The postabdomen was limbless and consisted of up to six segments and a terminal tail spine.
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The preabdomen is the broader segments of the anterior portion of the ophisthosoma while the postabdomen are the last five segments of the Eurypterus body. Each of the segments of the postabdomen contain lateral flattened protrusions known as the epimera with the exception of the last needle-like (styliform) segment known as the telson (the 'tail'). The segment immediately preceding the telson (which also has the largest epimera of the postabdomen) is known as the pretelson. An alternative way to divide the ophisthosoma is by function.
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Its postabdomen is moderately long and narrow, somewhat narrowing distally, its length being about 3.2 times its height. Its preanal angle is well defined, while its postanal angle is not so. The postanal margin of the postabdomen is provided with 8 to 9 groups of tiny denticles. It also counts with 12–14 lateral fascicles of long setules, which in distalmost fascicles the length of its setules exceed the width of the base of its postabdominal claw.
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Fossils and Strata, No. 4, pp. 255-270, Pl. 1 -3. The preabdomen, the front portion of the body, was narrow with axial furrows, while the postabdomen was narrow. The telson was a curved spine.
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When removed from the water, the animal often violently expels water from these siphons, hence the common name of "sea squirt". The body itself can be divided into up to three regions, although these are not clearly distinct in most species. The pharyngeal region contains the pharynx, while the abdomen contains most of the other bodily organs, and the postabdomen contains the heart and gonads. In many sea squirts, the postabdomen, or even the entire abdomen, are absent, with their respective organs being located more anteriorly.
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The species' head, antennule and labrum is the same as for the genus. The postabdomen narrows distally, the length of which is about 3.2 its height. Setules near the base of its postabdominal claws are short. Its antenna comprises less than 1/5 of its body length.
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The generic name is derived from "X," meaning "hunter" in Latin, and "US," meaning "extraordinary," thus referring to the animal's large raptorial appendages that were most probably used for seizing prey. The specific name, yus, is a kind of three-pronged spear, in reference to the triple-pointed postabdomen.
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The third and fourth walking legs were moderately sized, with short spines. The preabdomen, the front portion of the body, was narrow with axial furrows, while the postabdomen was narrow. The telson was a curved spine. 1955\. Merostomata. Treatise on Invertebrate Paleontology, Part P Arthropoda 2, Chelicerata, P34-P35.
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The euthycarcinoid body was divided into a cephalon (head), preabdomen, and postabdomen. The cephalon consisted of two segments and included mandibles, antennae and presumed eyes. The preabdomen consisted of five to fourteen tergites, each having up to three somites. Each somite had in turn a pair of uniramous, segmented legs.
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The metasoma, meanwhile, do not possess Blatfüsse. Some authors incorrectly use mesosoma and preabdomen interchangeably, as with metasoma and postabdomen. The main respiratory organs of Eurypterus were what seems to be book gills, located in branchial chambers within the segments of the mesosoma. They may have been used for underwater respiration.
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The ocellus is small, the eye being two times larger than the former. It possesses three major head pores of similar size with a narrow connection between them. The animal's thorax is three times longer than its abdomen. The postabdomen narrows distally, the length of which is equal to about 2.5 heights.
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Unlike most other synziphosurines with opisthosoma subdivided into a wide preabdomen and narrow postabdomen, the 10-segmented opisthosoma of Pseudoniscus possess undivided, metameric segmentation similar to Pasternakevia. Within Pseudoniscus, P. roosevelti is one of the few synziphosurines that confirmed to have lateral compound eyes, while the remain species lacking unambiguous evidence of it.
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Size comparison of L. dolichoschelus Lanarkopterus was a small to moderately large (ranging in size from less than 10 centimeters to over 30 centimeters) mixopterid eurypterid that like its close relative Mixopterus appeared almost scorpion- like with a broad and trilobed preabdomen, a narrow and tapering postabdomen and a sharped and curved telsonic spine.
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Sidneyia and Emeraldella). The clade was formally named Vicissicaudata in 2013, united by a differentiated terminal trunk area (postabdomen) that bears a pair of non-leg-like appendages. Numerous phylogenetic analysis also retrieved Vicissicaudata within Artiopoda, a diverse arthropod taxon comprise of trilobites and similar fossil taxa that may or may not closely related to chelicerates.
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Forfarella had a nearly rectangular head, with unknown eyes but which could be represented by a tubercle in the fossil. Its abdomen consisted of an almost trapezoidal preabdomen and a long, tapering postabdomen. The telson ("tail") is not preserved, but it was probably short. The appendages, known only from a few fragments, probably had swimming paddles that Forfarella used to swim actively.
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A cluster of short setules is located near the base of the postabdominal claws. The latter is long, almost straight, longer than the anal portion of the postabdomen. The spine at the end of the pecten is short. The antennule is long and narrow, with a length equating to about 4 widths, including 3 transverse rows of short setules at its anterior face.
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The segments were wide. A rapid contraction was observed in the postabdomen (segments 8 to 12) reminiscent of the scorpion abdomen, which seems to indicate a nepionic (immature) condition. Similar contraction is present in other immature eurypterids as well. The only known adult eurypterids to possess it are Carcinosoma scorpioides and several species of Eusarcana, in which the tail was heavily specialized.
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The second pair of walking legs was enormously developed, with long paired spines. The fourth pair of walking legs was nearly spineless. The preabdomen, the front portion of the body, was narrow with axial furrows, while the postabdomen was moderately narrow with broad, flat and curved appendages on the last body segment. The telson was short and lanceolate. 1955\. Merostomata.
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The second pair of walking legs is enormously developed, with long paired spines. The fourth pair of walking legs are nearly spineless. The preabdomen, the front portion of the body, is narrow with axial furrows, while the postabdomen is moderately narrow with broad, flat and curved appendages on the last body segment. The telson is short and lanceolate. 1955\. Merostomata.
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The length of the segments gradually increased towards the telson ("tail"). The opisthosoma (abdomen) of O. augusti is known in more detail; the preabdomen was a little wider than long, with raised areas representing branchial (of the gills) chambers or respiratory tissue of the branchial tract. The postabdomen was short, and its segments gradually narrowed towards the telson. Each of the postabdominal segments had small epimera.
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The three genera included in the Mycteroptidae, Mycterops, Woodwardopterus and Megarachne might represent different ontogenetic stages of each other based on the sizes of the referred specimens and the patterns of mucronation. This would sink the genera Woodwardopterus and Megarachne into Mycterops. Mycterops whitei is a fragmentary species that might not be referrable to the genus at all if more complete specimens show that it has a caudal postabdomen.
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Aplidium californicum is a compound tunicate forming sheets, mounds or slabs on rocks and other hard substrates. The tunic is jelly-like in consistency, 1 to 3 cm thick and a shiny yellow, orange, reddish-brown or a translucent white colour. The individual zooids are brown or buff, 6 mm long and arranged in oval or elongate systems. Each one is subdivided into a thorax, an abdomen and a postabdomen.
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The coxae of Appendage VI are broad and flat, resembling an 'ear'. The ophisthosoma (the abdomen) is composed of 12 segments, each consisting of a fused upper plate (tergite) and bottom plate (sternite). It is further subdivided in two ways. Based on the width and structure of each segment, they can be divided into the broad preabdomen (segments 1 to 7) and the narrow postabdomen (segments 8 to 12).
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The preabdomen (frontal part of 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.
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The prosoma of Camanchia covered by a smoothly curved subtriangular carapace with broad doublure (ventral thickening run through the margin of carapace). Detail of the 6 prosomal appendage pairs (chelicerae+5 leg pairs) obscure, at least the first leg pair (appendage II) have spur-like terminations. Opisthosoma is externally 10-segmented with tergites possses blunt pleurae (lateral extension). The last 3 opisthosomal segments forming a narrow postabdomen with short pleurae.
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Anderella is also one of the few synziphosurine genera with fossil showing evidence of appendages, but the details are obscure due to their poor preservation. The prosoma of Anderella possess a suboval carapace slightly longer than the externally 10-segmented opisthosoma (excluding telson). A row of axial nodes run through the opisthosomal tergites. The last 3 opisthosomal segments (which forming the postabdomen) are longer and lacking pleurae (lateral extensions).
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Bunodes is characterized by a vaulted carapace with radiated hump-like ridges. Within the 10-segmented opisthosoma, the first opisthosomal tergite is greatly reduced and always covered by the posterior region of preceding carapace, while the second tergite is significantly well- developed. the last 3 opisthosomal segments specialized into a narrow postabdomen and lacking tergopleurae (lateral extension of tergites). Tubercles of various sizes covering most of the dorsal surface of both carapace and tergites.
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The preabdomen had lateral convex margins and was quite short and broad, with the first tergite (dorsal half of the segment) being less wide than the subsequent ones. The postabdomen was narrow, had a constant width and did not have epimera (lateral "extensions" of the segment), like the preabdomen. The segments of the whole body were hardly distinguishable from each other. The integument of the body lacked ornamentation and was very smooth.
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The surface of the carapace was granulose (with granules) and had an ornamentation which consisted of minute rounded tubercles, some isolated and others confluent in sets of two or three. It was strengthened by prominent calcareous (with calcium) deposits. As in the rest of eurypterids, the opisthosoma (abdomen) had twelve segments. It was divided into the preabdomen (segments 1 to 6), which was telescoped (with segments overlapping each other) and postabdomen (segments 7 to 12).
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Its prosoma (head) was subquadrate (almost square) to parabolic (nearly U-shaped), with (bean-shaped) to subovate (nearly oval) eyes and surrounded by a marginal rim. The abdomen was composed by a fused buckler and a postabdomen that occupied most of the body length. The appendages (limbs) were uniform. The sixth and last pair of them had a paddle-like shape and was placed in front of the midpoint of the prosoma.
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In the postabdomen, segments 11 to 13 were somewhat longer than the previous ones. Each tergite carried an articular surface (joint) on its front, interpreted to represent arthrodial membranes (plane joints), which were a smooth and flattened facet, with a slight posterior ridge. These joints are identical to those of the eurypterids and arachnids, and are considered homologous. The telson ("tail") was small and semicircular, measuring 0.09 cm (0.036 in) in length.
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It counts with setae natatoriae about 2.1–2.3 the length of the preanal portion of its postabdomen. Its antennule is long and narrow, nearly reaching the tip of the rostrum; the antennular seta is thin, of about half the length of the antennule. It exhibits nine terminal aesthetascs, the two longest being about 2/3 the length of the antennule itself. All the aesthetascs project beyond the anterior margin of the head shield.
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Diploaspis casteri, a similar species of chasmataspidid Forfarella is classified as part of the family Diploaspididae, one of the two families in the order Chasmataspidida. It includes one single species, F. mitchelli, from the Early Devonian of Scotland. At the time Forfarella was described, members of Diploaspididae were defined as small chasmataspidids with a subrectangular or semicircular carapace, a tapering postabdomen and a short telson. Excluding the last one, which is uncertain, Forfarella coincided with these features.
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Alongside Pseudoniscus roosevelti, Legrandella lombardii is one of the few synziphosurine species that confirmed to have lateral compound eyes. The eyes are slit-like, located just below the opthalmic ridges on each side of the carapace. The opisthosoma is externally 11-segmented, subdivided into a 8-segmented preabdomen and 3-segmented postabdomen. Tergite of the 1st preabdomimal segment is a reduced microtergite while the remaining 7 tergite posses axial nodes and spine-like tergopleurae (lateral extension).
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The heart is a curved muscular tube lying in the postabdomen, or close to the stomach. Each end opens into a single vessel, one running to the endostyle, and the other to the dorsal surface of the pharynx. The vessels are connected by a series of sinuses, through which the blood flows. Additional sinuses run from that on the dorsal surface, supplying blood to the visceral organs, and smaller vessels commonly run from both sides into the tunic.
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They featured spine-like immovable spurs on their anterior margins. On the posterior margin of the seventh podomere was the movable spine-like podomere 7a, characteristic of the eurypterines. All the podomeres had similar proportions, except the distal spine which was slightly curved and probably had a pointed tip. The opisthosoma (abdomen) suffered a strong to moderate first order differentiation, that is, it was divided into a preabdomen (body segments 1 to 7) and a postabdomen (segments 8 to 12).
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The opisthosoma of Willwerathia most likely compose of 10 segments, each expressed by a tergite that bore a median dorsal spine and a pair of tergopleurae (lateral extensions). The opisthosoma subdivided into a wider, most likely 7-segmented preabdomen and a narrower, 3-segmented postabdomen. tergite of the first opisthosomal segment is reduced in length while the remaining segments posses well-developed tergites with lateral nodes and posteriorly curved tergopleurae. The final segment terminated with a short, teardrop-shaped telson.
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It is a poorly-known genus whose carapace (dorsal plate of the prosoma, head) was semiovate bordered by a marginal rim, with eyes laterally placed, a preabdomen and postabdomen (the two halves of the abdomen) with six segments each and a short spike-like telson ("tail"). It reached a total length of 7.5 centimetres (2.9 inches). These characteristics place Tylopterella in the family Onychopterellidae together with Onychopterella and Alkenopterus. Tylopterella is notable for its thick ornamentation and general body surface.
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Vague impressions distinguish the second, third and fourth tergites (dorsal half of the segments), but not the first one. The postabdomen (segments 5 to 13) also tapered posteriorly and was longer, with its 9 tergites distinguishable in the fossil and with a length of approximately each. The telson ("tail") is unknown, but it was probably short as in other contemporary chasmataspidids. The specimen had two cracks all over the prosoma (the head) and preabdomen, as well as dark patches probably corresponding to the ornamentation.
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A tunicate group from East Timor Almost all ascidians are hermaphrodites and conspicuous mature ascidians are sessile. The gonads are located in the abdomen or postabdomen, and include one testis and one ovary, each of which opens via a duct into the cloaca. Broadly speaking, the ascidians can be divided into species which exist as independent animals (the solitary ascidians) and those which are interdependent (the colonial ascidians). Different species of ascidians can have markedly different reproductive strategies, with colonial forms having mixed modes of reproduction.
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Copulation begins when the male positions his postabdomen over the ovipositor of the female, who raises the tip of her abdomen in response. If the female does not immediately respond to the male mounting her, he vibrates one or both of his legs next to the female's head. Copulation itself is brief, lasting approximately 24.10± 5.18 seconds, and is preceded by little or no pre- copulatory courtship. Males have been observed following females post- copulation as the female oviposits, sometimes mating between each bout of oviposition.
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The preserved elements include a thin, short postabdomen (¼ metasoma), granulation of the carapace (¼ dorsal shield of the Prosoma), ornament on the posterior tergite margins resembling hatching, and a weak and delicate pedipalpal claw (supposedly superimposed from beneath the body). A median gut trace and a feature representing either a Runzelung (wrinkle) or a stigma (¼ spiracle) on the margin of at least the fifth Mesosomal segment was described, but its presence is controversial.Dunlop, J. A., Kamenz, C., & Scholtz, G. (2007). Reinterpreting the morphology of the Jurassic scorpion Liassoscorpionides.
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However, the opisthosoma is most likely 11-segmented in origin, with the first segment being highly reduced (a synapomorphy of euchelicerates) and possibly covered by the preceding carapace. The last 3 segments form a narrow postabdomen and lacking lateral nodes. Fossil with preserved appendages Compared to other synziphosurines with only scarce or no discovery of any evidence of appendages, the appendages of Weinbergina are exceptionally well-preserved in many described fossil materials. Underneath the carapace are small chelicerae and pairs of well-developed, 8-segmented walking legs.
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Many colonial sea squirts are also capable of asexual reproduction, although the means of doing so are highly variable between different families. In the simplest forms, the members of the colony are linked only by rootlike projections from their undersides known as stolons. Buds containing food storage cells can develop within the stolons and, when sufficiently separated from the 'parent', may grow into a new adult individual. In other species, the postabdomen can elongate and break up into a string of separate buds, which can eventually form a new colony.
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In O. kokomoensis, the preabdomen (body segments 1 to 6) was as long as it was wide, while the postabdomen (segments 7 to 12) was short and compact and gradually increased in length posteriorly. It was the only species with considerably large epimera (lateral "extensions" of the segment) in the pretelson (segment that preceded the tail). In O. pumilus, the preabdomen was wider than long, the fourth segment being the widest. The postabodmen was longer, decreasing in width more rapidly in the eighth and ninth segments than in the rest.
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It differed from the rest of the species by the lack of large epimera in the pretelson, wider body proportions, the short length of the postabdomen and telson, the lanceolate form of the latter, the two projections of the eighth podomere and in a distal spine longer than in the rest of the species. The paratype, GSSA C427, is the largest known specimen. O. augusti was also compared to the enigmatic Silurian eurypterid Marsupipterus sculpturatus, concluding that the differences between the telson (the only known part of Marsupipterus) of both species are probably preservational.
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Wiedopterus was a eurypterid of medium size, the holotype and only known specimen preserving somewhere around half the animal and measuring about 40 mm in length, that can be differentiated from other eurypterids by several distinct features. These features include its trapezoid carapace with a narrow marginal rim, lateral eyes in a position close to the center of the carapace, a rounded and wide preabdomen with reduced tergites anteriorly, the tergites possessing narrow anterior articulation facets, a marked constriction between the preabdomen and the postabdomen and that the dorsal preabdomen lacks any prominent ornaments.
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It is typically divided into a preabdomen and postabdomen, although this is only clearly visible in scorpions, and in some orders, such as the Acari, the abdominal sections are completely fused. A telson is present in scorpions, where it has been modified to a stinger, and in the Schizomida, whip scorpions and Palpigradi.The Colonisation of Land: Origins and Adaptations of Terrestrial Animals Like all arthropods, arachnids have an exoskeleton, and they also have an internal structure of cartilage-like tissue, called the endosternite, to which certain muscle groups are attached. The endosternite is even calcified in some Opiliones.
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Carapace of Eysyslopterus patteni, the basalmost adelophthalmid genus and species. All adelophthalmids have a series of shared characteristics that make them different from the rest of eurypterids. However, some genera developed different features within Adelophthalmidae that divide the family into several smaller clades and groupings. The genera Parahughmilleria and Adelophthalmus form a derived clade based on the presence of enlarged spines on at least one podomere in the appendage V (fifth limb), the presence of epimera in the postabdomen (body segments 8 to 12) and the large spatulae that has been associated with the genital operculum.
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Chasmataspidids, sometime referred to as chasmataspids, are a group of extinct chelicerate arthropods that form the order Chasmataspidida. Chasmataspidids are probably related to horseshoe crabs (Xiphosura) and/or sea scorpions (Eurypterida), with more recent studies suggest that they form a clade (Dekatriata) with Eurypterida and Arachnida. Chasmataspidids are known sporadically in the fossil record through to the mid-Devonian, with possible evidence suggest that they also present during the late Cambrian. Chasmataspidids are most easily recognised by having an abdomen divided into a short forepart (preabdomen) and a longer hindpart (postabdomen) each comprising 4 and 9 segments respectively.
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The petiole is formed by the first two segments of the abdomen, the first of which has a slight bulge on the tergite. In the male the postabdomen is highly characteristic, the sternite of the 5th postabdominal segment is shallow divided into 2 lobes, each of which bears two or three stout bristles at the tip; the entire structure is very similar to that of "Electrobata" tertiaria. The 6th sternite is triradiate like in Metopochetus, but like in Eurybatini not compressed laterally and with a trough-like channel in the middle. The subepandrial sclerite of male Badisis has a very small prominence with a minute setula at its tip.
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Two specimens of O. kokomoensis from the Kokomo waterlime, seen from above It is thought that the genus Onychopterella lived in brackish (water with salt but not completely salty) and possibly marine water. It was undoubtedly nektobenthic, that is, being able to swim but staying most of the time in the stratum. The less developed and narrow swimming legs, as well as the short and stout postabdomen, show that the genus was not a very good nor active swimmer, possibly using its terminal spine to walk. The broad doublure (the fringe of the dorsal exoskeleton) of the carapace could have been adapted for shoveling or digging.
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As in the rest of the chasmataspidids, its opisthosoma (abdomen) was composed of a preabdomen (segments 1 to 4) and a postabdomen (segments 5 to 13), in Dvulikiaspis with very slight first order differentiation (that is, both parts little separated from each other). The segments in general were wide rectangles with almost straight boundaries, narrowing slightly posteriorly. The microtergite (the short first tergite, dorsal half of the segment) was conformed to the posterior margin of the prosoma. The second to fourth segments were merged into a weakly expressed "buckler", which was wide rectangular with rounded lateral edges and narrow- angled shoulders (anterolateral "extensions" of the buckler).
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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 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 the opisthosoma was covered in structures evolved from modified opisthosomal appendages.
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Regarding other chasmataspidids, Forfarella was considerably similar to Diploaspis casteri, although it had a longer postabdomen, perhaps because of a taphonomic distortion (that is, a defect product of the fossilization of the organism) of the specimen. The genus also resembled other Devonian chasmataspidids, but differed from the Ordovician Chasmataspis, which was much larger and had genal spines (spines protruding from the posterolateral corners of the carapace). What differentiated Forfarella from the rest of the chasmataspidids was the dimensions of its body, its size, the shape of its carapace and the distinctive subtrapezoidal preabdomen. Forfarella is a poorly preserved genus only known from one single specimen, and it has not been included to date in any phylogenetic analysis or cladogram.
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Lamsdell already commented the possibility that D. menneri could represent a chasmataspidid in 2011. This was demonstrated in 2014, when it was redescribed as a new genus of chasmataspidid and removed from Eurypterida, noting its distinction with other diploaspidids and suggesting a relationship with Loganamaraspis. In 2019, during the description of the new Ordovician chasmataspidid Hoplitaspis hiawathai, it was suggested that Dvulikiaspis, Hoplitaspis and Loganamaraspis could represent a new family separated from Diploaspididae. These genera share the proportionality of the body (the postabdomen comprises the majority of the body length), a poorly differentiated buckler and a paddle projecting in front of the midpoint of the prosoma, although this is not certain in Loganamaraspis.
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In 1912, American paleontologists John Mason Clarke & Rudolf Ruedemann declared that the differences between Eusarcus and all related forms of eurypterids were so great that it was "entirely evident" that Eusarcus was distinct from other eurypterids. They referred the Scottish Wenlock-age Eurypterus species E. obesus (described by English geologist Henry Woodward in 1868) to the genus, alongside the Pridoli-Lochkovian-age Czech species E. acrocephalus (described by Austrian paleontologist Max Semper in 1898) on the grounds of both possessing triangular carapaces similar to E. scorpionis as well as an abruptly narrowing postabdomen. Furthermore, Clarke and Ruedemann concluded that Eusarcus was sufficiently similar to the related Carcinosoma to be designated as synonymous with it. As Eusarcus had been named earlier than Carcinosoma, the taxonomical laws of priority dictated that Eusarcus would be the name of the taxon.
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Two new specimens, PIN 5116/1 (a nearly complete opisthosoma) and PIN 5116/3 (a poorly preserved dorsal fossil), were found in 1974 on an expedition by Yu. N. Mokrousov, but they were not described. They were found in the Upper Zub Formation-Lower Kureika Formation, in the Krasnoyarsk Krai. In 2011, the British geologist and paleobiologist James C. Lamsdell noted that by the presence of a paddle-like sixth appendage, three-segmented fused buckler and nine-segmented postabdomen, T. menneri could in fact represent a chasmataspidid, questioning the position of T. menneri in Tylopterella and Eurypterida. In 2014, the paleontologists David J. Marshall, Lamsdell, Evgeniy S. Shpinev and Simon J. Braddy recognized T. menneri as a new separate genus of chasmataspidid due to its body size and position of the prosomal appendages, specially the sixth appendage in the anterior half of the prosoma.
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1912 reconstruction of E. scorpionis. Eusarcana can be differentiated from other eurypterids by the considerably narrow border between the prosoma (head) and opisthosoma (abdomen), which is particularly thin considering the subsequent broad and large ellipse-shape of the abdomen. The postabdomen (or tail) also narrows rather quickly from the preceding segments. Further features distinctive of the genus include that the carapace (segment covering the head) is clearly triangular in shape, with eyes placed on the rim of it and positioned forwards, the fact that all walking legs possess spines and that they decrease in length the further back they were placed as well as the cylindrically shaped and sharp telson (tail spike).Clarke, J. K., Ruedemann R. (1912) "The Eurypterida of New York" In comparison with many other eurypterids, Eusarcana was a rather large animal, with the largest species (also the type species) E. scorpionis reaching lengths of 80 cm (31.5 in).
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