I made the mistake of requesting the alias of non-mammal_anus to anus, by following some commenter's instructions.
Please bring back the tag non-mammal_anus and just implicate anus to it, as it doesn't apply to every non-mammal with an anus.
It only applies to when a non-mammal has a mammal anus, which is not all of them.
This is from the direct wiki-page:

External mammalian anus on any non-mammalian species, such as reptiles, fishes, birds, and insects.

So it does have a purpose just like non-mammal_breasts, non-mammal_balls, and non-mammal_nipples do.

An anus is an anus. Non-mammals can have anuses, unlike non-mammal_breasts which indicates there are breasts on a non-mammal which don't otherwise have them. Anuses aren't exclusive to mammals, so a tag like non-mammal_anus would be like having a non-avian_claws tag. Any distinction in real non-mammalian anuses versus a mammalian anuses would be practically impossible to maintain with art, as people will just go, "anus? check. non-mammal? check. so, non-mammal_anus." irrespective of the style of anus.

watsit said:
An anus is an anus. Non-mammals can have anuses, unlike non-mammal_breasts which indicates there are breasts on a non-mammal which don't otherwise have them. Anuses aren't exclusive to mammals, so a tag like non-mammal_anus would be like having a non-avian_claws tag. Any distinction in real non-mammalian anuses versus a mammalian anuses would be practically impossible to maintain with art, as people will just go, "anus? check. non-mammal? check. so, non-mammal_anus." irrespective of the style of anus.

But, there is a visible difference between normal_anus and mammal_anus on the posts. Examples:
post #3554860
Just anus
post #110462
non-mammal_anus
post #3387916
Just anus
post #817951
non-mammal_anus
post #1402975
Just anus
post #179407
non-mammal_anus

There is enough of a difference that non-mammal_anus should remain as a tag.

There is enough of a difference that non-mammal_anus should remain as a tag.

Err, be brought back as a tag.

cow_of_fire said:
But, there is a visible difference between normal_anus and mammal_anus on the posts. Examples:
[...]
There is enough of a difference that non-mammal_anus should remain as a tag.

I honestly can't tell the difference you're trying to point out. I highly doubt enough people would be able to either for the tag to be remotely usable. And that's ignoring the fact that most people will go non-mammal + anus = non-mammal_anus, as they do with non-mammal_breasts and a number of other tags.

If you can identify a difference, then I believe it would be best for you to create a more specific tag that highlight that difference. non-mammal is vague, better tag which species_anus it is instead, or how the anus look.

m3g4p0n1 said:
If you can identify a difference, then I believe it would be best for you to create a more specific tag that highlight that difference. non-mammal is vague, better tag which species_anus it is instead, or how the anus look.

Oh...like equine_anus and canine_anus...
That is a good idea!
Thank you!

cow_of_fire said:
Oh...like equine_anus and canine_anus...
That is a good idea!
Thank you!

I believe canine_anus was made redundant and aliased away to anus? See alias #15981 & topic #21160.