Ancient raindrop fossils reveal that we can thank greenhouse gases for early life on Earth

A raindrop is temporary, leaving behind a damp blotch and no more. Even if it falls in just the right area to create an imprint, even if that imprint is preserved for billions of years, it's just the imprint of a raindrop…right? Well, a fossilized footprint can teach archaeologists about the creatures who roamed the…