Stanleycaris Temporal range: | |
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Reconstruction of S. hirpex | |
Fossil specimens of S. hirpex | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | † Dinocaridida |
Order: | † Radiodonta |
Family: | † Hurdiidae |
Genus: | † Stanleycaris |
Species: | †S. hirpex |
Binomial name | |
†Stanleycaris hirpex Pates, Daley & Ortega-Hernández (2018) | |
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 [1] and Burgess Shale locality of Canada, [2] as well as Wheeler Formation of United States. [3] The genus was characterized by the rake-like frontal appendages with robust inner spines. [4] [2]
Stanleycaris was originally described only from frontal appendages and oral cone. [3] However, in 2022, 268 specimens of Stanleycaris, many of which were complete, were studied, making Stanleycaris a well documented radiodont. [2] Stanleycaris had three eyes, a bizarre configuration previously unknown among other radiodont genera; yet this head anatomy supports early differentiation among arthropod head and trunk segmentation. [2]
The original description of the taxon appeared in an online supplement to the article published by Jean-Bernard Caron, Robert R. Gaines, M. Gabriela Mángano, Michael Streng and Allison C. Daley in 2010. [1] That description did not satisfy of the requirements of the International Code of Zoological Nomenclature, as the Code did not accept taxa named in electronic publications as validly named until 2012; [3] the name was eventually validated by Pates, Daley & Ortega-Hernández (2018). [5]
Its generic name means "Crab of Stanley Glacier"; hirpex, L. "large rake", reflects the rake-like nature of its spiny frontal appendages. [1]
Stanleycaris was a small radiodont, with whole body specimen measured around 1 to 8.3 centimetres (0.39 to 3.27 in), excluding the tail. Even based on the largest, 3 centimetres (1.2 in)-long isolated frontal appendage, the upper body length was thought to be less than 20 centimetres (7.9 in) long. [2] Unlike most hurdiids with large head and broad neck region, the body of Stanleycaris was streamlined like those of anomalocaridids and amplectobeluids. [2]
The small head occupies about 15% of the total body length. Each lateral compound eye was estimated to have around 1000 ommatidia. In addition of a pair of stalked lateral eyes, a third, large median eye was located behind its preocular sclerite (H-element). Similar structures were evident in the fossils of Peytoia and Lyrarapax , suggesting these genera possibly had a median eye too. [2] Contrary to the agreement around mid and late 2010s (based on the discovery of Lyrarapax since 2014) suggest radiodonts had only protocerebrum on their cerebral ganglion, [6] The neuroanatomical evidence of Stanleycaris suggests radiodonts have both protocerebrum and deutocerebrum, and circumesophageal connective that surround digestive system between them. [2] Unlike other radiodonts, the paired lateral sclerites (P-element) are not evident in any Stanleycaris specimens, suggesting they were exclusively absent in this genus. [2]
The 1 to 3 centimetres (0.39 to 1.18 in)-long frontal appendages are the most commonly found component of this genus. It comprise 14 segments (podomeres) with 5 long, rake-like curved blades (endites) protruding from the ventral surface of podomere 3–7, while podomere 2 and 9 have short endites. [4] The upper surface bore a row of inner-facing, mostly forked robust spines (gnathites) which are unique to this genus. [4] Similar to Peytoia , the distal podomeres have claw-like dorsal and terminal spines. [4]
The mouth was surrounded by a tetraradial oral cone, which comprises 28 tooth plates instead of 32 like those of other hurdiid genera. [4] Each of the 4 large plate have 2 additional nodes, and the mouth opening has no additional inner plates. [2]
The trunk region have 17 segments with paired lateroventral flaps, as well as 4 caudal filiform blades on the tail. The setal blades (band of gill lamellae) were suggested to be positioned ventrally on each of the trunk segment, [2] contrary to the general reconstruction of radiodont with dorsal setal blades. [7]
Stanleycaris was most likely a visual predator that specialized primarily on macroscopic, soft-bodied benthic prey. Based on its streamlined body shape and broad trunk flaps, it may have been able to chase relatively fast-moving prey. [2] With strong differentiation of lateral–medial, inner–outer, and proximal–distal morphologies, Stanleycaris was probably able to trap (by using endites), manipulate (by using distal raptorial portion), and masticate (by using gnathites) prey items. [4]
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Phylogenetic position of Stanleycaris after Moysiuk & Caron 2022. [2] |
Stanleycaris was analysed to be one of the basalmost hurdiid radiodont, alongside Peytoia and Schinderhannes which shares some anatomical similarities. [8] [4] [9] [2] This suggests that the anomalocaridid/amplectobeluid-like traits (e.g. streamlined body; small head sclerites; frontal appendages with curved dorsal spines) found in these hurdiids represent radiodont ancestral characters. [8] [4] [2]
The specimen KUMIP 153923 from the Cambrian Wheeler Formation (Utah, United States), which was described by Robison (1985) as a whole body of new lobopodian species Aysheaia prolata, was reinterpreted as an isolated frontal appendage of Stanleycaris sp. by Pates, Daley & Ortega-Hernández (2017). [10]
Aysheaia is an extinct genus of soft-bodied lobopodian, known from the Middle 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.
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 previously, radiodonts were known only from exceptionally well-preserved fossil beds (Lagerstätten) from the Cambrian, 100 million years earlier.
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.
Caryosyntrips ("nutcracker") is an extinct genus of stem-arthropod which known from Canada, United States and Spain during the middle Cambrian.
Mureropodia is an animal that existed in what is now the Valdemiedes Formation of Spain during the early Cambrian period. It was described by José Antonio Gámez Vintaned, Eladio Liñán and Andrey Yu. Zhuravlev in 2011, and the type and only species is M. apae.
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.
Ursulinacaris is a genus of hurdiid radiodont from the Cambrian of North America. It contains one known species, Ursulinacaris grallae. It was described in 2019, based on fossils of the frontal appendages discovered in the 1990s and thereafter. The endites of Ursulinacaris were very slender, unlike other hurdiids such as Peytoia or Hurdia. It was initially reported as the first hurdiid with paired endites, but Moysiuk & Caron (2021) suggested that it is actually the preservation of the fossils and thus no paired endites.
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.
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 radiodont that lived in what is now northern China during the middle Cambrian period. This animal was described in 2020 based off 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 peytoiid 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.
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