> "According to evolution something like that should have not gone extinct so how does evolution explain its extinction?"
Are you trying to apply the phrase "survival of the fittest" and concluding that large predators must be the most fit? That's not how it works. That phrase applies to competition within a population. The idea is that some individuals within a population will tend to have heritable advantages over others (given a particular environment and ecological niche) and will thus leave more descendants. So eventually the entire population will consist of individuals with those advantages. It doesn't apply to interactions BETWEEN species, except in the rare occasions that two species are both trying to occupy the same ecological niche in the same place. So just because a given individual of species A can chomp up a given individual of species B, that doesn't mean species A will continue and species B will go extinct.
You should also keep in mind that even in situations involving competition within a population, a heritable advantage isn't always associated with the ability to chomp up one's rivals. If you could beat me in a fight, but I can avoid you and can find food more easily than you, then I might end up leaving more descendants than you do. It all depends on which advantages have the best *fit* with the environment and niche.
> "When I took Chemistry we were taught that a theory is usually higher in science than a law because it has been proven beyond any contradiction that cannot be accounted for by experimental error."
Nope and nope. Scientific theories are explanations. Scientific laws are descriptions (often mathematical descriptions) of recurring phenomena. Either can be wrong, and neither one is more likely to be true. Scientists tend to appreciate theories over laws because they appreciate explanations, so in that sense they might be called "higher", but not in the sense of being more correct.
And you can't "prove" either a theory or a law. All you can do is use them to make predictions, and then test the predictions against the evidence. The more often the predictions turn out to be correct, the more likely is the theory or law to be true.
> "Evolution is more like a hypothesis than a theory."
No, it's a successful and generally accepted theory. Like all scientific theories, the theory of evolution must make predictions that are testable. So what does the theory predict we should find, and do we actually find it?
First of all, the theory predicts we should see examples of populations of one species evolving into new species. Do we? Yes we do. http://www.talkorigins.org/faqs/faq-speciation.html
http://en.wikipedia.org/wiki/Ring_species
Secondly, the theory predicts the existence of a Tree of Life. The Tree of Life is a family tree, of which every single living thing that has ever existed on the planet is a member. The existence of the Tree of Life (if true) would mean that the differences between living things would be organized into a nested hierarchy, such that two recently separated species would share numerous characteristics, of which a portion would also be shared by all species sharing a more distant common ancestor, of which a portion would also be shared by all species sharing an even more distant common ancestor; and so on. The Tree’s existence would also mean that two species branching from a common ancestor should be located in places that populations of the ancestor could have reached. It also means that the fossils we find should fit into the general pattern of hierarchical similarity, location, and timeframe established by the Tree. Finally, the hierarchical patterns of similarity established by present and past species on the Tree should be roughly the same regardless of whether we are comparing morphological characteristics, or genes, or non-coding DNA, or endogenous retroviruses, or proteins. We say “roughly the same” rather than “exactly the same” because various processes such as convergent evolution or fluctuating population sizes can somewhat throw off the hierarchical patterns established by the different traits being compared.
So what do we find? The Tree of Life is continually vindicated by study after study. Morphologically, humans are most similar to other apes, and some of those similarities are shared by monkeys, and some of those are shared by all primates, and some of those are shared by all mammals, and so on. We could as easily find the same treelike pattern starting from house finches, or from any other species. Comparisons of DNA sequences confirm and provide additional information regarding the treelike organization shown by morphological comparisons. http://www.sciencedaily.com/releases/2006/03/060303111420.htm Independently derived models of the tree tend to converge and reinforce one another, including models based on many different DNA sequences http://www.talkorigins.org/faqs/comdesc/section1.html#independent_convergence , models based on endogenous retroviruses http://www.talkorigins.org/faqs/comdesc/section4.html#retroviruses , and models based on fossils http://anthropology.si.edu/humanorigins/ha/a_tree.html . Essentially, wherever we look, however we look, the Tree is there.
If the Tree is real we would also expect to find at least some examples of fossil species that could have been common ancestors of major branches, and we’d expect to find them in specific geological strata. We do in fact find them, and they are where they ought to be. http://www.talkorigins.org/faqs/comdesc/section1.html#morphological_intermediates http://www.newscientist.com/article/dn14952-missing-link-fossil-stuck-its-neck-out.html?feedId=online-news_rss20
These are just a few basic predictions of the theory of evolution and some of the evidence supporting them. See here for some more: http://www.talkorigins.org/faqs/comdesc/ . Then ask yourself, what testable predictions does creationism make, and what evidence (if any) supports those predictions.