- Comparison of the frontal appendages of Peytoia with other members of Hurdiidae
- Morphology and movement range of the frontal appendage of Peytoia nathorsti
- Oral cone of Peytoia nathorsti in comparison to Anomalocaris and Hurdia
- Size diagram
Peytoia Temporal range: | |
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Fossil specimen of Peytoia nathorsti | |
Reconstruction of P. nathorsti | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | † Dinocaridida |
Order: | † Radiodonta |
Family: | † Hurdiidae |
Genus: | † Peytoia Walcott, 1911 |
Type species | |
†Peytoia nathorsti Walcott, 1911 | |
Species | |
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Synonyms | |
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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. [1] Its two frontal appendages had long bristle-like spines, it had no fan tail, and its short stalked eyes were behind its large head.
108 specimens of Peytoia are known from the Greater Phyllopod bed, where they comprise 0.21% of the community. [2]
Peytoia nathorsti and its junior synonym Laggania cambria played a major role in the discovery of the radiodont body plan. Initially interpreted as a jellyfish and a sea cucumber respectively, they were eventually shown to be the mouthparts and body of a single animal, which bore Anomalocaris -like appendages.
Peytoia infercambriensis is the geologically oldest known radiodont species. [1]
Peytoia belongs to the clade Hurdiidae, and is closely related to the contemporary genus Hurdia . [3]
Peytoia contains two named species: Peytoia nathorsti, the type species, from the Burgess Shale of Canada and the Wheeler and Marjum Formations of the United States, [4] and Peytoia infercambriensis from the Zawiszyn Formation of Poland. [1] Another species of Peytoia may be present in the Burgess Shale, represented by a single frontal appendage from the Tulip Beds locality. [5] A specimen regarded as Peytoia cf. nathorsti is known from the Balang Formation of China. [6]
The history of Peytoia is entangled with that of "Laggania" and Anomalocaris : all three were initially identified as isolated body parts and only later discovered to belong to one type of animal. This was due in part to their makeup of a mixture of mineralized and unmineralized body parts; the oral cone (mouth) and frontal appendage were considerably harder and more easily fossilized than the delicate body. [7]
The first was a detached frontal appendage of Anomalocaris, described by Joseph Frederick Whiteaves in 1892 as a phyllocarid crustacean, because it resembled the abdomen of that taxon. [7] The first fossilized oral cone was discovered by Charles Doolittle Walcott, who mistook it for a jellyfish and placed it in the genus Peytoia. In the same paper, Walcott described a poorly-preserved body specimen as Laggania; he interpreted it as a holothurian (sea cucumber). In 1978, Simon Conway Morris noted that the mouthparts of Laggania were identical to Peytoia, but interpreted this as indicating that Laggania was a composite fossil of Peytoia and the sponge Corralio undulata . [8] Later, while clearing what he thought was an unrelated specimen, Harry B. Whittington removed a layer of covering stone to discover the unequivocally connected arm thought to be a phyllocarid abdomen and the oral cone thought to be a jellyfish. [9] [7] Whittington linked the two species, but it took several more years for researchers to realize that the continuously juxtaposed Peytoia, Laggania and frontal appendage represented one enormous creature. [7] Laggania and Peytoia were named in the same publication, but Conway Morris selected Peytoia as the valid name in 1978, which makes it the valid name according to International Commission on Zoological Nomenclature rules. [8] [10]
The discovery that Anomalocaris, Laggania, and Peytoia represented parts of a single type of animal led to the synonymization of the three genera, with Peytoia nathorsti reclassified as Anomalocaris nathorsti. [11] Peytoia nathorsti was subsequently considered a junior synonym of Anomalocaris canadensis, while Laggania cambria became recognized as a distinct genus and species again, [12] but in 2012 it was determined that Anomalocaris canadensis had an oral cone with only three large plates, unlike that of Laggania cambria and Peytoia nathorsti with four, and Peytoia was once again recognized as valid, with Laggania its junior synonym. [10]
A second species, Peytoia infercambriensis , was named in 1975 as Pomerania infercambriensis. Its discoverer, Kazimiera Lendzion, interpreted it as a member of Leanchoiliidae, [13] a family which now known as part of the unrelated megacheirans (great appendage arthropods). It was subsequently renamed Cassubia infercambriensis because the name Pomerania had already been used for an ammonoid. [14] C. infercambriensis was later recognized as a radiodont. [15] It was later determined that the specimen was a composite of a radiodont frontal appendage and the body of an unknown arthropod. [1] Due to the close similarity of the appendage to Peytoia nathorsti, C. infercambriensis was reassigned to Peytoia. [1]
P. nathorsti had body length about 28.7–30.3 cm (11.3–11.9 in). [16] The oral cone of Peytoia nathorsti has four large plates, similar to Hurdia, as compared to three in Anomalocaris. However, unlike Hurdia, the oral cone of Peytoia lacks inner rows of spines. [17] The frontal appendages have 13 podomeres in their distal part, as is typical and likely ancestral for radiodonts. Like other hurdiid radiodonts, the frontal appendages have five blade-like endites, which have short auxiliary spines. An intercalary podomere is present, separating the proximal and distal ends of the appendage. The appendages also have large medial spines, sometimes referred to as "gnathites", which face towards the opposite appendage. [18] The trunk consists of 13 segments, which are associated with wide swimming flaps. Compared to Hurdia, Peytoia has less prominent setal blades. [19]
Phylogenetic position of Peytoia within Panarthropoda, according to Pates et al. (2022). [20]
It has been proposed that the frontal appendages of Peytoia were used to sift sediment for prey, however, some authors have considered this unlikely due to the small size and irregular spacing of the auxiliary spines. It has been alternatively proposed that Peytoia was a predator, using its appendages to capture slow-moving, relatively large benthic prey. [21]
Dinocaridida is a proposed fossil taxon of basal arthropods, which flourished during the Cambrian period and survived up to Early Devonian. 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.
Amplectobelua 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.
Anomalocarididae is an extinct family of Cambrian radiodonts, a group of stem-group arthropods.
Peytoia infercambriensis is a species of hurdiid radiodont in the genus Peytoia.
Schinderhannes bartelsi is a species of hurdiid radiodont (anomalocaridid), known from one specimen from the Lower Devonian Hunsrück Slates. Its discovery was astonishing because the latest definitive radiodonts were known only from the Early Ordovician, at least 66 million years earlier than this taxon.
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 later surviving members include the subfamily Aegirocassisinae from the Early Ordovician of Morocco and the Early Devonian member Schinderhannes bartelsi from Germany.
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.
Stanleycaris is an extinct, monotypic genus of hurdiid radiodont from the middle Cambrian (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. The genus was characterized by the rake-like frontal appendages with robust inner spines.
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, being the type species Caryosyntrips serratus.
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.
Aegirocassis 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 amounts of baleen-like auxiliary spines. This animal evolving filter-feeding traits was most likely a result of the Great Ordovician Biodiversification Event, when environmental changes caused a diversification of plankton, which in turn allowed for the evolution of new suspension feeding lifeforms. Alongside the closely related Pseudoangustidontus, an unnamed hurdiid from Wales, the middle Ordovician dinocaridid Mieridduryn, and the Devonian hurdiid Schinderhannes this radiodont is one of the few dinocaridids known from post-Cambrian rocks.
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. The type species, Ramskoeldia platyacantha, was discovered in the Chengjiang biota of China, the home of numerous radiodontids such as Amplectobelua and Lyrarapax.
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 Xianguang, who had discovered and named the type species Anomalocaris saron in 1995 along with his colleagues Jan Bergström and Per E. Ahlberg.
Titanokorys is a genus of extinct hurdiid (peytoiid) 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.
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.
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.
Cordaticaris is a genus of extinct hurdiid (peytoiid) radiodont that lived in what is now northern China during the middle Cambrian period. This animal was described in 2020 based on remains found in the Zhangxia Formation, located in the Shandong Province. It is differentiated from other members of its family by its unique heart-shaped frontal sclerite, and its frontal appendages bearing nine endites and seven more elongated subequal endites. This animal was important as it was the first Miaolingian aged hurdiid known from rock layers outside of laurentia, allowing paleontologists to get a better grasp of this families geographic range in life.
Buccaspinea is an extinct genus of Cambrian hurdiid radiodont from the Marjum Formation, known from frontal appendages and a nearly complete albeit headless specimen with a preserved oral cone. Buccaspinea was described in January 2021, being the second-most recent hurdiid genus to be described.