Grammar

Perhaps you're just not recognising how bad the creationist arguments are ? They are plausible people, but on investigation a lot of what they say disintegrates.No, the fact that a few groups show relatively little change is not a great problem. While sharks as a groups have been around for a long time, the species still change. But why should sharks change beyond recognition ? Despite being descended from four-legged land breathers icthyosaurs and dolphins still have evolved to a shark-like form. So why shouldn't sharks stay much the same ? They "haven't missed the boat" in any way - they've done very well.

You may have seen Jaws but there were even more fearsome sharks in the distant past (whale sharks are bigger than Great Whites, but much less aggressive) HomeThis page has a collection of fossil sharks teeth for sale. Note how the older species are generally extinct.http://www.megalodonteeth.com/html/misccat.htmlIf you want something more detailed, here is a key to identifying fossil shark teeth http://www.nmnh.si.edu/paleo/sharkteeth/

I hope this is not going into too much detail.Can we take two fossils of different species and say that one is the ancestor of another ?Well for a start we can't say that the individual animals were ancestor and descendant. The best we can manage is that the species are related as ancestor and descendant.Often we don't have the fine-grained record that would allow us to say even that the species of the later fossil is the descendant of the older fossil. Sometimes we do, but usually we don't.So usually we are restricted to saying that the older fossil is either the ancestral species or closely related to the ancestral species of the more recent fossil.

Tell you what Mike, why don't you pick out an example of the data "creation scientists" say points to a "young age" and start a thread to discuss it ?I suggest you choose one that is easy to understand so that we don't end up having to rely heavily on "duelling experts".