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''Peytoia'' is a genus of
hurdiid Hurdiidae (synonymous with the previously named Peytoiidae) is an extinct cosmopolitan distribution, cosmopolitan Family (biology), family of radiodonts, a group of Crown group#Stem groups, stem-group marine arthropods, which lived during the Pal ...
radiodont 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 ...
, an early diverging order of stem-group
arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...
s, that lived in the
Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...
period, containing two species, ''Peytoia nathorsti'' from the
Miaolingian The Miaolingian is the third Series of the Cambrian Period, and was formally named in 2018. It lasted from about to million years ago and is divided in ascending order into 3 stages: the Wuliuan, Drumian, and Guzhangian. The Miaolingian is prec ...
of Canada and ''
Peytoia infercambriensis ''Peytoia infercambriensis'' is a species of Hurdiidae, hurdiid radiodont in the genus ''Peytoia''. ''P. infercambriensis'' is the geologically oldest known radiodont; its remains date to the Cambrian Stage 3, third age of the Cambrian. The typ ...
'' from Poland, dating to
Cambrian Stage 3 Cambrian Stage 3 is the still unnamed third stage of the Cambrian. It succeeds Cambrian Stage 2 and precedes Cambrian Stage 4, although neither its base nor top have been formally defined. The plan is for its lower boundary to correspond approxima ...
. Its two frontal appendages had long
bristle A bristle is a stiff hair or feather (natural or artificial), either on an animal, such as a pig, a plant, or on a tool such as a brush or broom. Synthetic types Synthetic materials such as nylon are also used to make bristles in items such as b ...
-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 The Phyllopod bed, designated by USNM locality number 35k, is the most famous fossil-bearing member of the Burgess Shale fossil ''Lagerstätte''. It was quarried by Charles Walcott from 1911–1917 (and later named Walcott Quarry), and was ...
, where they comprise 0.21% of the community. ''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 Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animal ...
and a
sea cucumber Sea cucumbers are echinoderms from the class (biology), class Holothuroidea ( ). They are benthic marine animals found on the sea floor worldwide, and the number of known holothuroid species worldwide is about 1,786, with the greatest number be ...
respectively, they were eventually shown to be the mouthparts and body of a single animal, which bore ''
Anomalocaris ''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 fro ...
''-like appendages. ''Peytoia infercambriensis'' is the geologically oldest known radiodont species.


Classification

''Peytoia'' belongs to the clade
Hurdiidae Hurdiidae (synonymous with the previously named Peytoiidae) is an extinct cosmopolitan distribution, cosmopolitan Family (biology), family of radiodonts, a group of Crown group#Stem groups, stem-group marine arthropods, which lived during the Pal ...
, and is closely related to the contemporary genus ''
Hurdia ''Hurdia'' is an extinct genus of Hurdiidae, hurdiid radiodont that lived 505 million years ago during the Cambrian Period. Fossils have been found in North America, China, and the Czech Republic. Taxonomic history ''Hurdia'' was named in 1912 ...
''. ''Peytoia'' contains two named species: ''Peytoia nathorsti'', the
type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
, from the
Burgess Shale The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest fos ...
of Canada and the Wheeler and
Marjum Formation The Marjum Formation is a Cambrian geological formation that overlies the Wheeler Shale in the House Range, Utah. It is named after its type locality, Marjum Pass, and was defined in 1908. The formation is known for its occasional preservation of ...
s of the United States, and ''
Peytoia infercambriensis ''Peytoia infercambriensis'' is a species of Hurdiidae, hurdiid radiodont in the genus ''Peytoia''. ''P. infercambriensis'' is the geologically oldest known radiodont; its remains date to the Cambrian Stage 3, third age of the Cambrian. The typ ...
'' from the Zawiszyn Formation of Poland. Another species of ''Peytoia'' may be present in the Burgess Shale, represented by a single frontal appendage from the Tulip Beds locality. A specimen regarded as ''Peytoia'' cf. ''nathorsti'' is known from the
Balang Formation The Balang formation, is a Cambrian, Cambrian Period geological formation, which outcrops in western Hunan and eastern Guizhou in southern China. It contains Burgess Shale-type preservation, Burgess Shale-type soft-bodied fossils. It is intermedi ...
of China.


History

The history of ''Peytoia'' is entangled with that of "''Laggania''" and ''
Anomalocaris ''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 fro ...
'': 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
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
ized than the delicate body. The first was a detached frontal appendage of ''Anomalocaris'', described by
Joseph Frederick Whiteaves Joseph Frederick Whiteaves (December 26, 1835 – August 8, 1909), was a British palaeontologist. Born in Oxford, Whiteaves was educated at private schools, and afterwards worked under John Phillips at Oxford (1858–1861); he was led to st ...
in 1892 as a
phyllocarid Phyllocarida is a subclass of crustaceans, comprising the extant order Leptostraca and the extinct orders Hymenostraca and Archaeostraca. This clade of marine crustaceans diversified extensively during the Ordovician The Ordovician ( ) is a ...
crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
, because it resembled the abdomen of that taxon. The first fossilized oral cone was discovered by
Charles Doolittle Walcott Charles Doolittle Walcott (March 31, 1850February 9, 1927) was an American paleontologist, administrator of the Smithsonian Institution from 1907 to 1927, and director of the United States Geological Survey. He is famous for his discovery in 19 ...
, who mistook it for a
jellyfish Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animal ...
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 cucumbers are echinoderms from the class Holothuroidea ( ). They are benthic marine animals found on the sea floor worldwide, and the number of known holothuroid species worldwide is about 1,786, with the greatest number being in the Asia†...
(sea cucumber). In 1978,
Simon Conway Morris Simon Conway Morris (born 1951) is an English palaeontologist, evolutionary biologist, and astrobiologist known for his study of the fossils of the Burgess Shale and the Cambrian explosion. The results of these discoveries were celebrated ...
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''. 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. 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. ''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 The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries. Orga ...
rules. 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''. ''Peytoia nathorsti'' was subsequently considered a junior synonym of ''Anomalocaris canadensis'', while ''Laggania cambria'' became recognized as a distinct genus and species again, 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. A second species, ''
Peytoia infercambriensis ''Peytoia infercambriensis'' is a species of Hurdiidae, hurdiid radiodont in the genus ''Peytoia''. ''P. infercambriensis'' is the geologically oldest known radiodont; its remains date to the Cambrian Stage 3, third age of the Cambrian. The typ ...
'', was named in 1975 as ''Pomerania infercambriensis''. Its discoverer, Kazimiera Lendzion, interpreted it as a member of Leanchoiliidae, a family which now known as part of the unrelated
megacheira Megacheira ("great hands", also historically great appendage arthropods) is an extinct class of predatory arthropods defined by their possession of spined "great appendages". Their taxonomic position is controversial, with studies either consider ...
ns (great appendage arthropods). It was subsequently renamed ''Cassubia infercambriensis'' because the name ''Pomerania'' had already been used for an ammonoid. ''C. infercambriensis'' was later recognized as a
radiodont 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 ...
. It was later determined that the specimen was a composite of a radiodont frontal appendage and the body of an unknown arthropod. Due to the close similarity of the appendage to ''Peytoia nathorsti'', ''C. infercambriensis'' was reassigned to ''Peytoia''.


Description

''P. nathorsti'' had body length about . 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. 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. The trunk consists of 13 segments, which are associated with wide swimming flaps. Compared to ''Hurdia'', ''Peytoia'' has less prominent setal blades.


Phylogeny

Phylogenetic position of ''Peytoia'' within Panarthropoda, according to Pates ''et al''. (2022).


Ecology

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 The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...
prey.


See also

*
Paleobiota of the Burgess Shale This is a list of the Biota (ecology), biota of the Burgess Shale, a Cambrian lagerstätte located in Yoho National Park in Canada. The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is fa ...


References


External links

* {{Taxonbar, from=Q20672130 Burgess Shale fossils Cambrian arthropods Radiodonta Fossil taxa described in 1911