Here's a jokey challenge for this mod. Recolor the elephant to look like an American Mastodon, and recolor the Woolly Mammoth to look like an Asian Elephant. Just to be a little confusing and also for a bit of laughs.

Or if the Asian Elephant is too plain, just recolor the Mammoth into a Palaeoloxodon.

The Mastodon from the Elephant was definitely something I was going to do once I got around to toying with extinct animals, but I hadn't thought of any good ideas for what to do with the Mammoth. I like your ideas! Maybe I'll have to add a pair of pachyderms in a future update ;) Of course, any extinct animals I'll add I'll have to check with Dephesmo first - their Dino Dawn mod is perfect for extinct animals, and I don't want to step on any toes. If they don't plan on adding any of the animals I have in mind, I will happily add them myself!

Also, since there are only three official spiders (Black Widow, Garden and Tarantula), there are like thousands of options for new spiders to be made for this.

But I'll only go with these four just to make sure this mod doesn't get too overpopulated and redundant with spiders.

-Sydney Funnel-Web Spider (recolored from Tarantula) - Poison, Web Throwing, also known for having the strongest bite of any spider.
-Lynx Spider (recolored from Black Widow) - Web Throwing, Camoflague
-Wandering Spider (recolored from Garden Spider) - Poison, Leap Attack
-Mexican Redknee (recolored from Tarantula) - Disorientating Barbs, Digging?

Good choices! Spiders overall have a pretty similar body plan so I was definitely planning on adding a few, and I like how unique some of these are!

A rat would also be a good template for several rodent and insectivorous animals. A few unique ones I can think of would be:

-Solenodon (Poison)
-Opossum (Immunity)
-Bandicoot (..... No reason, but should it be light brown or orange?)

Another good template is the Komodo Dragon. You can basically make a ton of lizards and salamanders with that. For example:

-Water Monitor (Amphibious)
-Gila Monster (Poison, Camoflague)
-Giant Salamander (Amphibious)

Oh yeah, lizards will be super easy to pull from the komodo, most of them are similar enough in shape that they should work pretty well on the komodo dragon's model. The rat would also be a pretty good one to work with, the opossum was definitely one I was toying with adding. Ideally, I'd give it some kind of "play dead" ability, but adding new abilities to the game is incredibly difficult... the immunity seems like a decent compromise. I'll see what I can do!