Madagascar's top predator looks like a cat but is closer to mongooses
The fossa resembles a small cougar, climbs down trees head first and eats mostly lemurs, yet it is no cat. Taxonomists bounced it between cats, civets and mongooses for over 150 years until genetic studies showed that all of Madagascar's carnivores descend from a single colonising ancestor.
Found only on Madagascar, the fossa is the island's largest living mammalian carnivore. Adults measure 70 to 80 cm from nose to rump, with a tail almost as long again, and weigh roughly 5.5 to 8.6 kg, the males heavier. Its claws extend but never fully retract, and its remarkably flexible ankles let it grip trunks to descend head first or leap between trees; captive youngsters have swung upside down from ropes by their hind feet. More than half its diet is lemurs, supplemented by tenrecs, rodents, lizards and birds, and it hunts both day and night.
Edward Turner Bennett described the species in 1833 and filed it with the civets. In 1939 two scientists moved it into the cat family, and in 1945 George Gaylord Simpson moved it back, admitting it looked very feline. A 1993 DNA study pointed to mongooses. In 2003 Anne Yoder and colleagues showed all native Malagasy carnivores form one group, now the family Eupleridae, whose closest relatives are African and Asian mongooses; carnivores probably reached the island only once, about 18 to 20 million years ago. Its cat-like teeth, skull and gut are a case of convergent evolution driven by a diet of pure meat.
Biology offers oddities too. Young females go through a temporary masculinisation from about one to two years old, developing enlarged genital structures that later shrink; no other mammal is known to reverse such a feature as it grows, and hormones do not appear responsible. One idea is that it spares juveniles harassment from adult males or aggression from territorial females. Its genus name, Cryptoprocta, refers to a hidden anus tucked inside a scent pouch.
Bigger relatives once roamed the island: Cryptoprocta spelea, estimated at 10 to 20 kg, and Cryptoprocta bevatabe, described in 2026, at around 27 to 43 kg. Malagasy people recognise black, off-white and reddish kinds of fossa, and it is unclear whether these are folklore, individual variation or hidden species. Listed as vulnerable, the fossa is widely feared and often protected by local taboo, but habitat loss is its greatest threat.
Source: Fossa (animal)
