Philosophy of Biology: Very Old Eggs Reveal A Fast, Changing Path Through Evolution:
BIOLOGISTS STUDYING how species change over the eons have always been hampered by the little problem of previous generations of a species being, well, dead. Sure, you can infer something about what a creature was like from fossils, but fossils generally fail to preserve much except bone. As a result, some of an animal's most interesting features vanish into the dust of time.
But these days, not even death is forever. A few years ago, biologist W. Charles Kerfoot was examining "cores" -- basically, muck deposited decades earlier -- in a Michigan lake. Lo and behold, he and his colleagues discovered eggs, and not just any eggs. They had been laid long ago by tiny creatures (mostly insects and crustaceans) that no longer lived in the lake. Even better, there was still life in the eggs. Under the right conditions, they would hatch.
Testing evolutionary hypotheses.