Trace fossils of myriapods are known dating back to the late Ordovician (the geologic period preceding the Silurian), but "P. newmani" is the earliest body fossil of a myriapod, and has been dated to between (Silurian, late Wenlock epoch to early Ludlow epoch) and (Early Devonian (Lochkovian)). There are also trigonotarbid and arachnid fossils dating to around this time known from Lludlow in Shropshire, and together these comprise the oldest known air-breathing terrestrial animals. The earliest centipedes follow some 10 million years later, and the first known vertebrate on land, "Tiktaalik", dates from 50 million years later than "Pneumodesmus".