IUCN list the species as critically endangered: it is affected by feral cats, climate change, and the clearing of forest in its potential range in coastal Colombia.

On 24 December 1898, Herbert Huntingdon Smith identified the first specimen of Santamartamys in Ocana, Santa Marta, Magdalena, Colombia.

[2] A second specimen, also of undetermined sex, was discovered in around 1913 in the Sierra Nevada de Santa Marta by Carriker, but there is not much information regarding its location either, or the date of discovery.

[9] The facial portion of the skull is very short, and the distance between the incisors and the molars is slightly less than the length of the coronary surface of its upper row of teeth.

[2] Santamartamys is a nocturnal rodent,[5] and its diet is unknown, but it is assumed to feed on plant matter such as fruits or seeds, like similar species in family Echimyidae.

[6] Due to the location's isolation and specific geological and climatic conditions, this mountainous region has high levels of biodiversity and endemism.

[1] Known as the "red-crested tree rat",[1] this species was originally described as Isothrix rufodorsalis by American biologist Joel Asaph Allen in 1899,[11] and was transferred to genus Diplomys in 1935 by George Henry Hamilton Tate.

[2] The genus name Santamartamys comes from "Santa Marta", part of the name of the location where the specimens were found, and mys, meaning "mouse".

[2][22] Set up on 31 March 2006, this reserve covers 1,024 ha (2,530 acres) at an altitude between 950 and 2,600 m (3,120 and 8,530 ft), and contains a large number of endemic or endangered species.

[1] Much of its potential area is infested with feral cats (who feed on fauna),[3][7] and climate change is a long-term threat to the species.