Sidneyia is an extinct arthropod known from fossils found from the Early to the Mid Cambrian of China and the Mid Cambrian Burgess Shale of British Columbia, Canada.
Dinocaridida is a proposed fossil taxon of basal arthropods that flourished in the Cambrian period with occasional Ordovician and Devonian records. Characterized by a pair of frontal appendages and series of body flaps, the name of Dinocaridids refers to the suggested role of some of these members as the largest marine predators of their time. Dinocaridids are occasionally referred to as the 'AOPK group' by some literatures, as the group compose of Radiodonta, Opabiniidae, and the "gilled lobopodians" Pambdelurion and Kerygmachelidae. It is most likely paraphyletic, with Kerygmachelidae and Pambdelurion more basal than the clade compose of Opabiniidae, Radiodonta and other arthropods.
Anomalocaris is an extinct genus of radiodont, an order of early-diverging stem-group arthropods.
Peytoia is a genus of hurdiid radiodont, an early diverging order of stem-group arthropods, that lived in the Cambrian period, containing two species, Peytoia nathorsti from the Miaolingian of Canada and Peytoia infercambriensis from Poland, dating to Cambrian Stage 3. Its two frontal appendages had long bristle-like spines, it had no fan tail, and its short stalked eyes were behind its large head.
Anomalocarididae is an extinct family of Cambrian radiodonts, a group of stem-group arthropods.
Kerygmachela kierkegaardi is a kerygmachelid gilled lobopodian from the Cambrian Stage 3 aged Sirius Passet Lagerstätte in northern Greenland. Its anatomy strongly suggests that it, along with its relative Pambdelurion whittingtoni, was a close relative of radiodont and euarthropods. The generic name "Kerygmachela" derives from the Greek words Kerygma (proclamation) and Chela (claw), in reference to the flamboyant frontal appendages. The specific name, "kierkegaardi" honors Danish philosopher Søren Kierkegaard.
Parapeytoia is a genus of Cambrian arthropod. The type and only described species is Parapeytoia yunnanensis, lived over 518 million years ago in the Maotianshan shales of Yunnan, China. Unidentified fossils from the same genus also had been discovered from the nearby Wulongqing Formation.
Peytoia infercambriensis is a species of hurdiid radiodont in the genus Peytoia.
A number of assemblages bear fossil assemblages similar in character to that of the Burgess Shale. While many are also preserved in a similar fashion to the Burgess Shale, the term "Burgess Shale-type fauna" covers assemblages based on taxonomic criteria only.
Isoxys is a genus of extinct bivalved Cambrian arthropod; the various species of which are thought to have been freely swimming predators. It had a pair of large spherical eyes, and two large frontal appendages used to grasp prey.
Radiodonta is an extinct order of stem-group arthropods that was successful worldwide during the Cambrian period. They may be referred to as radiodonts, radiodontans, radiodontids, anomalocarids, or anomalocaridids, although the last two originally refer to the family Anomalocarididae, which previously included all species of this order but is now restricted to only a few species. Radiodonts are distinguished by their distinctive frontal appendages, which are morphologically diverse and used for a variety of functions. Radiodonts included the earliest large predators known, 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 gainessii, Cambroraster falcatus and Amplectobelua symbrachiata, the Ordovician Aegirocassis benmoulai and the Devonian Schinderhannes bartelsi.
Hurdia is an extinct genus of hurdiid radiodont that lived 505 million years ago during the Cambrian Period. Fossils have been found in North America, China and the Czech Republic.
Kiisortoqia soperi is an extinct species of arthropod from the Early Cambrian Sirius Passet Lagerstätte in Greenland. While it had a superficially trilobite-like bodyform, it also possessed large frontal appendages similar to those of radiodonts.
Tamisiocarididae is a family of radiodonts, extinct marine animals related to arthropods, that bore finely-spined appendages that were presumably used in filter-feeding. When first discovered, the clade was named Cetiocaridae after a speculative evolution artwork, Bearded Ceticaris by John Meszaros, that depicted a hypothetical filter-feeding radiodont at a time before any were known to exist. However, the family name was not valid according to the International Code of Zoological Nomenclature, as no real genus named "Cetiocaris" exists, and in 2019 it was formally replaced by the name Tamisiocarididae, after the only valid genus of the clade at the time. The family is only known from Series 2 of the Cambrian, unlike other radiodont families, which persisted longer into the Cambrian. All known species would have lived in tropical or subtropical waters, suggesting a preference for warmer waters.
Amplectobeluidae is a clade of Cambrian radiodonts. It currently includes five definitive genera, Amplectobelua, Lyrarapax, Ramskoeldia, Guanshancaris and a currently unnamed genus from the lower Cambrian aged Sirius Passet site in Greenland. There is also a potential fifth genus, Houcaris, but that genus has become problematic in terms of its taxonomic placement.
Hurdiidae is an extinct cosmopolitan family of radiodonts, a group of stem-group arthropods, which lived during the Paleozoic Era. It is the most long-lived radiodont clade, lasting from the Cambrian period to the Devonian period.
Ramskoeldia is a genus of amplectobeluid radiodont described in 2018. It was the second genus of radiodont found to possess gnathobase-like structures and an atypical oral cone after Amplectobelua. It was discovered in the Chengjiang biota of China, the home of numerous radiodontids such as Amplectobelua and Lyrarapax.
Titanokorys is a genus of extinct hurdiid radiodont that existed during the mid Cambrian. It is the largest member of its family from the Cambrian, with a body length of 50 cm (20 in) long, making it one of the largest animals of the time. It bears a resemblance to the related genus Cambroraster. Fossils of T. gainesi were first found within Marble Canyon in 2018. The fossils were not named until 2021 because they were assumed to be giant specimens of Cambroraster.
Erratus is an extinct genus of marine arthropod from the Cambrian of China. Its type and only species is Erratus sperare. Erratus is likely one of the most basal known arthropods, and its discovery has helped scientists understand the early evolution of arthropod trunk appendages. Some of the stem-arthropods like radiodonts did not have legs, instead they had flap like appendages that helped them swim. Erratus on the other hand had not only flaps but also a set of primitive legs. It also supported the theory that the gills of aquatic arthropods probably evolved into the wings and lungs of terrestrial arthropods later in the Paleozoic.
Laminacaris is a genus of extinct stem-group arthropods (Radiodonta) that lived during the Cambrian period. It is monotypic with a single species Laminacaris chimera, the fossil of which was described from the Chengjiang biota of China in 2018. Around the same time, two specimens that were similar or of the same species were discovered at the Kinzers Formation in Pennsylvania, USA. The first specimens from China were three frontal appendages, without the other body parts.
