Are there any of these models still available somewhere?

the geometry of the last lizard is located in a2p1-data.pak (there are few files there, you can find it by simply trying them one by one), I don't know about the others

The last one reminded me of the Beast, although its size is unclear. The Nagas are interesting, and that model with the bow too (it could be a level 2 archer from the Fortress faction in Heroes 3).