Tetrastylus

Tetrastylus is an extinct genus of dinomyid rodent that lived in South America during the Neogene and Quaternary periods.^[1]

Tetrastylus Temporal range: Miocene–Pleistocene PreꞒ Ꞓ O S D C P T J K Pg N
Skull of Tetrastylus intermedius, taken 2022
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Family:	Dinomyidae
Genus:	†Tetrastylus Ameghino, 1886
Species
Tetrastylus angustidens Rusconi, 1934 Tetrastylus araucanus Ameghino, 1904 Tetrastylus atrophiatus Rovereto, 1914 Tetrastylus intermedius Rovereto, 1914 Tetrastylus laevigatus Ameghino, 1886 Tetrastylus montanus Ameghino, 1891

Distribution

Tetrastylus is known from Argentina,^[2] Uruguay,^[3] Brazil, and Venezuela.^[1]

Palaeobiology

Analysis of the occipitocervical morphology of Tetrastylus intermedius specimens from northwestern Argentina suggests that this species was a terrestrial animal, but it still retained some holdover traits related to arborealism from its evolutionary past, such as larger paracondyles relative to the modern pacarana and a size-proportionate head.^[2]