Why are so many Caniforms in Arctoidea?

[Domino Quartz]

Why are so many of the Caniforms in the clade Arctoidea? I know that "Arctoid" sort of means "bear-oid", so are species in the clade Arctoidea that closely related to bears? Also, how did this happen, from an evolutionary perspective?

[hamishspence]

It would appear that the clade Arctoidea was designed to cover all caniforms "more closely related to bears than to dogs" - to be the sister clade to dogs.

[Cespenar]

Isn't that in reverse? That there are Arctoidae in Caniformia? Which is kinda sensible, because Caniformia is not "dogs" per se, but all "dog-like"s, including bears.

[hamishspence]

I think they might have been making the point that Arctoidia is a huge clade within Caniformia (and a very diverse one - bears, weasels, seals, etc).

The only non-Arctoid caniforms, are canids (dogs, foxes, wolves, etc), and amphicyonids "bear-dogs".

[Eldan]

It seems the basal Arctoid is sort of weasel- or marten-like, actually. And tree-dwelling. The aquatic or large predatory forms came later.

And honestly, the answer to "why is there so many of these" is usually just "because they work well". Small arboreal predator seems to be a good niche that isn't covered much otherwise, while medium-sized land predator is a pretty common niche.

[Lvl 2 Expert]

And honestly, the answer to "why is there so many of these" is usually just "because they work well". Small arboreal predator seems to be a good niche that isn't covered much otherwise, while medium-sized land predator is a pretty common niche.

Plus smaller animals, or maybe rather animals of which you can feed more individuals per square kilometer of nature, tend to just have more species. There are approximately 633 species of primate (https://www.ippl.org/gibbon/blog/how-many-primates-are-there/) of which 8 are great apes (https://en.wikipedia.org/wiki/Ape) (including humans). That's not a fair comparison, you're comparing two equally old branches while I'm comparing one small branch with its parent, but the basic idea is similar: smaller species are more numerous.

For another example: there are around 5,000 species of mammals versus 10,000 species of birds and another 5,000 of amphibians, 4,000 of which are frogs. Not to mention beetles, which conservative estimates put at around 500,000.

[Domino Quartz]

Thanks for your answers.