What were the First Animals to Walk on Land?
The first animals to walk on land are unknown. There is evidence that soft-bodied arthropods and slug-like animals visited the land as far back as 510 million years ago, in the Cambrian era, leaving behind mysterious tracks called Climactichnites and Diplichnites. These tracks are mysterious because no fossils have been found of the animals that made them. Some of these trace fossils are as wide as four inches. Perhaps these animals did not actually breathe air, and only slimed along on land for short periods as a way of moving from pond to pond. According to scientific consensus, the first verified land animal was a one-centimeter myriapod. Present-day examples of myriapods include millipedes and centipedes. This myriapod, discovered in 2003 in Scotland and named Pneumodesmus newmani, is dated to 428 million years ago. Paleontologists can tell it lived on land because its fossil shows it possessed spiracles; holes that insects, spiders, rays, and sharks use for breathing air. Prior to
