Millipede
Evolution

Millipedes are among the first animals to have colonised land during the Silurian period. Early forms probably ate mosses and primitive vascular plants. There are two major groups of millipedes whose members are all extinct: the Archipolypoda ("ancient, many-legged ones") which contain the oldest known terrestrial animals, and Arthropleuridea, which contain the largest known land invertebrates. Pneumodesmus newmani is the earliest member of the millipedes from the late Wenlock epoch of the late Silurian around 428 million years ago, or early Lochkovian of the early Devonian around 414 million years ago, known from 1 cm (1 ⁄ 2 in) long fragment and has clear evidence of spiracles (breathing holes) attesting to its air-breathing habits. Other early fossils of millipedes are Kampecaris obanensis and Archidesmus sp. from 425 millions years ago in the late Silurian. During the Upper Carboniferous (340 to 280 million years ago), Arthropleura became the largest known land-dwelling invertebrate on record, reaching lengths of at least 2 m (6 + 1 ⁄ 2 ft). Millipedes also exhibit the earliest evidence of chemical defence, as some Devonian fossils have defensive gland openings called ozopores. Millipedes, centipedes, and other terrestrial arthropods attained very large sizes in comparison to modern species in the oxygen-rich environments of the Devonian and Carboniferous periods, and some could grow larger than one metre. As oxygen levels lowered through time, arthropods became smaller.
keywords:existence