Radiodonta

Anomalocaris (from Ancient Greek , meaning "unlike", and , meaning "shrimp", with the intended meaning "unlike other shrimp") is an extinct genus of radiodont, an order of early-diverging stem-group marine arthropods. It is best known from the type species A. canadensis, found in the Stephen Formation (particularly the Burgess Shale) of British Columbia, Canada. The other named species A. daleyae is known from the somewhat older Emu Bay Shale of Australia. Other unnamed Anomalocaris species are known from China and the United States.

Aegirocassis (″Aegir's helmet″) is an extinct genus of giant radiodont arthropod belonging to the family Hurdiidae that lived 480 million years ago during the early Ordovician in the Fezouata Formation of Morocco. It is known by a single species, Aegirocassis benmoulai. Van Roy initiated scientific study of the fossil, the earliest known of a "giant" filter-feeder discovered to date. Aegirocassis is considered to have evolved from early predatory radiodonts. This animal is characterized by its long, forward facing head sclerite, and the endites on its frontal appendages that bore copious amoun

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 were used for a variety of functions. Radiodonts were among the earliest large predators, and 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 memb

Anomalocarididae (occasionally mis-spelt Anomalocaridae) is an extinct family of Cambrian radiodonts, a group of stem-group arthropods.

devonian radiodont

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.

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.

Amplectobelua (meaning "embracing beast") is an extinct genus of late Early Cambrian amplectobeluid radiodont, a group of stem arthropods that mostly lived as free-swimming predators during the first half of the Paleozoic Era.

Stanleycaris ("Stanley's shrimp") is an extinct genus of hurdiid radiodont from the Cambrian (Stage 3 to Miaolingian). 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.

Hurdiidae (synonymous with the previously named Peytoiidae) is an extinct cosmopolitan family of radiodonts, a group of stem-group marine arthropods, which lived during the Paleozoic Era. It is the most long-lived radiodont clade, lasting from the Cambrian period to the Devonian period.

300px|left|thumb|Reconstruction of the head region of Cambroraster falcatus. A: Dorsal view, B: Ventral view, Ey: Eye, Fa: Frontal appendage, He:H-element, Bp: Bilobate posterior region, Lp: Posterolateral process, Oc: Oral cone, Pe: P-element, Pn: P-element neck Cambroraster is an extinct monotypic genus of hurdiid radiodont, dating to the middle Cambrian, and represented by the single formally described species Cambroraster falcatus. Hundreds of specimens were found in the Burgess Shale, and described in 2019. A large animal (for its era) at up to (but not as long as Titanokorys at ), it is

Titanokorys is a genus of extinct hurdiid (peytoiid) radiodont (a grouping of primitive stem arthropods which lived during the early Paleozoic) that lived during the Miaolingian epoch of the middle Cambrian. It is the largest member of its family from the Cambrian, with an estimated body length of around long, making it one of the largest animals of the time. It bears a resemblance to the related, and contemporary, genus Cambroraster. Fossils of T. gainesi were first found within the Marble Canyon locality of the Burgess Shale in 2018, however the fossils were not named until 2021 because they

Caryosyntrips ("nutcracker") is an extinct genus of stem-arthropod which known from Canada, United States and Spain during the middle Cambrian. It was first named by Allison C. Daley and Graham E. Budd in 2010, with the type species being Caryosyntrips serratus.

Houcaris is a possibly paraphyletic radiodont genus, tentatively assigned to either Amplectobeluidae, Anomalocarididae or Tamisiocarididae, known from Cambrian Series 2 of China and the United States. The type species is Houcaris saron which was originally described as a species of the related genus Anomalocaris. Other possible species include H. magnabasis and H. consimilis. The genus Houcaris was established for the two species in 2021 and honors Hou Xian-guang, who had discovered and named the type species Anomalocaris saron in 1995 along with his colleagues Jan Bergström and Per E. Ahlberg

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.

Lyrarapax is a radiodont genus of the family Amplectobeluidae that lived in the early Cambrian period 518 million years ago. Its fossils were found in the Maotianshan Shales of China. The first species, Lyrarapax unguispinus was described in 2014, with a second species, Lyrarapax trilobus being described in 2016, differing principally in the morphology of its frontal appendages.

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.

Paranomalocaris is a genus of radiodont recovered from the Cambrian Stage 4 aged Wulongqing Formation, eastern Yunnan. It contains two species, Paranomalocaris multisegmentalis and P. simplex. It is only known from its frontal appendage.

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.

genus of radiodonts

Pahvantia is an extinct genus of hurdiid radiodont from the Cambrian period. It is known by a single species, Pahvantia hastata, described from Wheeler Shale and Marjum Formation in Utah. Although it was once considered as a filter feeder based on the large number of putative setae on the frontal appendage, these structures were later interpreted as fossil material of the "trunk" section.

Pseudoangustidontus (meaning "false Angustidontus") is a genus of hurdiid (peytoiid) radiodont from the Lower Ordovician of Morocco. This genus includes two described species, '''Pseudoangustidontus duplospineus and Pseudoangustidontus izidigua', which both belong to the smaller Aegirocassisinae subfamily, however, a third unnamed species is also known. This animal is only known from the Fezouata Formation, a lower Ordovician fossil site in Morocco that is of Konservat-Lagerstätten status, meaning that the fossils from this site are exceptionally well preserved. This taxon was first described

Guanshancaris is an extinct genus of amplectobeluid radiodont known from the Cambrian Stage 4 Guanshan Biota of southern China. It is only known from a single species. G. kunmingensis which was described in 2013 as a species of Anomalocaris before being placed in a new genus in 2023. Like many other radiodonts, it is only known from fragmentary remains, including its frontal appendages and the oral cone. It has been suggested to have been durophagous. Based on the proportions of Anomalocaris, it is estimated to have been long.

Lenisicaris, from Latin lēnis, meaning "smooth", and Ancient Greek καρίς (karís), meaning "shrimp", is an extinct Cambrian anomalocaridid radiodont, known from the Maotianshan Shales of China and the Kinzers Formation of Pennsylvania.

Ramskoeldia is a genus of amplectobeluid radiodont described in 2018. It was the second genus of radiodont found to possess gnathobase-like structures (abbreviated as GLS) and an atypical oral cone after Amplectobelua. The type species, Ramskoeldia platyacantha, was discovered in the Chengjiang biota of China, the home of numerous radiodonts such as Amplectobelua and Lyrarapax.

Echidnacaris briggsi is an extinct species of radiodont known from the Cambrian Stage 4 aged Emu Bay Shale of Australia. Formerly referred to as "Anomalocaris" briggsi, it was placed in the new monotypic genus Echidnacaris in 2023. It is only distantly related to true Anomalocaris, and is instead placed in the family Tamisiocarididae.