extinct armadillos from the Late Miocene to Late Pliocene of South America. The genus is noted for its large size, with Macroeuphractus outesi being the largest non-pampathere or glyptodont armadillo discovered, as well as its specializations for carnivory, unique among all xenarthrans.[1]
There are three currently recognised species of Macroeuphractus: M. outesi, M. retusus and M. moreni. The former, the type species, is known from one specimen from the Late Pliocene of Buenos Aires, Argentina. This specimen is composed of a fairly well preserved skull as well as numerous post-cranial elements. It represented a considerably large species at around 100 kilograms (220 lb), although it is possible that it was actually closer to 30 kilograms (66 lb), at a little over 1 meter (3 ft 3 in) in length it would still be a decently sized predator.[2][3][4]
Macroeuphractus is traditionally grouped with euphractines; it was named after its similarity with Euphractus itself. The most recent phylogenetic examinations confirm its status as at least a sister group to euphractines, along with Paleuphractus, Doellotatus and Proeuphractus.[6]
Macroeuphractus is one of the few known xenarthrans to have specialised extensively for a carnivorous lifestyle. Modern euphractine armadillos (such as the modern six-banded armadillo) are fairly dedicated omnivores, but Macroeuphractus shows several features that indicate hypercarnivory:
These features are unusual among xenarthrans but are more in line with predatory mammal groups.[7][8]
Like most armadillos, Macroeuphractus was fossorial, and it probably could dig out small and medium-sized mammals such as caviomorph rodents, small notoungulates and argyrolagoidean paucituberculates. Species like Macroeuphractus outesi were fairly large and presumably had an apex predator status in their faunal communities.