The mix-up between to genera Marmosa and Marmosops was common due to the similar appearances including size and other external features.

[1] The dentition is similar in morphology between the two groups, with the exception of the deciduous lower third premolar varying from one genus to the next.

The similarity between the two continues to cause the genus Marmosops to be frequently misidentified due to the lack of knowledge regarding the species along with the overlooked traits that help separate them from other opossums.

[1] The Marmosops are also commonly confused with the genus Gracilinanus, but this is quickly ruled out by a large number of differing characteristics.

Many females of the M. paulensis species are known to be extremely territorial with a strong defense of their food, especially while in the presence of their young.

[14] The main habitat for the Marmosops is found between the Neotropical humid forests ranging from Panama to the South of Brazil and sometimes in Bolivia as well.

[15] The genus is never found to live up in a canopy (biology) or in the trees, but instead typically prefer more accessible habitats where it is easier to hide.

[14] There is a high reproduction rate in the months of September through March for M. paulensis, with more mating occurring when there is a larger food supply.

[18] Successful breeding depends on the presence of females, and many may have multiple mating partners in order to produce more offspring if they do not die after one event.

[12] The M. paulensis species have higher breeding rates when the length of day is longer and there is more fruit available to eat.

[18] The M. incanus have also been found to exhibit semelparity with a distinct breeding season between the months of October through December.

[13] The dental arrangement for the species consists of large canine teeth but lack accessory cusps, correlating with the age and sex of the animal.

They have white or light gray ears and the females are unique due to the odd rusty-red color of their mammary area with seven nipples located on the abdominal region.