The Not-So-Terrible Mouse

The pacarana (Dinomys branickii, hence its sometime appellation: "terrible mouse") or Branick's rat is one of the largest living rodents on the planet (after capybaras and some beavers). Its name is derived from a Tupi Indian term meaning "false paca" due to a resemblance to that large rodent. It is the only living member of the family Dinomyidae. While known to the indigenous people of the regions they inhabit, the pacarana was first described to science 1973.

Far from being a "terrible" creature, the pacarana is generally calm and non-aggressive. The animal would only fight as a last resort. They have been variously described as looking like large guinea pigs, spineless porcupines, or "an immense rat well advanced in development toward a bear" ( The fur is from dark brown to blackish and they have discontinuous white stripes along the length of the back with some rows of white spots on either side. The upper lip is deeply cleft and they have long, grey whiskers. Pacaranas have a largish head and small ears. They have strong claws on each four-toed paw.

Length (body): 73 cm-79 cm (28.7"-31.1")
Length (tail): 19 cm (7.4")
Weight: 10-15 kg (22-33 pounds)

Pacaranas live in the area of the lower slopes and valleys of the Andes (elevations of 240-2000 m/800'-6600'), generally between Colombia and Bolivia (have also been found in Brazil, Ecuador, Peru and Venezuela). They seem to be pretty rare and have been thought extinct more than once. It might be due to a certain lack of information on the creature due to its habitat.

A primarily nocturnal animal, the pacarana has a diet that consists fruits, leaves, and plant stems (how ferocious). Like many other rodents, it often eats while sitting back on its hind legs and holding the food in its fore paws. It shelters in crevices, enlarged by digging, though there is some dispute over how much actual digging the animals do since they have not been seen to do so in captivity. On the other hand they do not seem to use those claws much for climbing, either (more questions that require further study of this rare mammal).

They have also a "system of communication" that is made up of combinations of stomping the fore paws, chattering their teeth, "whines, songs, and hisses" (

Pacaranas are sometimes solitary, but are often found in pairs with their litters. In captivity, it has been observed that their gestation period lasts 222-283 days. It's bit long for a rodent—compare with the golden hamster which has a gestation of 16-18 days—but larger rodents tend to have longer periods (yet the two larger members of the order, the capybara and beaver, only have a period between 100-150 days).

The mother typically gives birth to one or two young, weighing around 900 g (about 2 pounds). It isn't clear on the specifics of sexual maturity and though the births have been observed in January and February and pregnancies in February and May, it isn't yet known what the "birth season" is for sure. Pacaranas that have been observed mating have been seen to "cry" in order to attract mates.

In captivity, pacaranas have been known to live up to nine years. Their primary threat comes from native people who hunt them for food.