Not a cat. Not a civet. This is a fossa (Cryptoprocta ferox), the largest of the native Malagasy carnivorans. Note the five-toed foot and lack of a dewclaw.
When is a civet not a civet?
When is a mongoose not a mongoose?
When they are found on Madagascar!*
Yeah. You know how Madagascar has all of these primitive strepsirrhine primates and has not a single monkey?
Well, something similar exists with the native Malagasy carnivorans.
Just as the various species of lemur represent a primitive branch of primate that evolved in isolation on the island of Madagascar, the native carnivorans of Madgascar all represent a relatively primitive lineage of feliformia. There are no cats or hyenas on Madagascar.
And Madagascar also does not have civets or mongooses.
However, these animals were all initially classified as civets and mongooses– simply because they share many traits with these animals that are found in Asia and the African mainland.
But these traits are actually superficial.
You see, civets and mongooses are primitive feliform carnivorans in the same way these animals are. But just because these animals share common traits does not mean necessarily that they are that closely related. Convergent and parallel evolution can make different lineages develop similar traits, and if we are talking about species that result from some particular ancient island biogeography, the insular forms might represent an entire branch that is no longer evident on the mainland.
In the case of these Malagasy carnivorans, the latter plays a much more important role.
Molecular analysis has revealed that all Malagasy carnivorans are more closely related to mongooses than civets, even though three species–the fossa, the falanouc, and the Malagasy civet– were classified in the civet family (Viverridae). It turns out that the ancestor of the Malagasy carnivorans split from the ancestors of modern mongooses during the Oligocene. At the time, there were no modern cats, but many of the ancestral feliforms had cat-like features and may have looked a lot like fossas. The two oldest species of Malagasy carnivora are the Malagasy civet and the fossa, so the common ancestor that came to Madagascar may have been more quasi-cat or civety than than modern mongooses (Herpestidae) are.
Ring-tailed mongoose (Galidia elegans) is not a mongoose. It likely evolved into a mongoose type via parallel evolution. Its ancestor was probably a more cat or civet-like ancestor. However, like all Malagasy carnivorans, it is more closely related to mongooses than civets.
Between 16 and 24 million years ago, the ancestral Malagasy carnivoran came to the island. There were no other carnivorans on Madagascar and through adaptive radiation, these animals came to fill the niches that are represented by mongooses, civets, and small cats in Africa and Asia.
Because these animals represent an ancient divergence from the mongoose family, they have since been given their own family within the order Carnivora. Now known as the Euplerids, these animal represent a very unique evolutionary line within the feliforms. They retain many primitive traits that are shared with hyenas, civets, mongooses, and cats. For example, the fossa looks a lot like a small puma and behaves very much like a cat, but it also has genitalia that has the spines that we find in cats and the pseudo penis we find in hyenas and binturongs (a type of civet).
In no other part of the world have primitive feliforms been able to establish themselves as the dominant predators. On the African and Asian continents, these feliforms are not dominant predators at all. The ancestral Malagasy carnivoran no longer exists in Africa. Cats and hyenas have become the dominant species from the feliform suborder. Madagascar represents what might have happened had the larger carnivorans never evolved and only the smaller primitive ones were given free reign.
In many ways, Madagascar is to placental mammals what Australia is to marsupials. It is a land before cats and hyenas, just as it is a land before monkeys.
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*There are actually several things that are called civets but are not. If it’s found in the New World, the civet usually refers to some species of spotted skunk (Spilogale) or the two species of procyonid that are in the genus Bassariscus, which do look a lot like genets, which are in the civet family. The African palm civet (Nandinia binotata) is now classifed in its own family, and it is considered basal of all feliform carnivorans. This palm civet will be featured in an upcoming post.
Interesting, everything I had seen/heard in the past about the fossa iindicated convergent evolution of a civet or mongoose to look/act more like a cat. But if I read you correctly, the truth is almost the opposite?
Yeah, It’s the opposite. The oldest lineage of Malagasy carnivorans is the fossa, the falanouc, and the Malagasy civet, and the fossa is said to be the oldest of the three. There were mongoose-cats running around Africa at the time these animals arrived in Madagascar.
The convergent evolution is between the Malagasy mongooses and those of Africa and Asia.
It the oldest lineages of these carnivorans are civety or cat-like, then it stands to reason that this is not exactly convergent evolution with the fossa and cats.
I think the initial hypothesis was they are convergent.
But fossa have several traits that none of these other animals have, but are shared with other unrelated feliforms.
The Fossa and Malagasy civet are the most basal forms.
As I’m often wont to say: “Humanity is most comfortable dealing with reality in binary terms, but reality is seldom, if ever, binary–its Boolean.”
Nature, and by extension, evolution, is obviously not binary. Its systematic but not simple–shades of gray vice black & white. Once again biologists need to readjust their mindsets & stretch their models to encompass new sets of conditional statements.