A 450 million year old sandstone core from the Ordovician Period could contain many things, but probably nothing with fur or feet. At a time when most of the northern hemisphere was covered entirely by ocean, fish ruled the day. The world's first vertebrates were evolving but not all of them had managed to develop jaws, much less a claw or a flippered foot to make the long crawl onto land. That would take another 100 million years or so. Give or take a million.

The Wagner Free Institute of Science
of Philadelphia, PA

11.02.16