The fossa (Cryptoprocta ferox) lurks in the shadows of Madagascar’s forests and is the island’s largest carnivorous mammal. This elusive hunter has the body shape of a small cougar but belongs to a Malagasy carnivore family more closely related to mongooses.

An adult fossa has a head-and-body length of 70 to 80 cm (28 to 31 in), with a tail adding 65 to 70 cm (26 to 28 in), bringing total length to nearly 1.5 m (almost 5 ft). Males usually weigh 5.5 to 8.6 kg (12 to 19 lb), and large individuals can reach 10 to 12 kg (22 to 26 lb).

The fur is short and dense, typically reddish-brown to chocolate, sometimes darker. It has a dog-like snout, rounded ears, and forward-facing eyes that give good depth perception for moving between branches. Sensitive whiskers act like feelers, helping it detect obstacles and prey in dim light. The tail works as a counterbalance while climbing and sprinting through the canopy.

Fossas belong to Eupleridae, a carnivore family found only in Madagascar. Genetic studies suggest all Malagasy carnivores descended from a single ancestor that reached the island about 18 to 20 million years ago and then diversified into different ecological roles. Madagascar once had a larger, now-extinct relative, the giant fossa (Cryptoprocta spelea), about 20% bigger than today’s species.