Monotypic prehistoric protostome genera

Diania is an extinct genus of lobopodian panarthropod found in the Lower Cambrian Maotianshan shale of China, represented by a single species - D. cactiformis. Known during its investigation by the nickname "walking cactus", this organism belongs to a group known as the armoured lobopodians, and has a simple worm-like body with robust, spiny legs. Initially, the legs were thought to have a jointed exoskeleton and Diania was suggested to be evolutionarily close to early arthropods, but many later studies have rejected this interpretation.

Odontogriphus (from , 'tooth' and , 'riddle') is a genus of soft-bodied animals known from middle Cambrian Lagerstätte. Reaching as much as in length, Odontogriphus is a flat, oval bilaterian which apparently had a single muscular foot and a "shell" on its back that was moderately rigid but of a material unsuited to fossilization.

Myoscolex is an early animal known from the Cambrian Emu Bay Shale in South Australia. It is of unknown affinity but has been interpreted as an annelid and as an arthropod close to Opabinia. Myoscolex is the earliest known example of phosphotized muscle tissue, and as to which shows distinct annulation.

left|thumb|248x248px|Fossil specimen, Geological Museum of China Cardiodictyon is a genus of lobopodian known from 518 millions years old Chengjiang Lagerstätte. 525 millions years old partial fossil is also reported. It has ~25 pairs of legs, each associated with a pair of dorsal plates.

Antennacanthopodia is a small lobopodian from the Chengjiang biota that dates to about 520 million years ago (Cambrian Stage 3). It is similar to the extant Onychophora (velvet worm) and is the only widely accepted stem-onychophoran lobopodian from the Cambrian period. Antennacanthopodia had nine pairs of stubby legs, a pair of potential ocelli, and two pairs of antennae. The first pair of antennae were much longer than the second and are still present in modern onychophorans. The identity of the smaller antennae are less clear, but they might be homologous with either the slime papillae or on

Cucumericrus ("cucumber-leg") is an extinct genus of stem-arthropod. The type and only species is Cucumericrus decoratus, with fossils discovered from the Maotianshan Shales of Yunnan, China.

Jianshanopodia is a monotypic genus of Cambrian lobopodian, discovered in the Maotianshan Shales of Yunnan, China.

Sialomorpha dominicana, also known as the mold pig, is a panarthropod genus of uncertain affinities discovered in 30-million year old Dominican amber by George Poinar at Oregon State University and Diane R. Nelson at East Tennessee University. It was placed in a new genus and family (Sialomorphidae) unto itself, and appears to represent a new phylum. S. dominicana shares some resemblance to tardigrades and mites. It is about 100 μm long and grew by molting its exoskeleton. It was probably an omnivore, feeding on minute invertebrates and fungi, including mold.

Louisella is a genus of worm known from the Middle Cambrian Burgess Shale. It was originally described by Charles Walcott in 1911 as a holothurian echinoderm, and represents a senior synonym of Miskoia, which was originally described as an annelid. 48 specimens of Louisella are known from the Greater Phyllopod bed, where they comprise < 0.1% of the community. It has been stated to have palaeoscolecid-like sclerites, though this is not in fact the case.

Helenodora is an extinct basal onychophoran or lobopodian genus known from the Carboniferous Carbondale Formation of Illinois. The only known species described is H. inopinata. The ecology of this animal is not well known, but it is thought that it may have lived on land and/or underwater.

Megadictyon is a genus of Cambrian lobopodian with similarities to Jianshanopodia and Siberion. The name of the genus is occasionally mis-spelt as Magadictyon.

Cricocosmia is an abundant palaeoscolecid worm endemic to the Early Cambrian Chengjiang Biota of Yunnan, China. It resembles modern priapulids, and holds a pivotal role in understanding the evolution of early ecdysozoans. It possessed paired lateral sclerites and paired ventral projections which have been compared with early panarthropod legs. It was a detritivore, living in shallow horizontal burrows, sometimes in great concentration.

Eximipriapulus is a genus of priapulid-like organisms, perhaps belonging to the crown group, known from the Chengjiang biota.