Creationists make some valid points out of context, lol. For example, when we study the fossil record, we look at similar forms in simular locatiins placed in order of layers but we cannot lol verify one fossil is descended from another. (i confess, i dont know if DNA can be obtained from any fossils or not. I assume not.). I think
DNA can be extracted from very old biological material, though there is of course considerable degradation. Not fossils as such, but pollen trapped in ice cores, insects sealed in amber, mummified humans... Here's a wiki article on the topic:http://en.wikipedia.org/wiki/Ancient_DNA
And while maybe we can't definitively
verify descent from one fossil organism to its successors, in observed ancestral lineages like the various dinosaur species, whales, horses and humans, that's still the best explanation for the observed similarities within those lineages.