Cowiedesmus is an extinct millipede genus described from Scotland,[1] and is considered as earliest known land animals alongside Pneumodesmus from same formation.
[2] It is originally considered that it is from the middle Silurian, a 2017 study suggested that the geological formation it contains actually appears to be from the Early Devonian (Lochkovian) instead.
[3] Although a 2023 study confirmed the age identification of the 2004 study through palynological, palaeobotanical and ziron analyses incorporating newly discovered additional data,[4] this is based on adjacent structurally separated block with different stratigraphy and sedimentology to the block with fossil site it was discovered, and it is confirmed as unsustainable.
[5] Cowiedesmus was about 4 cm (1.6 in) long and characterized by a greatly enlarged pair of legs on the 8th segment which may have been used in clasping females or functioned as gonopods (modified legs used to insert sperm during mating).
[1] The name Cowiedesmus references the Cowie Formation, a geological formation at Cowie Harbor, near the village of Stonehaven, Scotland, where the fossil was found and desmus, a common root word in millipede nomenclature meaning "bond" or "bridge".