[4] The big lutrine opossum is distributed in Brazil, Argentina, Bolivia, Uruguay, Paraguay, Colombia and Guyana.

[5] The big lutrine opossum builds tight nests made of grass and reeds or utilize abandoned armadillo or viscacha burrows.

[4] Captive individuals have been observed eating butterfish mixed with meat, frogs, earthworms, shrimp and mice.

[3] Its long body, proportionally short limbs, and no undulation of the vertebral column disqualifies it from being categorized as a specialized semi-aquatic mammal.

[5] By employing a variety of gaits its locomotion abilities allows it to run, walk, climb, swim through all the different kinds of obstacles found in the grassy-woodland and marshy areas in which it lives.

[3] Fossils found in Minas Gerais, Brazil indicate that the big lutrine opossum emerged in the late Pleistocene epoch.

Lutreolina fossils found in Tarija, Bolivia as well as samples uncovered across Argentina also indicate appearance of lutrine opossum ancestors during the late Pleistocene.