[Almost] Convergent Evolution?

Sorry, my entire knowledge of lizards could fit in a thimble, and I know squat about their behavior developments. However my attention was caught by your bringing up convergent evolution. This is a subject that I have always been curious about. For others who are not familiar with the term, it is the idea that very similar traits developed into two completely unrelated organisms. For example the bat wing and the bird wing are said to be convergent evolutionary traits. Likewise are the eyes and many other organs found in unrelated organisms.My question is how could two completely unrelated species, like your lizards, develop such similar traits? Or for another example, on the continent of Australia, the Tasmanian Wolf (now extinct) was every bit as much of a "wolf" as the North American Timber Wolf, with the exception it was marsupial. Yet the super continent is said to have broken up long before the arrival of this Australian species. So if it evolved on this isolated continent, which has no other indigenous dogs, what family did it evolve from?I mean suppose the genome of a species has about a million sites where a change of a single nucleotide could yield an advantage by natural selection. And these sites are spread through some ten thousand genes that each encode some ten thousand proteins. So there would have to be a hundred potential adaptive changes that could occur in each of ten thousand genes. This all means that any given species must have a lot of freedom in the way it evolves.Say it takes roughly 500 steps to lead to a new species. This would mean that in the first step there would be a million choices. After one occurred, there would then be a million choices in the next step, and in the third step and so on. If this occurred for the entire 500 steps, the process would have enormous freedom. If we were to start the process over (and the mutations are random), then the odds against it repeating the exact same path are a million times itself 500 times.My point is that if the mutations are truly random, and if at each step there are a million choices, then the chances of the same trait evolving twice should be impossible.

No but the mutations are (supposedly). I see.So if you and I both went to the train station (though we are starting from two different cities), and randomly started picking locations of travel, even though we both experienced the same weather and financial obligations etc... you are saying the likelihood is that with a million different choices at each rout that with in five hundred trips we would eventually both wind up at the same station, just by different routs?