Tetrapod-lines

308,000,000 before present, Walker County , Alabama

Cincosaurus cobbi Aldrich These tiny curved lines of small reptile (?) feet walked the earth long ago and got preserved in slate:

Ala.--More than 300 million years ago, nature froze time in its tracks here --- leaving a legacy of fossil footprints that paleontologists say is now one of the richest records of coal age life in the world. In the last three years, thin sheets of gray shale unearthed at the Union Chapel Coal Mine in Walker County have yielded thousands of perfectly preserved footprints of creatures that are older than the dinosaurs.