Myriapods (from Ancient Greek μυρίος (muríos) 'countless' and πούς (poús) 'foot') are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes.

[6][7] Other early myriapod fossil species around the similar time period include Kampecaris obanensis and Archidesmus sp.

[12] Malpighian tubules excrete nitrogenous waste into the digestive system, which typically consists of a simple tube.

[12] During mating, male myriapods produce a packet of sperm, or spermatophore, which they must transfer to the female externally; this process is often complex and highly developed.

Myriapods are most abundant in moist forests, where they fulfill an important role in breaking down decaying plant material,[2] although a few live in grasslands, semi-arid habitats or even deserts.

Although not generally considered dangerous to humans, many millipedes produce noxious secretions (often containing benzoquinones) which in rare cases can cause temporary blistering and discolouration of the skin.

[20] Under the Mandibulata hypothesis, Myriapoda is the sister taxon to Pancrustacea, a group comprising the Crustacea and Hexapoda (insects and their close relatives).

[21] A 2020 study found numerous characters of the eye and preoral region suggesting that the closest relatives to crown myriapods are the extinct Euthycarcinoids.

There are around 3,300 species,[23] ranging from the diminutive Nannarrup hoffmani (less than 12 mm or 1⁄2 in in length)[25] to the giant Scolopendra gigantea, which may exceed 30 centimetres (12 in).

[29][30][31] Their eggs, which are white and spherical and covered with small hexagonal ridges, are laid in batches of 4 to 25 at a time, and usually take up to 40 days to hatch.

The most famous members are from the genus Arthropleura, which was a giant, probably herbivorous, animal that could be up to 2.63 metres (8 ft 8 in) long,[34] but the group also includes species less than 1 cm (0.39 in).

[35][36] A variety of groupings (clades) of the myriapod classes have been proposed, some of which are mutually exclusive, and all of which represent hypotheses of evolutionary relationships.