scsj asked: All this talk about the moa foot has me wondering - even with modern technology, would it be possible to preserve something like a (real) dinosaur foot for that many millions of years? Or do we even have any way of knowing that?

This is a really compelling question that I’ve been sitting on for a while.  I really have no idea.  I would think it would be possible to freeze dry the tissue (a process which evaporates frozen moisture ensuring longevity of soft tissues).  Another technique that could work would be cryopreservation, where cells are submerged in sub-zero temperatures usually by dipping them in vats of liquid nitrogen.  But as far as knowing how long these things last — they are relatively recent preservation techniques so the entire span of integrity hasn’t been adequately tested.  Species frozen in icebergs or glaciers have lasted tens of thousands of years — like the baby mammoth which is dated about 40,000 years old — but as far as millions of years?  I’m really unsure.  You could get all Jurassic Park and assume that it’s possible to extract DNA out of species encased in amber, but… is the preservation of small samples of DNA the same thing as preserving the entire limb of a creature?  I’d argue that the majority of the limb will break down.