Temporal range: Late Silurian
|Photomicrograph of the type specimen|
Wilson & Anderson, 2004 
Pneumodesmus newmani is a species of millipede that lived , in the Late Silurian. It is the first myriapod, and the oldest known creature to have lived on land. It was discovered in 2004, and is known from a single specimen from Stonehaven, Aberdeenshire, Scotland.
Discovery and naming
The fossil of P. newmani was found by Mike Newman, a bus driver and amateur palaeontologist from Aberdeen, in a layer of sandstone rocks on the foreshore of Cowie, near Stonehaven. The species was later given the specific epithet "newmani" in honour of Newman. The holotype is kept in National Museum of Scotland, Edinburgh. The genus name derives from the Greek pneumato ("air" or "breath") and desmus ("band", a common millipede root word) in reference to the inferred air-breathing habit.
The single, 1 cm-long fragment of P. newmani depicts small paranota (keels) high on the body, long, slender legs. The dorsal portion of each body segment is ornamented with a horizontal bar and three rows of roughly hexagonal bosses (bumps).
The fossil is important because its cuticle contains openings which are interpreted as spiracles, part of a gas exchange system that would only work in air. This makes P. newmani the earliest documented arthropod with a tracheal system, and indeed the first known oxygen-breathing animal on land.
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 millipede, and has been dated to (late Wenlock epoch to early Ludlow epoch). The earliest centipedes follow some 10 million years later, and the first known vertebrate on land, Tiktaalik, is 50 million years younger than Pneumodesmus.
- Heather M. Wilson & Lyall I. Anderson (2004). "Morphology and taxonomy of Paleozoic millipedes (Diplopoda: Chilognatha: Archipolypoda) from Scotland". Journal of Paleontology 78 (1): 169–184. doi:10.1666/0022-3360(2004)078<0169:MATOPM>2.0.CO;2.
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- Paul Selden & Helen Read (2008). "The oldest land animals: Silurian millipedes from Scotland" (PDF). Bulletin of the British Myriapod & Isopod Group 23: 36–37.
- Rowland Shelley & Paul Marek (March 1, 2005). "Millipede Fossils". East Carolina University. Archived from the original on May 27, 2011.
- David Winter (April 9, 2006). "When animals first conquered the land". Science and sensibility.
- "Cowie". BBC Scotland. Retrieved May 6, 2007.