Pneumodesmus newmani

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Pneumodesmus newmani Fossil range: Silurian
Photomicrograph of the type specimen
Conservation status
Fossil
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Subphylum: Myriapoda Class: Diplopoda Order: Cowiedesmida Family: Cowiedesmidae Genus: Pneumodesmus Species: P. newmani
Binomial name
Pneumodesmus newmani Wilson & Anderson, 2004 [1]

Pneumodesmus newmani is a species of millipede that lived 428 million years ago ^[1][2]. It was discovered in 2004, and is known from a single specimen which is held in a museum in Stonehaven, Aberdeenshire, Scotland. It is the oldest known creature to have lived on land.^[3]

[edit] Discovery

The single, 1 cm-long fragment 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 ^[4]. The species was later given the specific epithet "newmani" in honour of Newman.

[edit] Significance

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 arthropod with a tracheal system, and indeed the first oxygen-breathing animal on land ^[5].^[3]

Ichnofossils of myriapods are known dating back to the late Ordovician, but P. newmani is the earliest body fossil of a millipede, and has been dated to 428 mya (late Wenlock epoch to early Ludlow epoch). The earliest centipedes follow some 10 million years later ^[5], and the first vertebrate on land, Tiktaalik, is 50 million years younger than Pneumodesmus ^[6]. During the Silurian, the rocks that would later be part of Scotland were being laid down on the continent of Laurentia, in a tropical part of the Southern Hemisphere ^[7].

[edit] References