About Darwinian evolution, you're partially right but evolution is not quite that narrow. New species might beat old ones in one environment, but in another environment the old ones may be better able to survive. I.E under different "rules".

Ehhhh........not really, Stormy. Evolution is dependant on the environment in question, so to say that something may do better in another environment is specious logic. Things "evolve" to best suit the environment they exist in. Darwin actually proved that evolution is quite "narrow" (specific).

Well I kind of see what you mean so look at it this way, say a species evolves and is better able to survive then the older form, the older form starts dying out of course. The new form grows and survives, being fitter.

Now the environment could change in a way that makes the newer species less fit, and the older species will start to grow again and the other one will start to die out. Or less likely but possible, another species could come in that is able to trounce the newer one but not the older one.

Look at human vs ape evolution, we got smarter but a lot weaker physically. Are we better able to survive? Well the first forms of humans werent at all better able to survive, they barely got by and then eventually we got smart enough that we became better able to survive than most anything else.

An evolutionary adaption isnt necessairly good either, it may not effect the species and their ability to survive or may negatively impact their ability to survive, it's a somewhat blind process. They may evolve and not really be any "fitter" just different, and just happen to survive and outlast other forms for other reasons.

One other point, an older species doesnt necessairly have to completely die out, often they are mostly wiped out but survive in small numbers and might later make a resurgence in the cases I mentioned.
So again I say you're partially right. Within an environment a species generally adapts and is then fitter although in another environment the older species may be fitter, but things within an environment can change making an older species the fitter one again. I'd say that this is why we have so many similar forms of animals rather than a few vastly different ones in our world. Thats purely speculation though.
Member of DaJoGen MMA school under Dave Hagen and Team Chaos fight team under Denver Mangiyatan and Chris Toquero, ran out of Zanshin Martial Arts in Salem Oregon: http://www.zanshinarts.org/Home.aspx,