#eupleridae

Fossa (Cryptoprocta ferox) pups, family Eupleridae, endemic to most of Madagascar (but not found in the central part of the island).

Giant-striped Vontsira aka Grenedier's Mongoose (Galidictis grandidieri), family Eupleridae, Parc National de Tsimanampetsotsa, Madagascar

ENDANGERED.

YOU HAVE SELECTED ONE OF MY FAVORITE ANIMALS!!!

Fossa (Cryptoprocta ferox), family Eupleridae, endemic to most of Madagascar (but not found in the central part of the island).

Carnivorous, feeding on wide variety of other animals.

Not closely related to any animals on the African mainland (or anywhere else), Fossas are in the Madagascan Mongoose family (also called the Madagascan Carnivorans).

The closest living group to this family are the mongooses.

They have semi-retractable claws, they can extend them but not fully retract them.

The generic name Cryptoprocta, means "hidden anus", as the anus is hidden within the anal pouch.

The male's penis is external, unlike other members of this family. (They also have a baculum, a penis bone).

Active mostly late at night, early in the morning, or in late afternoon (sleeping during the hottest parts of the day).

The are FUCKING LOUD, especially when interacting with each other in social disputes or during mating.

there’s a lot to unpack with this one! first, let’s address the referenced insular gigantism. while it is true that some animals have been observed growing larger in island populations than their mainland counterparts, the exact opposite is also seen quite often!

insular dwarfism, or the tendency for island populations to adopt smaller body sizes than their mainland counterparts, has been observed in quite a few animal groups, from hadrosaurs to wooly mammoths to modern tigers!

islands often make great safe havens for small prey animals, who can grow much larger on islands since they aren’t being preyed upon! no need to hide under cover if there isn’t anyone hunting you, so the extinct nurulagus rex of the medditeranean was free to grow as big and as awkward as it pleased.

however, islands also present several challenges in the growth department, the two most pressing being 1. food availability and 2. space.

a massive animal needs both a lot of food and a lot of space, especially if it’s territorial and doesn’t get along well with others. islands obviously don’t have a whole lot of either of those things compared to mainland habitats, which essentially nerfs larger animals that want to squeeze in. (this is doubly true for carnivores, as big predators who can’t fly run the risk of eating everything on the island too quickly and starving themselves out!)

here’s a great video by PBS Eons about insular dwarfism in colombian mammoths: https://youtu.be/dXwoKEDtdlM?si=SiJDO3ylMYzJT177

that is to say, if fossas got much bigger, they run the risk of either starving due to lack of sufficient biomass to support their existence, or hunting all the lemurs to extinction (starving but with extra steps).

for the fossa specifically, we also need to look at its ecology. fossas are highly arboreal, just like their preferred prey. most of their lives, including hunting, takes place up in the trees. there is definitely a maximum feasible size for an animal whose weight is constantly supported by branches alone, and who needs to be able to navigate quickly through the canopy to catch lemurs.

all of this might be a moot point, though, since fossas weren’t always this size!

the very recently extinct cryptoprocta spelea, or the giant fossa, could have weighed between 35-45lbs (modern fossa max out at about 20lbs). that’s about the size of the smallest living big cat, the clouded leopard. local anecdotes claim it was even bigger; the rumored “black fossa” is said to reach 70lbs! it’s very likely that, if this larger fossa variant is extinct, it is linked to the recent extinction of the giant lemurs. larger predators need larger prey, and so once their big prey was gone, the giant fossa may have just withered away.

they might not be gone, though! this paper goes about documenting recent sightings of giant fossa and how they might indicate a potential lazarus taxon: https://par.nsf.gov/servlets/purl/10317033

Madagascar is full of unique animals, from the smallest insects all the way to the top of the food chain! Fossas occupy their own special family, Eupleridae, and feature plenty of special physical traits. One such trait is their sexual growth: from ages 1-2, female fossa undergo a process called transient masculinization, wherein they develop an enlarged clitoris resembling a penis and secrete an orange substance that colors their underside in the same pattern as the male's scrotum sac. These developments fade with age, and don't impede reproduction in any way.

Fossa (Cryptoprocta ferox), juveniles, family Eupleridae, endemic to most of Madagascar (but not found in the central part of the island).

Fossa (Cryptoprocta ferox), family Eupleridae, endemic to most of Madagascar (but not found in the central part of the island).