Lobopodians are members of the informal group Lobopodia, or the formally erected phylum Lobopoda Cavalier-Smith (1998). They are panarthropods with stubby legs called lobopods, a term which may also be used as a common name of this group as well. While the definition of lobopodians may differ between literatures, it usually refers to a group of soft-bodied, marine worm-like fossil panarthropods such as Aysheaia and Hallucigenia. However, other genera like Kerygmachela and Pambdelurion are often referred to as “gilled lobopodians”.
Hallucigenia is a genus of lobopodian known from Cambrian aged fossils in Burgess Shale-type deposits in Canada and China, and from isolated spines around the world. The generic name reflects the type species' unusual appearance and eccentric history of study; when it was erected as a genus, H. sparsa was reconstructed as an enigmatic animal upside down and back to front. Lobopodians are a grade of Paleozoic panarthropods from which the velvet worms, water bears, and arthropods arose.
Opabinia regalis is an extinct, stem group arthropod found in the Middle Cambrian Burgess Shale Lagerstätte of British Columbia. Opabinia was a soft-bodied animal, measuring up to 7 cm in body length, and its segmented trunk had flaps along the sides and a fan-shaped tail. The head shows unusual features: five eyes, a mouth under the head and facing backwards, and a clawed proboscis that probably passed food to the mouth. Opabinia probably lived on the seafloor, using the proboscis to seek out small, soft food. Fewer than twenty good specimens have been described; 3 specimens of Opabinia are known from the Greater Phyllopod bed, where they constitute less than 0.1% of the community.
Marrella is an extinct genus of marrellomorph arthropod known from the Middle Cambrian of North America and Asia. It is the most common animal represented in the Burgess Shale of British Columbia, Canada, with tens of thousands of specimens collected. Much rarer remains are also known from deposits in China.
Canadaspis is an extinct genus of bivalved Cambrian arthropod, known from North America and China. They are thought to have been benthic feeders that moved mainly by walking and possibly used its biramous appendages to stir mud in search of food. They have been placed within the Hymenocarina, which includes other bivalved Cambrian arthropods.
Habelia is a genus of extinct arthropod from the Middle Cambrian, thought to be one of the earliest known relatives of chelicerates. Its fossils have been found in the Burgess Shale in British Columbia, Canada. Fifty-four specimens of Habelia are known from the Greater Phyllopod bed, where they comprise 0.1% of the community.
Primicaris is genus of Cambrian arthropod from the Chengjiang biota of China and the Burgess Shale of Canada. It contains a single described species, P. larvaformis.
Radiodonta is an extinct order of stem-group arthropods that was successful worldwide during the Cambrian period. Radiodonts are distinguished by their distinctive frontal appendages, which are morphologically diverse and used for a variety of functions. Radiodonts are among the earliest large predators, but they also included sediment sifters and filter feeders. Some of the most famous species of radiodonts are the Cambrian taxa Anomalocaris canadensis, Hurdia victoria, Peytoia nathorsti, Titanokorys gainesi, Cambroraster falcatus and Amplectobelua symbrachiata. The later surviving members include the subfamily Aegirocassisinae from the Early Ordovician of Morocco and the Early Devonian member Schinderhannes bartelsi from Germany.
Stanleycaris is an extinct genus of hurdiid radiodont from the Cambrian. The type species is Stanleycaris hirpex. Stanleycaris was described from the Stephen Formation near the Stanley Glacier and Burgess Shale locality of Canada, as well as Wheeler Formation of United States. A second species, S. qingjiangensis is known from the Qingjiang biota of China. The genus was characterized by the rake-like frontal appendages with robust inner spines.
The Luolishaniidae or Luolishaniida are a group of Cambrian and Ordovician lobopodians with anterior 5 or 6 pairs of setiferous lobopods. Most luolishaniids also have posterior lobopods each with a hooked claws, and thorn-shaped sclerites arranged as three or more per trunk segment. The type genus is based on Luolishania longicruris Hou and Chen, 1989, from the Chengjiang Lagerstatte, South China. They are presumed to have been benthic suspension or filter feeders.
Collinsium was a genus of lobopodian from the Early Cambrian. It is represented by a single fossil species, Collinsium ciliosum, found in the Xiaoshiba Lagerstätte of China. Similar to the later Hallucigenia it was a small worm-like creature with spikes along its back and feeding tentacles near its head. Unlike Hallucigenia, Collinsium had 9 walking appendages and 6 fine anterior appendages. Its body was covered in hair-like papillae and its fine anterior appendages were lined with setae. The generic name honors paleontologist Desmond Collins.
Ovatiovermis is a genus of filter-feeding lobopodian known from the Burgess Shale. Like many lobopodians, it had nine pairs of lobopods (legs). It was well adapted to filter-feeding and probably did so from the nearest high vantage point.
Collinsovermis is a genus of extinct panarthropod belonging to the group Lobopodia and known from the middle Cambrian Burgess Shale in British Columbia, Canada. It is monotypic having only one species, Collinsovermis monstruosus. After its initial discovery in 1983, Desmond H. Collins popularised it as a unique animal and was subsequently dubbed "Collins' monster" for its unusual super armoured body. The formal scientific description and name were given in 2020. A similar lobopodian is known from the Emu Bay Shale, however it remains unnamed.
Acinocricus is a genus of extinct panarthropod belonging to the group Lobopodia and known from the middle Cambrian Spence Shale of Utah, United States. As a monotypic genus, it has one species Acinocricus stichus. The only lobopodian discovered from the Spence Shale, it was described by Simon Conway Morris and Richard A. Robison in 1988. Owing to the original fragmentary fossils discovered since 1982, it was initially classified as an alga, but later realised to be an animal belonging to Cambrian fauna.
Luolishania is an extinct genus of lobopodian panarthropod and known from the Lower Cambrian Chiungchussu Formation of the Chengjiang County, Yunnan Province, China. A monotypic genus, it contains one species Luolishania longicruris. It was discovered and described by Hou Xian-Guang and Chen Jun-Yuan in 1989. It is one of the superarmoured Cambrian lobopodians suspected to be either an intermediate form in the origin of velvet worms (Onychophora) or basal to at least Tardigrada and Arthropoda. It is the basis of the family name Luolishaniidae, which also include other related lobopods such as Acinocricus, Collinsium, Facivermis, and Ovatiovermis. Along with Microdictyon, it is the first lobopodian fossil discovered from China.
Thanahita is a genus of extinct lobopodian and known from the middle Silurian Herefordshire Lagerstätte at the England–Wales border in UK. It is monotypic and contains one species, Thanahita distos. Discovered in 2018, it is estimated to have lived around 430 million years ago and is the only known extinct lobopodian in Europe, and the first Silurian lobopodian known worldwide.
Hallucigeniidae is a family of extinct worms belonging to the group Lobopodia that originated during the Cambrian explosion. It is based on the species Hallucigenia sparsa, the fossil of which was discovered by Charles Doolittle Walcott in 1911 from the Burgess Shale of British Columbia. The name Hallucigenia was created by Simon Conway Morris in 1977, from which the family was erected after discoveries of other hallucigeniid worms from other parts of the world. Classification of these lobopods and their relatives are still controversial, and the family consists of at least four genera.
Lenisambulatrix is a genus of extinct worm belonging to the group Lobopodia and known from the Lower Cambrian Maotianshan shale of China. It is represented by a single species L. humboldti. The incomplete fossil was discovered and described by Qiang Ou and Georg Mayer in 2018. Due to its missing parts, its relationship with other lobopodians is not clear. It shares many structural features with another Cambrian lobopodian Diania cactiformis, a fossil of which was found alongside it.
Pahvantia is an extinct genus of hurdiid radiodont from the Cambrian. It is known by a single species, Pahvantia hastata, described from Wheeler Shale and Marjum Formation in Utah. Although it was once considered as filter feeder using large number of putative setae, this structures are later considered as misidentification of trunk materials.
Surusicaris is an extinct genus of bivalved arthropod, known from the Cambrian Burgess Shale of British Columbia, Canada. It is considered to be closely related to Isoxys, and like it has spined grasping frontal appendages.
