Kerodon rupestris (Wied-Neuwied, 1820)

Size and Weight

The rock cavy, Kerodon rupestris, is a fairly large rodent that can weigh up to 1 kilogram (2.2 pounds).

Tail Morphology

Like other cavy species, rock cavies have vestigial tails or no tails at all.

Coloration

Their backs are grey-brown, and their bellies range from tan to light brown.

Convergent Evolution

In both appearance and habit, they closely resemble the unrelated African rock hyraxes, an example of convergent evolution.

Diet Type

Rock cavies are herbivorous.

Feeding Habits

They feed on the seeds and leaves of the scrubby vegetation that grows within their territories; this vegetation includes tender leaves and certain species of creeper.

Habitat Preferences

Rock cavies inhabit dry, rocky areas with low, scrubby vegetation, and they prefer to live close to stony mountainsides and hills.

Native Distribution

They are native to eastern Brazil, ranging from eastern Piauí state to Minas Gerais state.

Introduced Range

They have also been introduced to the island of Fernando de Noronha, located off Brazil’s eastern coast.

Female Weight

Female rock cavies weigh between 700 and 800 grams.

Reproductive Output

They give birth to only one or two young per litter, but producing several litters each year is common.

Gestation and Birth Weight

The average gestation period for rock cavies is 75 days, and newborn rock cavies weigh approximately 90 grams.

Placenta Structure

The placenta of a rock cavy is similar to that of other hystricomorph rodents: it has several lobes lined with blood vessels that undergo counter-current blood flow.

Placental Blood Vessel Arrangement

Blood vessels from the mother run along the placenta, while vessels from the fetus run back over the mother’s vessels.

Placental Function

This arrangement allows for more efficient oxygen flow between the mother and the fetus.