Palaeoscolecid worms may be nematomorphs rather than annelids

Abstract

Lower Palaeozoic palaeoscolecid worms have usually been referred to the phylum Annelida, albeit often with a question-mark, The find of palaeoscolecids with armed proboscis in the Lower Cambrian Chengjiang fauna from Yunnan, southwest China, provides evidence that these worms were aschelminths. They are similar to the Nematoda, Priapulida, and Nematomorpha and presumably closest to the latter, although not parasitic. The palaeoscolecids appear to be just one of several ‘armoured-worm’ radiations among the earliest representatives of modem phyla, as suggested by the plentitude of ‘small shelly fossils’ in the Lower Cambrian. ***Aschelminthes, Cambrian, Chengjiang fauna, Nematomorpha, Palaeoscolecida.