121-489: Carcinosoma (meaning "crab body") is a genus of eurypterid , an extinct group of aquatic arthropods . Fossils of Carcinosoma are restricted to deposits of late Silurian (Late Llandovery to Early Pridoli ) age. Classified as part of the family Carcinosomatidae , which the genus lends its name to, Carcinosoma contains seven species from North America and Great Britain . Carcinosomatid eurypterids had unusual proportions and features compared to other eurypterids, with
242-564: A cosmopolitan distribution . Though the eurypterids continued to be abundant and diversify during the Early Devonian (for instance leading to the evolution of the pterygotid Jaekelopterus , the largest of all arthropods), the group was one of many heavily affected by the Late Devonian extinction . The extinction event, only known to affect marine life (particularly trilobites, brachiopods and reef -building organisms) effectively crippled
363-509: A cuticle composed of proteins and chitin . As in other chelicerates , the body was divided into two tagmata (sections); the frontal prosoma (head) and posterior opisthosoma (abdomen). The prosoma was covered by a carapace (sometimes called the "prosomal shield") on which both compound eyes and the ocelli (simple eye-like sensory organs) were located. The prosoma also bore six pairs of appendages which are usually referred to as appendage pairs I to VI. The first pair of appendages,
484-408: A lung , plastron or a pseudotrachea . Plastrons are organs that some arthropods evolved secondarily to breathe air underwater. This is considered an unlikely explanation since eurypterids had evolved in water from the start and they would not have organs evolved from air-breathing organs present. In addition, plastrons are generally exposed on outer parts of the body while the eurypterid gill tract
605-452: A broad abdomen, thin and long tail and spined and forward-facing walking appendages. They were not as streamlined as other groups but had considerably more robust and well developed walking appendages. In Carcinosoma , these spined walking appendages are thought to have been used to create a trap to capture prey in. The telson (the posteriormost division of the body) of Carcinosoma appears to have possessed distinct segmentation, Carcinosoma
726-579: A close resemblance of the swimming legs, C. punctatum is assumed to have been similar in appearance to C. newlini . C. punctatum can be distinguished from C. newlini by the serration along the margin of the distal podomeres of C. punctatum being more pronounced. C. harleyi , from the Late Ludlow epoch, was described mainly based on specimens previously known (some having been reported by Salter as early as 1859) but previously referred to Eurypterus punctatus . Recognized by Kjellesvig-Waering as distinct,
847-454: A dual respiratory system was present, which would have allowed for short periods of time in terrestrial environments. The name Eurypterida comes from the Ancient Greek words εὐρύς ( eurús ), meaning 'broad' or 'wide', and πτερόν ( pterón ), meaning 'wing', referring to the pair of wide swimming appendages present in many members of the group. The eurypterid order includes
968-726: A gait like that of most modern insects. The weight of its long abdomen would have been balanced by two heavy and specialized frontal appendages, and the center of gravity might have been adjustable by raising and positioning the tail. Preserved fossilized eurypterid trackways tend to be large and heteropodous and often have an associated telson drag mark along the mid-line (as with the Scottish Hibbertopterus track). Such trackways have been discovered on every continent except for South America. In some places where eurypterid fossil remains are otherwise rare, such as in South Africa and
1089-458: A genus of modern beetles and is today considered synonymous with the genus Brachygnathus . Claypole replaced the name Eurysoma with the new name Carcinosoma . Carcinosoma means "crab body" deriving from Latin cancer , "crab", and soma , "body". In 1868, English geologist and paleontologist Henry Woodward named a new species of Eurypterus , E. scorpioides , based on fossils from Lanarkshire , Scotland. Woodward could easily distinguish
1210-416: A manner similar to modern horseshoe crabs, by grabbing and shredding food with their appendages before pushing it into their mouth using their chelicerae. Fossils preserving digestive tracts have been reported from fossils of various eurypterids, among them Carcinosoma , Acutiramus and Eurypterus . Though a potential anal opening has been reported from the telson of a specimen of Buffalopterus , it
1331-425: A meter (1.64 ft) even if the extended chelicerae are not included. Two other eurypterids have also been estimated to have reached lengths of 2.5 metres; Erettopterus grandis (closely related to Jaekelopterus ) and Hibbertopterus wittebergensis , but E. grandis is very fragmentary and the H. wittenbergensis size estimate is based on trackway evidence, not fossil remains. The family of Jaekelopterus ,
SECTION 10
#17331046423881452-530: A new species C. harleyi based on fossils from the Ludlow epoch of the Welsh Borderland . Kjellesvig-Waering could differentiate C. harleyi from C. punctatum based on C. harleyi lacking serrations on the eighth podomere of the swimming leg and the serrations of the ninth podomere being less developed. C. punctatum was diagnosed by Kjellesvig-Waering in 1961 based on the considerably pronounced serrations of
1573-471: A rowing type of propulsion similar to that of crabs and water beetles . Larger individuals may have been capable of underwater flying (or subaqueous flight ) in which the motion and shape of the paddles are enough to generate lift , similar to the swimming of sea turtles and sea lions . This type of movement has a relatively slower acceleration rate than the rowing type, especially since adults have proportionally smaller paddles than juveniles. However, since
1694-407: A small portion of the structure is not preserved, making more segments possible), otherwise not definitely reported from a eurypterid. The only other eurypterid from which a segmented structure occurring as part of the telson has been reported in is the slimonid Salteropterus abbreviatus . With such segmentation reported from two separate eurypterid genera, it is possible that the eurypterid telson
1815-547: Is a genital appendage. This appendage, an elongated rod with an internal duct, is found in two distinct morphs, generally referred to as "type A" and "type B". These genital appendages are often preserved prominently in fossils and have been the subject of various interpretations of eurypterid reproduction and sexual dimorphism. Type A appendages are generally longer than those of type B. In some genera they are divided into different numbers of sections, such as in Eurypterus where
1936-495: Is a lightweight build. Factors such as locomotion, energy costs in molting and respiration, as well as the actual physical properties of the exoskeleton , limit the size that arthropods can reach. A lightweight construction significantly decreases the influence of these factors. Pterygotids were particularly lightweight, with most fossilized large body segments preserving as thin and unmineralized. Lightweight adaptations are present in other giant paleozoic arthropods as well, such as
2057-399: Is actually developed from a formerly normal abdominal segment and is thus not homologous to the telson of other arthropod groups. Further studies of Salteropterus has since revealed that the perceived "segmentation" of its "post-telson" was misinterpreted ornamentation of an elongated and unusually shaped telson and not actual segmentation, making the segmentation of Carcinosoma unique. As
2178-956: Is adapted from a larger cladogram (simplified to only display the Carcinosomatoidea) in a 2007 study by eurypterid researcher O. Erik Tetlie, in turn based on results from various phylogenetic analyses on eurypterids conducted between 2004 and 2007. The second cladogram below is simplified from a study by Lamsdell et al. (2015). Tetlie (2007) Carcinosoma newlini Eusarcana scorpionis Rhinocarcinosoma vaningeni Carcinosoma scoticus Carcinosoma scorpiodes Mixopterus multispinosus Mixopterus simonsoni Mixopterus kiaeri Lamsdell et al. (2015) Megalograptidae Mixopteridae Holmipterus suecicus Rhinocarcinosoma vaningeni Carcinosoma newlini Carcinosoma libertyi Eusarcana acrocephalus Eusarcana scorpionis The walking legs of Carcinosoma were turned forward, which also directed
2299-523: Is also possible and the structure may represent the unfused tips of the appendages. Located between the dorsal and ventral surfaces of the Blattfüsse associated with the type A appendages is a set of organs traditionally described as either "tubular organs" or "horn organs". These organs are most often interpreted as spermathecae (organs for storing sperm ), though this function is yet to be proven conclusively. In arthropods, spermathecae are used to store
2420-483: Is located behind the Blattfüssen . Instead, among arthropod respiratory organs, the eurypterid gill tracts most closely resemble the pseudotracheae found in modern isopods . These organs, called pseudotracheae, because of some resemblance to the tracheae (windpipes) of air-breathing organisms, are lung-like and present within the pleopods (back legs) of isopods. The structure of the pseudotracheae has been compared to
2541-487: Is made up of the first six exoskeleton segments fused together into a larger structure. The seventh segment (thus the first opisthosomal segment) is referred to as the metastoma and the eighth segment (distinctly plate-like) is called the operculum and contains the genital aperature. The underside of this segment is occupied by the genital operculum, a structure originally evolved from ancestral seventh and eighth pair of appendages. In its center, as in modern horseshoe crabs,
SECTION 20
#17331046423882662-517: Is more likely that the anus was opened through the thin cuticle between the last segment before the telson and the telson itself, as in modern horseshoe crabs. Eurypterid coprolites discovered in deposits of Ordovician age in Ohio containing fragments of a trilobite and eurypterid Megalograptus ohioensis in association with full specimens of the same eurypterid species have been suggested to represent evidence of cannibalism . Similar coprolites referred to
2783-537: Is much more of a marine influence in many of the sections yielding Adelophthalmus than has previously been acknowledged." Similarly, a study of the eurypterid Hibbertopterus from the Carboniferous of New Mexico concluded that the habitat of some eurypterids "may need to be re-evaluated". The sole surviving eurypterine family, Adelophthalmidae, was represented by only a single genus, Adelophthalmus . The hibbertopterids, mycteroptids and Adelophthalmus survived into
2904-625: Is possible that many eurypterid species thought to be distinct actually represent juvenile specimens of other species, with paleontologists rarely considering the influence of ontogeny when describing new species. Studies on a well-preserved fossil assemblage of eurypterids from the Pragian -aged Beartooth Butte Formation in Cottonwood Canyon , Wyoming , composed of multiple specimens of various developmental stages of eurypterids Jaekelopterus and Strobilopterus , revealed that eurypterid ontogeny
3025-439: Is the first record of land locomotion by a eurypterid. The trackway provides evidence that some eurypterids could survive in terrestrial environments, at least for short periods of time, and reveals information about the stylonurine gait. In Hibbertopterus , as in most eurypterids, the pairs of appendages are different in size (referred to as a heteropodous limb condition). These differently sized pairs would have moved in phase, and
3146-795: Is the metastoma becoming proportionally less wide. This ontogenetic change has been observed in members of several superfamilies, such as the Eurypteroidea, the Pterygotioidea and the Moselopteroidea . No fossil gut contents from eurypterids are known, so direct evidence of their diet is lacking. The eurypterid biology is particularly suggestive of a carnivorous lifestyle. Not only were many large (in general, most predators tend to be larger than their prey), but they had stereoscopic vision (the ability to perceive depth). The legs of many eurypterids were covered in thin spines, used both for locomotion and
3267-465: Is the only known eurypterid to possess this feature. At 2.2 meters (7.2 ft) in length, the species C. punctatum is the largest carcinosomatoid eurypterid by far and is among the largest eurypterids overall, rivalling the large pterygotid eurypterids (such as Jaekelopterus ) in size. Other species of the genus were considerably smaller, with most ranging from 70 centimeters (2.3 ft) to 100 centimeters (3.3 ft) in length. Carcinosoma
3388-418: Is unlikely the "gill tract" contained functional gills when comparing the organ to gills in other invertebrates and even fish. Previous interpretations often identified the eurypterid "gills" as homologous with those of other groups (hence the terminology), with gas exchange occurring within the spongy tract and a pattern of branchio-cardiac and dendritic veins (as in related groups) carrying oxygenated blood into
3509-661: The Early Ordovician or Late Cambrian period. With approximately 250 species, the Eurypterida is the most diverse Paleozoic chelicerate order. Following their appearance during the Ordovician, eurypterids became major components of marine faunas during the Silurian , from which the majority of eurypterid species have been described. The Silurian genus Eurypterus accounts for more than 90% of all known eurypterid specimens. Though
3630-619: The Eurypteridae . When genera such as Erieopterus or Eurypterus occur in great numbers other genera and families are more rare, though groups such as dolichopterids , carcinosomatids and pterygotids tend to occur in small numbers. The environments with such faunas appear to be quieter waters such as lagoons , estuaries and bays . The third and final recognized type of fauna is one dominated by hughmilleriids and stylonurids , generally alongside sandy bottoms and with few other associated fossils. The environments inhabited by this third fauna
3751-521: The Stylonuroidea , Kokomopteroidea and Mycteropoidea as well as eurypterine groups such as the Pterygotioidea, Eurypteroidea and Waeringopteroidea . The most successful eurypterid by far was the Middle to Late Silurian Eurypterus , a generalist , equally likely to have engaged in predation or scavenging . Thought to have hunted mainly small and soft-bodied invertebrates, such as worms , species of
Carcinosoma - Misplaced Pages Continue
3872-457: The Wenlock epoch of Scotland at 38 centimeters (1.25 ft) in length. Carcinosoma was first described under the name Eurysoma (meaning "wide body", deriving from Greek εὐρύς, "wide", and Latin soma , "body") by British American geologist and paleobotanist Edward Waller Claypole in 1890, who named the type species of the new genus E. newlini in honor of a C. E. Newlin who had collected
3993-530: The coxae (limb segments) used for feeding. These appendages were generally walking legs that were cylindrical in shape and were covered in spines in some species. In most lineages, the limbs tended to get larger the farther back they were. In the Eurypterina suborder , the larger of the two eurypterid suborders, the sixth pair of appendages was also modified into a swimming paddle to aid in traversing aquatic environments. The opisthosoma comprised 12 segments and
4114-513: The distal parts of its swimming leg, but the diagnosis is only valid for the lectotype specimen of the species, BGS GSM89435 (compromising the distal parts of a swimming leg discovered in deposits of Middle Ludlow age in the Mocktree Shale of Leintwardine in Herefordshire, England), and four other specimens from the same locality (BMNH 39389, BMNH In. 43804, BGS GSM89561 and GSM89568). Due to
4235-409: The opisthosoma of Carcinosoma wasn't as streamlined as that of more active eurypterids and on account of its unique telson morphology, it is believed that Carcinosoma was not a very active swimmer. It is unlikely to have been well adapted to a completely nektonic (actively swimming) lifestyle and is more likely to have been nektobenthic (swimming near the bottom). The flat metasoma of Carcinosoma
4356-442: The rhizodonts , were the new apex predators in marine environments. However, various recent findings raise doubts about this, and suggest that these eurypterids were euryhaline forms that lived in marginal marine environments, such as estuaries, deltas, lagoons, and coastal ponds. One argument is paleobiogeographical; pterygotoid distribution seems to require oceanic dispersal. A recent review of Adelophthalmoidea admitted that "There
4477-405: The spermatophore received from males. This would imply that the type A appendage is the female morph and the type B appendage is the male. Further evidence for the type A appendages representing the female morph of genital appendages comes in their more complex construction (a general trend for female arthropod genitalia). It is possible that the greater length of the type A appendage means that it
4598-656: The telson , the posteriormost division of the body, which in most species took the form of a blade-like shape. In some lineages, notably the Pterygotioidea , the Hibbertopteridae and the Mycteroptidae , the telson was flattened and may have been used as a rudder while swimming. Some genera within the superfamily Carcinosomatoidea , notably Eusarcana , had a telson similar to that of modern scorpions and may have been capable of using it to inject venom . The coxae of
4719-527: The Devonian, large two meter (6.5+ ft) pterygotids such as Acutiramus were already present during the Late Silurian. Their ecology ranged from generalized predatory behavior to ambush predation and some, such as Pterygotus itself, were active apex predators in Late Silurian marine ecosystems. The pterygotids were also evidently capable of crossing oceans, becoming one of only two eurypterid groups to achieve
4840-577: The Late Ludlow epoch of England at 100 centimeters (3.3 ft), C. newlini from the Early Pridoli epoch of the United States at 90 centimeters (3.0 ft), C. scoticus from the Llandovery epoch of Scotland at 75 centimeters (2.46 ft) and C. spiniferum from the Late Ludlow epoch of the United States at 70 centimeters (2.3 ft). The second smallest known species was C. scorpioides from
4961-804: The Middle Ordovician suggests that eurypterids either originated during the Early Ordovician and experienced a rapid and explosive radiation and diversification soon after the first forms evolved, or that the group originated much earlier, perhaps during the Cambrian period. As such, the exact eurypterid time of origin remains unknown. Though fossils referred to as "primitive eurypterids" have occasionally been described from deposits of Cambrian or even Precambrian age, they are not recognized as eurypterids, and sometimes not even as related forms, today. Some animals previously seen as primitive eurypterids, such as
Carcinosoma - Misplaced Pages Continue
5082-590: The Middle Ordovician, 467.3 million years ago . There are also reports of even earlier fossil eurypterids in the Fezouata Biota of Late Tremadocian (Early Ordovician) age in Morocco , but these have yet to be thoroughly studied, and are likely to be peytoiid appendages. Pentecopterus was a relatively derived eurypterid, part of the megalograptid family within the carcinosomatoid superfamily. Its derived position suggests that most eurypterid clades, at least within
5203-641: The Middle Silurian and the Early Devonian, with an absolute peak in diversity during the Pridoli epoch , 423 to 419.2 million years ago, of the very latest Silurian. This peak in diversity has been recognized since the early twentieth century; of the approximately 150 species of eurypterids known in 1916, more than half were from the Silurian and a third were from the Late Silurian alone. Though stylonurine eurypterids generally remained rare and low in number, as had been
5324-549: The Pterygotidae, is noted for several unusually large species. Both Acutiramus , whose largest member A. bohemicus measured 2.1 meters (6.9 ft), and Pterygotus , whose largest species P. grandidentatus measured 1.75 meters (5.7 ft), were gigantic. Several different contributing factors to the large size of the pterygotids have been suggested, including courtship behaviour, predation and competition over environmental resources. Giant eurypterids were not limited to
5445-586: The Stylonurina, this appendage takes the form of a long and slender walking leg, while in the Eurypterina, the leg is modified and broadened into a swimming paddle. Other than the swimming paddle, the legs of many eurypterines were far too small to do much more than allow them to crawl across the sea floor . In contrast, a number of stylonurines had elongated and powerful legs that might have allowed them to walk on land (similar to modern crabs ). A fossil trackway
5566-538: The abundance and diversity previously seen within the eurypterids. A major decline in diversity had already begun during the Early Devonian and eurypterids were rare in marine environments by the Late Devonian. During the Frasnian stage four families went extinct, and the later Famennian saw an additional five families going extinct. As marine groups were the most affected, the eurypterids were primarily impacted within
5687-530: The ancient continent of Laurentia , and demersal (living on the seafloor ) and basal animals from the continents Avalonia and Gondwana. The Laurentian predators, classified in the family Megalograptidae (comprising the genera Echinognathus , Megalograptus and Pentecopterus ), are likely to represent the first truly successful eurypterid group, experiencing a small radiation during the Late Ordovician. Eurypterids were most diverse and abundant between
5808-442: The animal in question could possibly have measured just short of 2 meters (6.6 ft) in length. More robust than the pterygotids, this giant Hibbertopterus would possibly have rivalled the largest pterygotids in weight, if not surpassed them, and as such be among the heaviest arthropods. The two eurypterid suborders, Eurypterina and Stylonurina , are distinguished primarily by the morphology of their final pair of appendages. In
5929-454: The appendage via tracts, but these supposed tracts remain unpreserved in available fossil material. Type B appendages, assumed male, would have produced, stored and perhaps shaped spermatophore in a heart-shaped structure on the dorsal surface of the appendage. A broad genital opening would have allowed large amounts of spermatophore to be released at once. The long furca associated with type B appendages, perhaps capable of being lowered like
6050-476: The body) was broad and ovally shaped whilst the postabdomen (the posterior part of the body) was narrow and cylindrical. The prosoma (head) was subtriangular in shape with the small compound eyes placed at the front. The metasoma of Carcinosoma was covered in fine and elongated scales and was quite flat, a feature which separates the genus from Eusarcana where the metasoma was almost cylindrical. A well-preserved specimen of C. newlini , specimen number 502 in
6171-414: The body. The primary analogy used in previous studies has been horseshoe crabs, though their gill structure and that of eurypterids are remarkably different. In horseshoe crabs, the gills are more complex and composed of many lamellae (plates) which give a larger surface area used for gas exchange. In addition, the gill tract of eurypterids is proportionally much too small to support them if it is analogous to
SECTION 50
#17331046423886292-458: The case during the preceding Ordovician, eurypterine eurypterids experienced a rapid rise in diversity and number. In most Silurian fossil beds, eurypterine eurypterids account for 90% of all eurypterids present. Though some were likely already present by the Late Ordovician (simply missing from the fossil record so far), a vast majority of eurypterid groups are first recorded in strata of Silurian age. These include both stylonurine groups such as
6413-420: The coastlines and shallow inland seas of Euramerica. During the Late Silurian the pterygotid eurypterids, large and specialized forms with several new adaptations, such as large and flattened telsons capable of being used as rudders, and large and specialized chelicerae with enlarged pincers for handling (and potentially in some cases killing) prey appeared. Though the largest members of the family appeared in
6534-564: The collections of the American Museum of Natural History (collected in the Kokomo Formation of Indiana ), preserves the integument in enough detail to determine the coloration C. newlini would have possessed in life. By surveying the distribution of fossilized pigment cells and comparing them with those of modern scorpions , scientists were able to see the pattern and specific colors C. newlini would have possessed in life. Overall,
6655-401: The color was similar to that of modern scorpions and to that of another eurypterid which had been similarly studied, Megalograptus ohioensis . The dorsal side of the prosoma, mesosoma and the tergites (segments) of the metasoma were light brown while elongated scales alongside the exoskeleton were darker brown grading into black at the apex of the scales. Smaller scales alongside the edges of
6776-695: The cuticle) after which they underwent rapid and immediate growth. Some arthropods, such as insects and many crustaceans, undergo extreme changes over the course of maturing. Chelicerates, including eurypterids, are in general considered to be direct developers, undergoing no extreme changes after hatching (though extra body segments and extra limbs may be gained over the course of ontogeny in some lineages, such as xiphosurans and sea spiders ). Whether eurypterids were true direct developers (with hatchlings more or less being identical to adults) or hemianamorphic direct developers (with extra segments and limbs potentially being added during ontogeny) has been controversial in
6897-409: The eurypterine suborder, had already been established at this point during the Middle Ordovician. The earliest known stylonurine eurypterid, Brachyopterus , is also Middle Ordovician in age. The presence of members of both suborders indicates that primitive stem-eurypterids would have preceded them, though these are so far unknown in the fossil record. The presence of several eurypterid clades during
7018-411: The eurypterine suborder. Only one group of stylonurines (the family Parastylonuridae ) went extinct in the Early Devonian. Only two families of eurypterines survived into the Late Devonian at all ( Adelophthalmidae and Waeringopteridae). The eurypterines experienced their most major declines in the Early Devonian, during which over 50% of their diversity was lost in just 10 million years. Stylonurines, on
7139-508: The eurypterine swimming paddles varied from group to group. In the Eurypteroidea , the paddles were similar in shape to oars. The condition of the joints in their appendages ensured their paddles could only be moved in near-horizontal planes, not upwards or downwards. Some other groups, such as the Pterygotioidea, would not have possessed this condition and were probably able to swim faster. Most eurypterines are generally agreed to have utilized
7260-451: The existence of the previous name. In 2012, American paleontologists Jason A. Dunlop and James Lamsdell designated Paracarcinosoma as a junior synonym of Eusarcana per the taxonomic laws of priority. Carcinosoma is classified as part of the family Carcinosomatidae, a family within the superfamily Carcinosomatoidea, alongside the genera Eusarcana , Eocarcinosoma , Rhinocarcinosoma and possibly Holmipterus . The cladogram below
7381-454: The family Pterygotidae. An isolated 12.7 centimeters (5.0 in) long fossil metastoma of the carcinosomatoid eurypterid Carcinosoma punctatum indicates the animal would have reached a length of 2.2 meters (7.2 ft) in life, rivalling the pterygotids in size. Another giant was Pentecopterus decorahensis , a primitive carcinosomatoid, which is estimated to have reached lengths of 1.7 meters (5.6 ft). Typical of large eurypterids
SECTION 60
#17331046423887502-579: The fossil deposits of the Welsh Borderland, examples of Carcinosoma occur together with representatives of the pterygotid genera Erettopterus and Pterygotus over a period of millions of years (though other eurypterids, such as Salteropterus , Dolichopterus , Hughmilleria , Eurypterus , Marsupipterus , Mixopterus , Parahughmilleria , Slimonia , Tarsopterella and Stylonurus are also present in lesser numbers). Other types of late Silurian eurypterid faunas include one dominated by
7623-564: The fossils. The Eurysoma specimens had been discovered in deposits of Early Pridoli age in the Kokomo Formation of Indiana alongside several other eurypterid specimens, all of which at the time were referred to Eurypterus lacustris (though Claypole noted in the same paper that this may have been done hastily). Later in the same year, Claypole discovered that the name Eurysoma was preoccupied and thus not available to be used for his genus of eurypterids. Eurysoma had been named in 1831 for
7744-476: The found tracks each being about 7.6 centimeters (3.0 in) in diameter. Other eurypterid ichnogenera include Merostomichnites (though it is likely that many specimens actually represent trackways of crustaceans) and Arcuites (which preserves grooves made by the swimming appendages). In eurypterids, the respiratory organs were located on the ventral body wall (the underside of the opisthosoma). Blattfüsse , evolved from opisthosomal appendages, covered
7865-568: The gathering of food. In some groups, these spiny appendages became heavily specialized. In some eurypterids in the Carcinosomatoidea, forward-facing appendages were large and possessed enormously elongated spines (as in Mixopterus and Megalograptus ). In derived members of the Pterygotioidea, the appendages were completely without spines, but had specialized claws instead. Other eurypterids, lacking these specialized appendages, likely fed in
7986-651: The genus Strabops from the Cambrian of Missouri , are now classified as aglaspidids or strabopids . The aglaspidids, once seen as primitive chelicerates, are now seen as a group more closely related to trilobites. The fossil record of Ordovician eurypterids is quite poor. The majority of eurypterids once reportedly known from the Ordovician have since proven to be misidentifications or pseudofossils . Today only 11 species can be confidently identified as representing Ordovician eurypterids. These taxa fall into two distinct ecological categories; large and active predators from
8107-513: The genus (of which the most common is the type species, E. remipes ) account for more than 90% (perhaps as many as 95%) of all known fossil eurypterid specimens. Despite their vast number, Eurypterus are only known from a relatively short temporal range, first appearing during the Late Llandovery epoch (around 432 million years ago) and being extinct by the end of the Pridoli epoch. Eurypterus
8228-512: The genus are, which makes the assignment of the other species to Carcinosoma less secure. Kjellesvig-Waering and Caster also recognized Eusarcus and Carcinosoma to be distinct genera when revising the superfamily Carcinosomatoidea, and coined the replacement name Paracarcinosoma to designate the species previously assigned to Eusarcus . E. scorpionis was designated the type species . Caster and Kjellesvig-Waering made no mention of Embrik Strand or Eusarcana , and they were likely not aware of
8349-413: The genus on account of their similarities with C. newlini and species previously referred to Eusarcus . In 1934, 59 years after it had been described, Eusarcus was recognized as a name preoccupied by a harvestman . The Norwegian geologist Leif Størmer proposed that the name of the taxon should be next oldest available and valid name for the genus, Carcinosoma . During the preparation for his paper on
8470-429: The giant millipede Arthropleura , and are possibly vital for the evolution of giant size in arthropods. In addition to the lightweight giant eurypterids, some deep-bodied forms in the family Hibbertopteridae were also very large. A carapace from the Carboniferous of Scotland referred to the species Hibbertoperus scouleri measures 65 cm (26 in) wide. As Hibbertopterus was very wide compared to its length,
8591-412: The gills of other groups. To be functional gills, they would have to have been highly efficient and would have required a highly efficient circulatory system. It is considered unlikely, however, that these factors would be enough to explain the large discrepancy between gill tract size and body size. It has been suggested instead that the "gill tract" was an organ for breathing air, perhaps actually being
8712-587: The group continued to diversify during the subsequent Devonian period, the eurypterids were heavily affected by the Late Devonian extinction event . They declined in numbers and diversity until becoming extinct during the Permian–Triassic extinction event (or sometime shortly before) 251.9 million years ago. Although popularly called "sea scorpions", only the earliest eurypterids were marine ; many later forms lived in brackish or fresh water , and they were not true scorpions . Some studies suggest that
8833-432: The group lived primarily in the waters around and within the ancient supercontinent of Euramerica . Only a handful of eurypterid groups spread beyond the confines of Euramerica and a few genera, such as Adelophthalmus and Pterygotus , achieved a cosmopolitan distribution with fossils being found worldwide. Like all other arthropods , eurypterids possessed segmented bodies and jointed appendages (limbs) covered in
8954-406: The highly streamlined pterygotid eurypterids. In contrast, the walking legs of the carcinosomatids were in general more robust and better developed. Indeed, the walking legs (the second to fifth pair of appendages) were stout and strong and increased in size anteriorly , from the fifth to third pair of appendages, though the first pair of appendages were much shorter than the following pairs. As such,
9075-580: The invaginations leading to asphyxiation . Furthermore, most eurypterids would have been aquatic their entire lives. No matter how much time was spent on land, organs for respiration in underwater environments must have been present. True gills, expected to have been located within the branchial chamber within the Blattfüssen , remain unknown in eurypterids. Like all arthropods, eurypterids matured and grew through static developmental stages referred to as instars . These instars were punctuated by periods during which eurypterids went through ecdysis (molting of
9196-406: The issue, Størmer also discussed the situation with fellow Norwegian researcher Embrik Strand , who helped confirm that Carcinosoma was not preoccupied. Strand would subsequently propose the replacement name Eusarcana in 1942, despite the problem having been dealt with by Størmer, who he had been in contact with, eight years earlier. The reasons for proposing the name during the circumstances of
9317-409: The joints of C. harleyi makes the species very distinct from C. punctatum and other species of Carcinosoma . In 1964, both C. punctatum and C. harleyi were still recognized as part of Carcinosoma following an emended diagnosis of the genus by Kjellesvig-Waering and American paleontologist Kenneth Edward Caster, though C. harleyi was only tentatively recognized. Further species recognized at
9438-439: The large spines on the appendages forward. In C. newlini , these flat and forward-facing legs are thought to have been used to create a trap to capture prey in. The strong structures seen in C. newlini are not reflected in other carcinosomatids. For instance, the appendages of Eusarcana were much more weakly developed and would not have served as an effective weapon. Eusarcana is more likely to have relied on its telson, taking
9559-491: The larger sizes of adults mean a higher drag coefficient , using this type of propulsion is more energy-efficient. Some eurypterines, such as Mixopterus (as inferred from attributed fossil trackways), were not necessarily good swimmers. It likely kept mostly to the bottom, using its swimming paddles for occasional bursts of movements vertically, with the fourth and fifth pairs of appendages positioned backwards to produce minor movement forwards. While walking, it probably used
9680-495: The largest known arthropod ever to have lived, is Jaekelopterus rhenaniae . A chelicera from the Emsian Klerf Formation of Willwerath, Germany measured 36.4 centimeters (14.3 in) in length, but is missing a quarter of its length, suggesting that the full chelicera would have been 45.5 centimeters (17.9 in) long. If the proportions between body length and chelicerae match those of its closest relatives, where
9801-516: The largest known arthropods ever to have lived. The largest, Jaekelopterus , reached 2.5 meters (8.2 ft) in length. Eurypterids were not uniformly large and most species were less than 20 centimeters (8 in) long; the smallest eurypterid, Alkenopterus , was only 2.03 centimeters (0.80 in) long. Eurypterid fossils have been recovered from every continent. A majority of fossils are from fossil sites in North America and Europe because
9922-604: The largest of all known carcinosomatoid eurypterids and it rivals the largest pterygotid eurypterids, such as the 2.5-meter (8.2 ft) long Jaekelopterus , in size. Other species of Carcinosoma were smaller, most being in the range of 70 centimeters (2.3 ft) to 100 centimeters (3.3 ft) in length. Perhaps the most recognizable features of Carcinosoma are its spined appendages and its broad and flattened mesosoma (the first six segments of its abdomen). Carcinosomatid eurypterids such as Carcinosoma had less streamlined bodies than those of some other groups, notably
10043-497: The last ever radiation within the eurypterids, which gave rise to several new forms capable of "sweep-feeding" (raking through the substrate in search of prey). Only three eurypterid families—Adelophthalmidae, Hibbertopteridae and Mycteroptidae—survived the extinction event in its entirety. It was assumed that these were all freshwater animals, which would have rendered the eurypterids extinct in marine environments, and with marine eurypterid predators gone, sarcopterygians , such as
10164-400: The metasomal tergites were also brown but contrasted against the lighter brown of the other integument. The operculum (the first and second abdominal segments) and the plates of the abdomen were brown but lighter than the tergites and their scales were, as with the other scales, darker than the surrounding integument. Black-tipped scales also occurred on the legs, where the general integument
10285-501: The only pair placed before the mouth, is called the chelicerae ( homologous to the fangs of spiders). They were equipped with small pincers used to manipulate food fragments and push them into the mouth. In one lineage, the Pterygotidae , the chelicerae were large and long, with strong, well-developed teeth on specialised chelae (claws). The subsequent pairs of appendages, numbers II to VI, possessed gnathobases (or "tooth-plates") on
10406-808: The opisthosoma was covered in structures evolved from modified opisthosomal appendages. Throughout the opisthosoma, these structures formed plate-like structures termed Blattfüsse ( lit. ' leaf-feet ' in German). These created a branchial chamber (gill tract) between preceding Blattfüsse and the ventral surface of the opisthosoma itself, which contained the respiratory organs. The second to sixth opisthosomal segments also contained oval or triangular organs that have been interpreted as organs that aid in respiration. These organs, termed Kiemenplatten or "gill tracts", would potentially have aided eurypterids to breathe air above water, while Blattfüssen , similar to organs in modern horseshoe crabs , would cover
10527-424: The other hand, persisted through the period with more or less consistent diversity and abundance but were affected during the Late Devonian, when many of the older groups were replaced by new forms in the families Mycteroptidae and Hibbertopteridae. It is possible that the catastrophic extinction patterns seen in the eurypterine suborder were related to the emergence of more derived fish. Eurypterine decline began at
10648-548: The parts that serve for underwater respiration . The appendages of opisthosomal segments 1 and 2 (the seventh and eighth segments overall) were fused into a structure termed the genital operculum, occupying most of the underside of the opisthosomal segment 2. Near the anterior margin of this structure, the genital appendage (also called the Zipfel or the median abdominal appendage) protruded. This appendage, often preserved very prominently, has consistently been interpreted as part of
10769-433: The past. Hemianamorphic direct development has been observed in many arthropod groups, such as trilobites , megacheirans , basal crustaceans and basal myriapods . True direct development has on occasion been referred to as a trait unique to arachnids . There have been few studies on eurypterid ontogeny as there is a general lack of specimens in the fossil record that can confidently be stated to represent juveniles. It
10890-581: The period. These faunas were typically dominated by one or more particular eurypterid families, the dominant groups depending on the environment and location. Three such types of eurypterid faunas have been documented from the late Silurian, out of which a Carcinosomatidae-Pterygotidae fauna is the most marine type. All known examples of Carcinosoma are known from marine beds, typically occurring with trilobites , starfish , bryozoans , brachiopods , linguloids and other marine animals. Carcinosoma also prominently occurs together with pterygotid eurypterids. In
11011-434: The point when jawless fish first became more developed and coincides with the emergence of placoderms (armored fish) in both North America and Europe. Stylonurines of the surviving hibbertopterid and mycteroptid families completely avoided competition with fish by evolving towards a new and distinct ecological niche. These families experienced a radiation and diversification through the Late Devonian and Early Carboniferous,
11132-511: The preceding and adjacent brown segment. Carcinosoma ranged in size from 20 centimeters (7.9 in) to 2.2 meters (7.2 ft) in length, with the largest species by far being C. punctatum , known from the Ludlow epoch of England , and the smallest being C. libertyi , known from the Late Llandovery epoch of Canada . Though no other species came close to the size of C. punctatum , many species were moderately large, including C. harleyi from
11253-452: The ratio between claw size and body length is relatively consistent, the specimen of Jaekelopterus that possessed the chelicera in question would have measured between 233 and 259 centimeters (7.64 and 8.50 ft), an average 2.5 meters (8.2 ft), in length. With the chelicerae extended, another meter (3.28 ft) would be added to this length. This estimate exceeds the maximum body size of all other known giant arthropods by almost half
11374-445: The reproduction and sexual dimorphism of eurypterids is difficult, as they are only known from fossilized shells and carapaces. In some cases, there might not be enough apparent differences to separate the sexes based on morphology alone. Sometimes two sexes of the same species have been interpreted as two different species, as was the case with two species of Drepanopterus ( D. bembycoides and D. lobatus ). The eurypterid prosoma
11495-458: The reproductive system and occurs in two recognized types, assumed to correspond to male and female. Eurypterids were highly variable in size, depending on factors such as lifestyle, living environment and taxonomic affinity . Sizes around 100 centimeters (3.3 ft) are common in most eurypterid groups. The smallest eurypterid, Alkenopterus burglahrensis , measured just 2.03 centimeters (0.80 in) in length. The largest eurypterid, and
11616-435: The rest of the former supercontinent Gondwana , the discoveries of trackways both predate and outnumber eurypterid body fossils. Eurypterid trackways have been referred to several ichnogenera, most notably Palmichnium (defined as a series of four tracks often with an associated drag mark in the mid-line), wherein the holotype of the ichnospecies P. kosinkiorum preserves the largest eurypterid footprints known to date with
11737-405: The same genera. The primary function of the long, assumed female, type A appendages was likely to take up spermatophore from the substrate into the reproductive tract rather than to serve as an ovipositor, as arthropod ovipositors are generally longer than eurypterid type A appendages. By rotating the sides of the operculum, it would have been possible to lower the appendage from the body. Due to
11858-551: The second pair of walking legs were the longest. Each walking appendage possessed long and curved spines, often two such spines occurring per joint. These spines are one of the defining features of the carcinosomatid family, along with that the swimming legs have slightly elongated and expanded seventh and eighth podomeres (leg segments). The body of Carcinosoma was somewhat oddly proportioned in comparison to other eurypterids, though similar to that of related carcinosomatids (particularly Eusarcana ). The preabdomen (frontal part of
11979-434: The shape of a sharp and curved stinger similar to that of scorpions and potentially capable of injecting venom. Instead of taking the shape of a scorpion-like stinger, the telson of Carcinosoma was slightly flattened and expanded anteriorly. The telsons of most eurypterids ends in a spike but the telson of Carcinosoma ended in a small and expanded structure with distinct segmentation, fossils preserving ten segments (though
12100-413: The short stride length indicates that Hibbertopterus crawled with an exceptionally slow speed, at least on land. The large telson was dragged along the ground and left a large central groove behind the animal. Slopes in the tracks at random intervals suggest that the motion was jerky. The gait of smaller stylonurines, such as Parastylonurus , was probably faster and more precise. The functionality of
12221-429: The sixth pair of appendages were overlaid by a plate that is referred to as the metastoma, originally derived from a complete exoskeleton segment. The opisthosoma itself can be divided either into a " mesosoma " (comprising segments 1 to 6) and " metasoma " (comprising segments 7 to 12) or into a "preabdomen" (generally comprising segments 1 to 7) and "postabdomen" (generally comprising segments 8 to 12). The underside of
12342-441: The species Lanarkopterus dolichoschelus from the Ordovician of Ohio contain fragments of jawless fish and fragments of smaller specimens of Lanarkopterus itself. Though apex predatory roles would have been limited to the very largest eurypterids, smaller eurypterids were likely formidable predators in their own right just like their larger relatives. As in many other entirely extinct groups, understanding and researching
12463-454: The species from other genera present at the locality, such as Slimonia and Pterygotus . Another species of Eurypterus , E. scoticus was named in 1899 by Scottish zoologist and paleontologist Malcolm Laurie based on fragmentary remains recovered in deposits of Llandovery age in Scotland. In 1912, American paleontologists John Mason Clarke and Rudolf Ruedemann noted that Carcinosoma
12584-519: The species is named in honor of John Harley, one of the earliest collectors of eurypterid fossils in the region. Noted as moderately large in size by Kjellesvig-Waering, the holotype specimen of C. harleyi (No. 89434 in the collection of the Geological Survey and Museum in London) is a fragment of a swimming leg measuring 5 centimeters (2.0 in) in length. The nearly complete lack of serrations in
12705-427: The spongy structure of the eurypterid gill tracts. It is possible the two organs functioned in the same way. Some researchers have suggested that eurypterids may have been adapted to an amphibious lifestyle, using the full gill tract structure as gills and the invaginations within it as pseudotrachea. This mode of life may not have been physiologically possible, however, since water pressure would have forced water into
12826-492: The structure. Though the Kiemenplatte is referred to as a "gill tract", it may not necessarily have functioned as actual gills. In other animals, gills are used for oxygen uptake from water and are outgrowths of the body wall. Despite eurypterids clearly being primarily aquatic animals that almost certainly evolved underwater (some eurypterids, such as the pterygotids, would even have been physically unable to walk on land), it
12947-622: The time remains unknown, but critique from contemporary researchers of Strand for his studies in systematics and an apparent desire to name as many taxa as possible may explain the situation somewhat. As it was seen as completely unnecessary at the time, Strand's Eusarcana was overlooked and not even mentioned in subsequent eurypterid studies. In 1961, American paleontologist Erik N. Kjellesvig-Waering classified Eurypterus punctatus (originally described as Pterygotus punctatus by English paleontologist and prominent eurypterid researcher John William Salter in 1859) as Carcinosoma punctatum and named
13068-423: The time were C. libertyi and C. logani (both from Ontario, Canada; C. logani was later found to be a crustacean and not a eurypterid at all), C. spiniferum (from New York, United States), C. newlini (from Indiana, United States), C. scorpioides and C. scoticus (both from Scotland). Out of these species, only C. newlini and C. scorpioides preserve the swimming legs, where the diagnostic characters of
13189-464: The type A appendage is divided into three but the type B appendage into only two. Such division of the genital appendage is common in eurypterids, but the number is not universal; for instance, the appendages of both types in the family Pterygotidae are undivided. The type A appendage is also armed with two curved spines called furca (lit. 'fork' in Latin). The presence of furca in the type B appendage
13310-519: The type A appendage, could have been used to detect whether a substrate was suitable for spermatophore deposition. Until 1882 no eurypterids were known from before the Silurian. Contemporary discoveries since the 1880s have expanded the knowledge of early eurypterids from the Ordovician period. The earliest eurypterids known today, the megalograptid Pentecopterus , date from the Darriwilian stage of
13431-400: The underside and created a gill chamber where the "gill tracts" were located. Depending on the species, the eurypterid gill tract was either triangular or oval in shape and was possibly raised into a cushion-like state. The surface of this gill tract bore several spinules (small spines), which resulted in an enlarged surface area. It was composed of spongy tissue due to many invaginations in
13552-429: The way different plates overlay at its location, the appendage would have been impossible to move without muscular contractions moving around the operculum. It would have been kept in place when not it use. The furca on the type A appendages may have aided in breaking open the spermatophore to release the free sperm inside for uptake. The "horn organs," possibly spermathecae, are thought to have been connected directly to
13673-400: Was also restricted to the continent Euramerica (composed of the equatorial continents Avalonia, Baltica and Laurentia), which had been completely colonized by the genus during its merging and was unable to cross the vast expanses of ocean separating this continent from other parts of the world, such as the southern supercontinent Gondwana. As such, Eurypterus was limited geographically to
13794-492: Was among the largest eurypterids , with isolated fossil remains consisting of a 12.7 centimeters (5.0 in) long metastoma (a plate overlaying the coxae of the first six appendages) of the species C. punctatum indicating a full length of 2.2 meters (7.2 ft). Fossil prosomal appendages (appendages attached to the head) referred to the species could possibly increase this estimate to an overall length of around 2.5 meters (8.2 ft). This massive size makes C. punctatum
13915-420: Was dark brown. The spines of the walking legs were dark brown but black at their tips. The flattened scales on the swimming paddles also graded into black, though the paddle was otherwise brown. The coxae were light brown, with darker scales. The gnathobases ("tooth-plates" on the coxae used when feeding) were completely black, as were the telson (the posteriormost division of the body) whose color contrasted with
14036-497: Was discovered in Carboniferous-aged fossil deposits of Scotland in 2005. It was attributed to the stylonurine eurypterid Hibbertopterus due to a matching size (the trackmaker was estimated to have been about 1.6 meters (5.2 ft) long) and inferred leg anatomy. It is the largest terrestrial trackway—measuring 6 meters (20 ft) long and averaging 95 centimeters (3.12 ft) in width—made by an arthropod found thus far. It
14157-436: Was likely less marine than the others, possibly representing the more brackish parts of bays and estuaries. Eurypterid Eurypterids , often informally called sea scorpions , are a group of extinct arthropods that form the order Eurypterida . The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago . The group is likely to have appeared first either during
14278-452: Was more or less parallel and similar to that of extinct and extant xiphosurans, with the largest exception being that eurypterids hatched with a full set of appendages and opisthosomal segments. Eurypterids were thus not hemianamorphic direct developers, but true direct developers like modern arachnids. The most frequently observed change occurring through ontogeny (except for some genera, such as Eurypterus , which appear to have been static)
14399-475: Was probably used as at least partially as aid when swimming, suggested by the pretelson being slightly expanded in comparison to other eurypterids. As a considerable majority of described eurypterid species are known from the Silurian, particularly the late Silurian, researchers have concluded that the group peaked in diversity and number during this time. Complex eurypterid faunas, compromising several different species in different ecological roles , are typical of
14520-447: Was sufficiently similar to the related eurypterid Eusarcus to be designated as synonymous with it. As Eusarcus had been named in 1875, fifteen years earlier than Carcinosoma , its name had priority and replaced Carcinosoma . At this time, the combined genus of Eusarcus contained several species that are today seen as Carcinosoma , including C. newlini , C. scoticus and C. scorpioides , which Clarke and Ruedemann had referred to
14641-518: Was used as an ovipositor (used to deposit eggs). The different types of genital appendages are not necessarily the only feature that distinguishes between the sexes of eurypterids. Depending on the genus and species in question, other features such as size, the amount of ornamentation and the proportional width of the body can be the result of sexual dimorphism. In general, eurypterids with type B appendages (males) appear to have been proportionally wider than eurypterids with type A appendages (females) of
#387612