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Examples of Limulus polyphemus with cephalothoracic injuries. (1) Four 'U' shaped embayments on right anterior cephalothorax (white arrows). (2-4) Small 'U' shaped embayment on left anterior cephalothorax. (2) Entire specimen. (3, 4) Close-ups of cephalothoracic buckling (white arrows). (5-7) Injury to left anterior cephalothorax (white arrows). (1, 4-5) images in dorsal view. (2, 5) Images in ventral view. (3, 7) Images in lateral view. No specimens were accessioned into collections.
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Xiphosurida comprise an archetypal arthropod group of considerable interest to both biological and palaeontological researchers. This appeal is generated by a combination of unique anatomical features, utility as modern analogues for extinct arthropod groups, and an impressive fossil record. Although xiphosurids have been extensively studied, there...
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... teratologies. The most often reported Lim- ulus polyphemus abnormalities are to the telson: 5% of males and 3% of females in the Delaware Bay spawning population have abnormal telsons (Botton and Loveland, 1989). Excluding short or missing telsons, two types of potential teratologies are described here: (1) forked telsons (the most often observed teratologies) and (2) double telsons (Table 1). These teratologies range between sym- metrically bifurcated telsons, as noted by Gudger (1935), to asymmetrical ( Table 1). The forked telson can also result in an overdeveloped axial spine ( Figure 1.4). Double telsons have full-length telson spines that bifurcate at the opisthosomal base (Gudger, 1935, Figure 1.1, 1.3). Other telson teratologies include the extension of the posterior opisthosoma parallel with a damaged telson (Figure 1.5) and tel- son spines that curve in side-on view (van der Meer Mohr, 1941). Cephalothoracic abnormalities. Injuries along the Limulus polyphemus cephalothoracic margin are rarer than telson teratologies. The cephalotho- racic injuries consist of at least one 'U' shaped embayment in the dorsal margin, with rare exam- ples of multiple embayments (Figure 2.1-7). One extreme cephalothoracic injury to the Tachypleus tridentatus specimen was noted (OUMNH.ZC.25121): a large 'U' shaped injury to the right cephalothorax producing a sharply buck- led border (Figure 3.1-5). This specimen is similar to the L. polyphemus specimen in Jell (1989, figure 1). However, the Jell (1989) specimen has buckling 6 that forced the cephalothoracic margin to extend out laterally from the original margin, a feature not noted here. Other cephalothoracic abnormalities include a slit-like embayment to the left posterior cephalothorax (van der Meer Mohr, 1944, figure 2) and a hole in the dorsal cephalothorax ( ). Opisthosomal injuries. Only one example of an opisthosomal injury was documented here: a 'V' shaped embayment on the left side of the Tachy- pleus tridentatus specimen (OUMNH.ZC.25121). A moveable spine has been removed and the two most posterior spines are shorter than those on the right side (Figure 3.1, 3.3-5). This injury is poten- tially similar to the opisthosomal injuries described, but not figured, in van der Meer Mohr (1941). The documented injury is more extreme than the Jell (1989, figure 1) specimen, as the Jell specimen did not have an embayment. The other previously doc- umented opisthosomal injuries are broken poste- rior opisthosomal process on female Limulus polyphemus (Table 1) from mating ( Brockmann, 1990;Shuster Jr, 2009). Appendage injuries. No examples of abnormal appendages were illustrated here. However, injured cephalothoracic and thoracetronic append- ages have been documented in previous studies (Table 1). Damaged pretarsus, apotele sections and processes of pushing legs are the most docu- mented appendage injuries (van der Meer Mohr, 1935, 1941. Damaged and amputated walking legs and the loss of male pedipalps have also been noted (Bursey, 1977;Schaller et al., , 2005Duffy et al., 2006). Such injuries can persist through multiple moulting events ( Itow et al., 1998a). Only one type of injured thoracetronic appendage is noted: injured book gills (Botton and Loveland, 1989). The examples noted here are detailed further in Table ...
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... walchi is superbly preserved in 3D in the Solnhofen Limestone (Jurassic) ( Barthel et al., 1990). Two injured specimens from this deposit are documented (MCZ 106500 and MCZ 106372). One specimen had a 'W' shaped embay- ment on the left anterior cephalothorax, extending slightly into the most-anterior opisthosoma ( Figure 4.1, 4.3). The injury is cicatrised (has raised relief) and is therefore distinct from the breaks in the fos- sil. The other specimen had an asymmetric 'V' shaped embayment on the left anterior cephalotho- rax (Figure 4.2, ...
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... sections of fossil xiphosurids are occasionally preserved well enough to examine for injuries, which augments the trace fossil evi- dence of predation noted in Diedrich (2011). The xiphosurids considered here have broadly similar cephalothoracic morphologies, and similar asym- metric 'V' and 'W' shaped injuries (Figures 4.1-4, 5.3-5). Furthermore, the only unusual non-marginal cephalothoracic features recorded here were on Euproops danae. The lineations along the cephalo- thorax suggest deformation immediately after a moulting event, perhaps from scratching. Alterna- tively, an equally plausible origin would be plastic deformation of a freshly moulted exoskeleton, where the lineations are subparallel folds due to compression. No examples of 'U' shaped injuries were identified on the extinct xiphosurid species, and we suggest that smaller 'U' shaped injuries, like those to Limulus polyphemus, may not be iden- tifiable (Figure 2). This is because during healing, injuries become less angular and prominent, and are therefore harder to distinguish from tapho- nomic ...
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... the Jell (1989) specimen has buckling 6 that forced the cephalothoracic margin to extend out laterally from the original margin, a feature not noted here. Other cephalothoracic abnormalities include a slit-like embayment to the left posterior cephalothorax (van der Meer Mohr, 1944, figure 2) and a hole in the dorsal cephalothorax ( ). Opisthosomal injuries. ...
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... injury is cicatrised (has raised relief) and is therefore distinct from the breaks in the fos- sil. The other specimen had an asymmetric 'V' shaped embayment on the left anterior cephalotho- rax (Figure 4.2, 4.4). ...
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... tively, an equally plausible origin would be plastic deformation of a freshly moulted exoskeleton, where the lineations are subparallel folds due to compression. No examples of 'U' shaped injuries were identified on the extinct xiphosurid species, and we suggest that smaller 'U' shaped injuries, like those to Limulus polyphemus, may not be iden- tifiable (Figure 2). This is because during healing, injuries become less angular and prominent, and are therefore harder to distinguish from tapho- nomic distortion. ...
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... teratologies. The most often reported Lim- ulus polyphemus abnormalities are to the telson: 5% of males and 3% of females in the Delaware Bay spawning population have abnormal telsons (Botton and Loveland, 1989). Excluding short or missing telsons, two types of potential teratologies are described here: (1) forked telsons (the most often observed teratologies) and (2) double telsons (Table 1). These teratologies range between sym- metrically bifurcated telsons, as noted by Gudger (1935), to asymmetrical ( Table 1). The forked telson can also result in an overdeveloped axial spine ( Figure 1.4). Double telsons have full-length telson spines that bifurcate at the opisthosomal base (Gudger, 1935, Figure 1.1, 1.3). Other telson teratologies include the extension of the posterior opisthosoma parallel with a damaged telson (Figure 1.5) and tel- son spines that curve in side-on view (van der Meer Mohr, 1941). Cephalothoracic abnormalities. Injuries along the Limulus polyphemus cephalothoracic margin are rarer than telson teratologies. The cephalotho- racic injuries consist of at least one 'U' shaped embayment in the dorsal margin, with rare exam- ples of multiple embayments (Figure 2.1-7). One extreme cephalothoracic injury to the Tachypleus tridentatus specimen was noted (OUMNH.ZC.25121): a large 'U' shaped injury to the right cephalothorax producing a sharply buck- led border (Figure 3.1-5). This specimen is similar to the L. polyphemus specimen in Jell (1989, figure 1). However, the Jell (1989) specimen has buckling 6 that forced the cephalothoracic margin to extend out laterally from the original margin, a feature not noted here. Other cephalothoracic abnormalities include a slit-like embayment to the left posterior cephalothorax (van der Meer Mohr, 1944, figure 2) and a hole in the dorsal cephalothorax ( ). Opisthosomal injuries. Only one example of an opisthosomal injury was documented here: a 'V' shaped embayment on the left side of the Tachy- pleus tridentatus specimen (OUMNH.ZC.25121). A moveable spine has been removed and the two most posterior spines are shorter than those on the right side (Figure 3.1, 3.3-5). This injury is poten- tially similar to the opisthosomal injuries described, but not figured, in van der Meer Mohr (1941). The documented injury is more extreme than the Jell (1989, figure 1) specimen, as the Jell specimen did not have an embayment. The other previously doc- umented opisthosomal injuries are broken poste- rior opisthosomal process on female Limulus polyphemus (Table 1) from mating ( Brockmann, 1990;Shuster Jr, 2009). Appendage injuries. No examples of abnormal appendages were illustrated here. However, injured cephalothoracic and thoracetronic append- ages have been documented in previous studies (Table 1). Damaged pretarsus, apotele sections and processes of pushing legs are the most docu- mented appendage injuries (van der Meer Mohr, 1935, 1941. Damaged and amputated walking legs and the loss of male pedipalps have also been noted (Bursey, 1977;Schaller et al., , 2005Duffy et al., 2006). Such injuries can persist through multiple moulting events ( Itow et al., 1998a). Only one type of injured thoracetronic appendage is noted: injured book gills (Botton and Loveland, 1989). The examples noted here are detailed further in Table ...
Context 8
... walchi is superbly preserved in 3D in the Solnhofen Limestone (Jurassic) ( Barthel et al., 1990). Two injured specimens from this deposit are documented (MCZ 106500 and MCZ 106372). One specimen had a 'W' shaped embay- ment on the left anterior cephalothorax, extending slightly into the most-anterior opisthosoma ( Figure 4.1, 4.3). The injury is cicatrised (has raised relief) and is therefore distinct from the breaks in the fos- sil. The other specimen had an asymmetric 'V' shaped embayment on the left anterior cephalotho- rax (Figure 4.2, ...
Context 9
... sections of fossil xiphosurids are occasionally preserved well enough to examine for injuries, which augments the trace fossil evi- dence of predation noted in Diedrich (2011). The xiphosurids considered here have broadly similar cephalothoracic morphologies, and similar asym- metric 'V' and 'W' shaped injuries (Figures 4.1-4, 5.3-5). Furthermore, the only unusual non-marginal cephalothoracic features recorded here were on Euproops danae. The lineations along the cephalo- thorax suggest deformation immediately after a moulting event, perhaps from scratching. Alterna- tively, an equally plausible origin would be plastic deformation of a freshly moulted exoskeleton, where the lineations are subparallel folds due to compression. No examples of 'U' shaped injuries were identified on the extinct xiphosurid species, and we suggest that smaller 'U' shaped injuries, like those to Limulus polyphemus, may not be iden- tifiable (Figure 2). This is because during healing, injuries become less angular and prominent, and are therefore harder to distinguish from tapho- nomic ...
Similar publications
Euarthropods have a tough exoskeleton that provides crucial protection from predation and parasitism. However, this is restrictive to growth and must be periodically moulted. The moulting sequence is well-known from extant arthropods, consisting of: (i) the long inter-moult stage, in which no changes occur to the hardened exoskeleton; (ii) the pre-...
Citations
... Cephalic injuries are rare in Cambrian trilobites, a record that contrasts evidence from younger Paleozoic deposits (see Resser & Howell, 1938;Alpert & Moore, 1975;Cowie & McNamara, 1978;Owen, 1985;Skinner, 2004;Fatka, Budil & Grigar, 2015;Bicknell & Paterson, 2018;Bicknell, Pates & Botton, 2018;Smith, Paterson & Brock, 2018). Due to this rarity, the Centrapleura phoenix specimen displaying a U-shaped injury in the cephalic region (Figs. ...
Biomineralised remains of trilobites provide important insight into the evolutionary history of a diverse, extinct group of arthropods. Their exoskeletons are also ideal for recording malformations, including evidence of post-injury repair. Re-examination of historic collections and the study of new specimens is important for enhancing knowledge on trilobite malformations across this diverse clade. To expand the records of these abnormalities and present explanations for their formation, we document eight malformed trilobite specimens, as well as one carcass, housed within the Commonwealth Palaeontological Collection at Geoscience Australia in Canberra. We present examples of Asthenopsis, Burminresia, Centropleura, Coronocephalus, Dolicholeptus, Galahetes, Papyriaspis, and Xystridura from Cambrian, Ordovician, and Silurian deposits of Australia. Most of the malformed specimens show W-, U-, or L-shaped indentations that reflect injuries from either failed predation or complications during moulting, and a mangled carcass is ascribed to either successful predation or post-mortem scavenging. We also uncover examples of teratologies, such as bifurcated pygidial ribs and pygidial asymmetry, in addition to evidence of abnormal recovery (i.e., fusion of thoracic segments) from a traumatic incident.
... The xiphosurids, true horseshoe crabs, have been extensively documented marine arthropods based on their stable morphology and the fossil record. The American horseshoe crab, Limulus polyphemus Linnaeus, 1758, is a well-studied extant xiphosurid and has been investigated since the 1800s [1] including the [2,3,4,5], ecological and biological aspect [6][7][8][9][10][11][12][13][14], biochemical also paleontological [15,16,17] studies. In recent years especially in Indonesia, research on horseshoe crab focused on biological and ecological studies for two data deficient species, Tachypleus gigas and Carcinoscorpius rorundicauda [18 -23] for conservation efforts and sustainable population. ...
... However, the injuries that occur with U-shaped final results are due to the molting process that occurs at each individual stage or instar. Injuries with a V and Y shape may indicate injuries resulting from tearing of the softer exoskeleton after molting, or injuries that have undergone substantial recovery, or both [5,27]. Here only one individual sample showed evidence of recovery (Fig. 2E), under these conditions it was suspected that there was damage to the appendages. ...
The xiphosurids are a typical chelicerae group with massive morphological, anatomical, biochemical, and ecological documentation. Despite this study, information about extant horseshoe crab abnormalities is underexplored, especially in the Indonesian region. Thus, this study aims to investigate the abnormal horseshoe crab in Subang, West Java. This research was conducted from January until February 2020 in Legon Wetan, Subang, West Java. Here, we only documented abnormalities of extant xiphosurids namely Tachypleus gigas . During the study, we greatly found extant abnormal xiphosurids by identifying 45 specimens with a wide range of abnormalities on the cephalothorax (prosoma), thoracetron (opisthosoma), telson, and appendages. The abnormal coastal horseshoe crab found also included adults (male and female) and juveniles ranging from 11.6 cm to 21 cm of carapace width. We note that the most common abnormal body parts are the cephalothorax and the thoracetron. Although the original cause may be unknown, the three main causes of the abnormality-inducing which are injuries such as self-injuries or fishing net injuries, physiologic developmental abnormalities or teratologies, and pathologies.
... However, one would expect a stunted genal spine (see Hessin 1988;Bicknell et al. 2023) as opposed to complete spine removal and localised rounding of the injury. Furthermore, this injury is comparable morphologically to other examples of W-shaped indentations to the cephalic region (see Resser & Howell 1938;Babcock 1993;Bicknell et al. 2018d;Bicknell et al. 2022a). As such, while we cannot completely discount moulting, it seems more likelythatthiscephalicinjuryreflectsfailedpredation. ...
Insight into how extinct animals responded to injuries developmental malfunctions and pathologies can be derived by examining malformed specimens. Trilobites are an ideal group for understanding how a completely extinct group of arthropods responded to and recovered from these conditions, as their biomineralised exoskeletons preserves malformations. Here we consider a slab containing eight individuals of the asaphid trilobite Pseudogygites latimarginatus from the Colling-wood Member of the Lindsay Formation, Canada. Examining this slab, two individuals with malfor-mations are documented. These malformations are considered injuries and used to demonstrate how P. latimarginatus recovered from failed predation attacks, allowing us to consider possible predator groups. The cluster is interpreted as possible evidence for an in situ biological aggregation that was preserved prior to a moulting event. Implications for this gregarious behaviour are considered, presenting more insight into the palaeoecology of Ordovician asaphid trilobites.
... RECORDS of predation within the fossil record present important information regarding predator-prey dynamics in palaeoecosystems (Brett 1990, Kowalewski 2002, Klompmaker et al. 2019. Injured specimens (Babcock 1993, Vinn 2009, 2017, 2018, Bicknell & Paterson 2018, Bicknell & Pates 2020, Bicknell et al. 2018b, 2023, drill holes (Kowalewski et al. 2000, Hoffmeister 2002, Amano 2003, Hoffmeister et al. 2004, Vinn et al. 2021, gut contents (Richter 1992, Sues 1993, Jago et al. 2016, Zacaï et al. 2016, and coprolites (H€ antzschel et al. 1968, Hunt 1992, Toom et al. 2020, Kimmig & Strotz 2017, Kimmig & Pratt 2018, Knaust 2020, Hunt & Lucas 2021 all represent useful evidence of predation. These different records present varying degrees of insight into possible trophic interactions, with the rarer specimens (such as prey within gut contents) presenting much more palaeoecological information (Babcock 1993, Zacaï et al. 2016, Bicknell & Paterson 2018. ...
Evidence of successful predation or scavenging in the fossil record represents important palaeobiological data to more thoroughly understanding extinct ecosystems. Shelly coprolites are particularly useful indications of durophagous predation in deposits, as they can have a higher preservational potential than their producers. Here we present a new shelly coprolite from the Silurian (Přídolí) Wallace Shale of New South Wales, Australia. This specimen contains abundant fragments of the trilobite Denckmannites rutherfordi Sherwin, 1968 that show limited disarticulation across exoskeletal sections. We propose that a pterygotid eurypterid was the most likely producer of this coprolite, although trilobites and fishes are not completely excluded as possible trace-makers. In documenting this specimen, we highlight that the Wallace Shale likely preserves a more complex palaeoecosystem than previously thought and renewed efforts to understand this deposit are needed in light of this new insight.
R.D.C. Bicknell [rdcbicknell@gmail.com], Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales, 2351, Australia;
P.M. Smith [Patrick.Smith@austmus.gov.au], Palaeontology Department, Australian Museum Research Institute, Sydney, New South Wales, 2010, Australia; Department of Biological Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia;
J. Kimmig [julien.kimmig@smnk.de], Abteilung Geowissenschaften, Staatliches Museum für Naturkunde Karlsruhe, Karlsruhe, 76133, Germany.
... Malformed fossils present insight into how extinct forms responded to developmental, parasitic, and injury-related complications (Owen, 1985;Babcock, 1993;Klompmaker et al. 2019;De Baets et al. 2022). Such specimens have been particularly useful for understanding facets of extinct arthropod groups (Babcock, 2003), including chelicerates, crustaceans, and trilobites (Owen, 1985;Klompmaker et al. 2013;Bicknell et al. 2018cBicknell et al. , 2022bMitov et al. 2021;De Baets et al. 2022). The most commonly documented malformed arthropod fossils are trilobitesa record that reflects their biomineralized exoskeleton (Babcock, 2003(Babcock, , 2007Fatka et al. 2015;Bicknell et al. 2022d). ...
... Most malformed genal spines are represented by disrupted borders (e.g. Chatterton, 1971;Cowie & McNamara, 1978;Owen, 1985;Babcock, 1993;Bicknell et al. 2018c), abnormal cephalic fringes (Owen, 1983), or bifurcating genal spines (Owen, 1985). Complete removal (Kay, 1937) and recovery (Sinclair, 1947;Hessin, 1988;Bicknell et al. 2022c) of genal spines is exceedingly rare, as reflected by the single Estaingia bilobata specimen documented here. ...
Malformed trilobite specimens present important insight into understanding how this extinct arthropod group recovered from developmental or moulting malfunctions, pathologies, and injuries. Previously documented examples of malformed trilobite specimens are often considered in isolation, with few studies reporting on multiple malformations in the same species. Here we report malformed specimens of the ellipsocephaloid trilobite Estaingia bilobata from the Emu Bay Shale Konservat-Lagerstätte (Cambrian Series 2, Stage 4) on Kangaroo Island, South Australia. Ten malformed specimens exhibiting injuries, pathologies, and a range of tera-tologies are documented. Furthermore, five examples of mangled exoskeletons are presented, indicative of predation on E. bilobata. Considering the position of malformed and normal specimens of E. bilobata in bivariate space, we demonstrate that the majority of malformed specimens cluster among the larger individuals. Such specimens may exemplify larger forms successfully escaping predation attempts, but could equally represent individuals exhibiting old injuries that were made during earlier (smaller) growth stages that have healed through subsequent moulting events. The available evidence from the Emu Bay Shale suggests that this small, extremely abundant trilobite likely played an important role in the structure of the local ecosystem, occupying a low trophic level and being preyed upon by multiple durophagous arthropods. Furthermore, the scarcity of malformed E. bilobata specimens demonstrates how rarely injuries, developmental malfunctions, and pathological infestations occurred within the species.
... Horseshoe crabs (Xiphosurida) have been extensively studied by both biologists and palaeontologists (Bicknell and Pates 2020). As such, the anatomical (Owen 1872;Lankester 1881;Patten 1894;Shultz 2001;Bicknell et al. 2018aBicknell et al. , 2018cBicknell and Pates 2019a), biochemical (Kaplan et al. 1977), biomechanical (Bicknell et al. 2018b;Razak and Kassim 2018), developmental (Sekiguchi et al. 1988;Farley 2010;Kaiser and Schoppe 2018), ecological (Sokoloff 1978;Shuster Jr. 1982;Dietl et al. 2000;Shuster Jr. and Sekiguchi 2009;Botton et al. 2010;Akbar John et al. 2012;Fairuz-Fozi et al. 2018), genetic (Sokoloff 1978;Obst et al. 2012), morphometric (Riska 1981;Vijayakumar et al. 2000;Srijaya et al. 2010;Bicknell 2019;Bicknell and Pates 2019b;Bicknell et al. 2019d, physiological (Redmond et al. 1982), and palaeontological (Woodward 1879;Fisher 1984;Selden and Siveter 1987;Hauschke and Wilde 1991;Bicknell et al. 2018dBicknell et al. , 2019c aspects of horseshoe crabs are well documented. Despite this extensive research program, at least one facet of horseshoe crabs anatomy-abnormalities-has been underexplored. ...
... Despite this extensive research program, at least one facet of horseshoe crabs anatomy-abnormalities-has been underexplored. Currently, van der Meer Mohr (1935) , Shuster Jr. (1982), Jell (1989), Bicknell et al. (2018d), and Bicknell and Pates (2019a) are the main documents considering abnormal xiphosurids. Prior to the recent research, the majority of documented abnormalities were recorded for the telson (Shuster Jr. 1982;Botton and Loveland 1989;Shuster Jr. and Sekiguchi 2004), with rarer examples for the cephalothorax (=prosoma) and thoracetron (=opisthosoma) (Jell 1989;Brockmann 1990;Schaller et al. , 2005. ...
... Prior to the recent research, the majority of documented abnormalities were recorded for the telson (Shuster Jr. 1982;Botton and Loveland 1989;Shuster Jr. and Sekiguchi 2004), with rarer examples for the cephalothorax (=prosoma) and thoracetron (=opisthosoma) (Jell 1989;Brockmann 1990;Schaller et al. , 2005. Revised interest in documenting abnormal specimens, especially through using museum collections, has produced a larger summary of horseshoe crabs with malformations (Bicknell et al. 2018d;Bicknell and Pates 2019a). This has extended to palaeontological examples, highlighting that injuries and malformations observed today have a fossil record extending back to at least the Carboniferous (Bicknell et al. 2018d). ...
Xiphosurids are marine chelicerates that have been subject to extensive biological and palaeontological scrutiny over the past two centuries. This research effort is fuelled by the unique anatomical and physiological characteristics of the group, a long fossil record with conserved morphology, and use as modern analogues for understanding extinct arthropod groups. Despite this extensive literature, abnormal xiphosurid specimens are somewhat understudied. Recent studies have documented malformed specimens, the majority of which are attributed to injuries and developmental complications. To augment this recent research, we present records of Limulus polyphemus and Tachypleus tridentatus with malformed with malformed appendages, cephalothoraces, thoracetrons, and telsons. Causes of abnormalities are discussed and attributed to moulting issues and injuries. Three new examples of abnormal fossil xiphosurids are also presented: Euproops danae and Mesolimulus walchi specimens with cephalothoracic injuries and one specimen of M. walchi displaying a curved telson. We conclude that documenting abnormalities within populations may aid identification of spawning areas that require conservation attention. These oddities represent a potential avenue to minimize the population threats currently facing these unique chelicerates.KeywordsAbnormalitiesXiphosurida
Limulus polyphemus
Tachypleus tridentatus
Euproops danae
Mesolimulus walchi
Conservation
... Hughes et al., 2021, 2021b. One such deposit is the Cambrian Series 2 (Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstätte on Kangaroo Island in South Australia that contains abundant, articulated trilobites (Paterson and Jago, 2006;Paterson et al., 2016;Holmes et al., 2020Holmes et al., , 2021aHolmes et al., , 2021b, some with previously recorded healed injuries (Conway Morris and Jenkins, 1985;Nedin, 1999;Bicknell and Paterson, 2018;Bicknell et al., 2018c;Bicknell and Pates, 2019). Here, we document and explore injury patterns in two species of Redlichia Cossmann, 1902 from the EBS Konservat-Lagerstätte (R. takooensis Lu, 1950 andR. ...
... Injury-"[R]esult of physical breakage of the exoskeleton" (Babcock, 1993, p. 220) when the organism was alive. This can reflect either an attack, accidental injury, or complications during moulting (Bicknell et al., 2018c;Bicknell and Pates, 2020). An injury should not extend across the entire specimensuch breakages are likely due to postmortem processes, such as sediment compaction (Leighton, 2011). ...
... An injury should not extend across the entire specimensuch breakages are likely due to postmortem processes, such as sediment compaction (Leighton, 2011). Injuries are typically characterised by: an L-, U-, V-, or W-shaped break across a large part of the exoskeleton, such as the cephalon or several adjacent thoracic segments (following Bicknell et al., 2018c and; or a 'single segment injury' (SSI; sensu Pates, 2020). Injuries may also be bilaterally expressed (Babcock, 2007), but the injuries on each side may be independent (i.e. ...
The Cambrian explosion represents the rapid emergence of complex marine ecosystems on Earth. The propagation
of predator-prey interactions within these systems was almost certainly one of the major drivers of this
evolutionary event, sparking an arms race that promoted the proliferation of biomineralised exoskeletons and
shells, and the evolution of the first durophagous (shell-crushing) predators. The most commonly documented
evidence of Cambrian durophagous predation comes from injured trilobites. However, quantitative analysis
based on multiple specimens from single localities is lacking. Such studies are required to reveal the dynamics of
ancient predator-prey systems at fine ecological scales (e.g. at the population or community level). This study
documents injured specimens of two trilobite species, Redlichia takooensis and Redlichia rex, from the Emu Bay
Shale Konservat-Lagerst¨atte (Cambrian Series 2, Stage 4) on Kangaroo Island, South Australia. A total of 38 injured
specimens exhibiting various healed cephalic and thoracic injuries are documented, in addition to the mangled
remains of two individuals that probably resulted from the activities of a durophagous predator or scavenger.
Specimens of both species show that most injuries are located on the posterior portion of the thorax, indicating
that predators preferentially attacked from behind and/or prey individuals presented the posterior of the trunk
towards the predator when threatened or fleeing. The larger sample of injured R. takooensis shows that while
unilateral injuries are more common than bilateral ones, there is no evidence for a left- or right-side bias,
contrasting with previous suggestions that Cambrian trilobites exhibit right-sided injury stereotypy. Comparing
the position of injured and non-injured R. takooensis and R. rex in bivariate space, we illustrate that injured
specimens of both species typically represent some of the largest individuals of these taxa. This suggests that
smaller individuals were completely consumed during an attack and/or larger individuals were more likely to
survive an attack and thus record a healed injury. We argue that R. rex, rather than radiodonts, was likely the
chief producer of exoskeletal injuries and large shelly coprolites in the Emu Bay Shale biota, and represents one
of the earliest cannibalistic trilobites.
... Hughes et al., 2021, 2021b. One such deposit is the Cambrian Series 2 (Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstätte on Kangaroo Island in South Australia that contains abundant, articulated trilobites (Paterson and Jago, 2006;Paterson et al., 2016;Holmes et al., 2020Holmes et al., , 2021aHolmes et al., , 2021b, some with previously recorded healed injuries (Conway Morris and Jenkins, 1985;Nedin, 1999;Bicknell and Paterson, 2018;Bicknell et al., 2018c;Bicknell and Pates, 2019). Here, we document and explore injury patterns in two species of Redlichia Cossmann, 1902 from the EBS Konservat-Lagerstätte (R. takooensis Lu, 1950 andR. ...
... Injury-"[R]esult of physical breakage of the exoskeleton" (Babcock, 1993, p. 220) when the organism was alive. This can reflect either an attack, accidental injury, or complications during moulting (Bicknell et al., 2018c;Bicknell and Pates, 2020). An injury should not extend across the entire specimensuch breakages are likely due to postmortem processes, such as sediment compaction (Leighton, 2011). ...
... An injury should not extend across the entire specimensuch breakages are likely due to postmortem processes, such as sediment compaction (Leighton, 2011). Injuries are typically characterised by: an L-, U-, V-, or W-shaped break across a large part of the exoskeleton, such as the cephalon or several adjacent thoracic segments (following Bicknell et al., 2018c and; or a 'single segment injury' (SSI; sensu Pates, 2020). Injuries may also be bilaterally expressed (Babcock, 2007), but the injuries on each side may be independent (i.e. ...
The Cambrian explosion represents the rapid emergence of complex marine ecosystems on Earth. The propagation of predator-prey interactions within these systems was almost certainly one of the major drivers of this evolutionary event, sparking an arms race that promoted the proliferation of biomineralised exoskeletons and shells, and the evolution of the first durophagous (shell-crushing) predators. The most commonly documented evidence of Cambrian durophagous predation comes from injured trilobites. However, quantitative analysis based on multiple specimens from single localities is lacking. Such studies are required to reveal the dynamics of ancient predator-prey systems at fine ecological scales (e.g. at the population or community level). This study documents injured specimens of two trilobite species, Redlichia takooensis and Redlichia rex, from the Emu Bay Shale Konservat-Lagerstätte (Cambrian Series 2, Stage 4) on Kangaroo Island, South Australia. A total of 38 injured specimens exhibiting various healed cephalic and thoracic injuries are documented, in addition to the mangled remains of two individuals that probably resulted from the activities of a durophagous predator or scavenger. Specimens of both species show that most injuries are located on the posterior portion of the thorax, indicating that predators preferentially attacked from behind and/or prey individuals presented the posterior of the trunk towards the predator when threatened. The larger sample of injured R. takooensis shows that while unilateral injuries are more common than bilateral ones, there is no evidence for a left- or right-side bias, contrasting with previous suggestions that Cambrian trilobites exhibit right-sided injury stereotypy. Comparing the position of injured and non-injured R. takooensis and R. rex in bivariate space illustrates that injured specimens of both species typically represent some of the largest individuals of these taxa. This suggests that smaller individuals were completely consumed during an attack and/or larger individuals were more likely to survive an attack and thus record a healed injury. We argue that R. rex was likely the chief producer of exoskeletal injuries and large shelly coprolites in the Emu Bay Shale biota, and represents one of the earliest cannibalistic trilobites.
... Predation on fossil arthropods is most commonly quantified through evidence of failed predation, typically abnormal prey items. The lion's share of these are trilobites, with rarer examples known in crustaceans (Klompmaker et al. 2019) and chelicerates (Bicknell et al. 2018c;Klompmaker et al. 2019). This dominance reflects the biomineralised exoskeletons produced by trilobites, which aided preservation and the record of injuries (Webster 2007;Bicknell and Pates 2020). ...
Trilobite malformations are often ascribed to failed predation and represent key evidence for Paleozoic arthropod predator–prey systems. A large number of malformed trilobites are known to Cambrian-aged deposits and have recently been discussed at length. Conversely, most post-Cambrian records are noted as anecdotal points within larger taxonomic works. To expand the consideration of post-Cambrian injured trilobites, we report two malformed Ogygiocarella debuchii specimens from the Middle Ordovician of Wales and a heavily malformed Spiniscutellum umbelliferum specimen from the Early Devonian of the Czech Republic. These specimens are considered to represent records of failed predation. In considering these specimens, we explore possible injury-making groups, in particular noting that S. umbelliferum was likely prey for multiple apex predators. Continued examination of injured trilobites represents the main direction for uncovering how this iconic group of biomineralised arthropods interacted with higher tropic levels within Paleozoic foodwebs.
... Understanding abnormalities can inform our understanding of recovery from injuries and present insight into poor environmental or ecological conditions [Bicknell, Pates, 2019a]. Presently, the key studies of abnormal xiphosurids are van der Meer Mohr [1935], Shuster Jr. [1982, Jell [1989], Bicknell et al. [2018], and Bicknell & Pates [2019a]. However, most of these studies have considered museum collections and only Bicknell & Pates [2019a] documented abnormal Carcinoscorpius rotundicauda specimens. ...
... Five abnormal specimens were collected for this study and placed in 70% ethanol solution for photography in lab with a Nikon 5600 DSLR (18-55 mm lens). Specimens were considered abnormal if they had deformed/missing exoskeleton sections, malformed growths and generally non-standard exoskeletal morphologies [sensu Owen, 1985;Bicknell et al., 2018;Bicknell, Pates, 2019a, 181 specimens (87 females, 63 males and 31 juveniles). The most common abnormalities were prosomal (n=19), thoracetronic (n=15), and telsonic (n=10). ...
... Comparing the documented abnormalities to other malformed horseshoe crabs [Shuster Jr., 1982;Bicknell et al., 2018;Bicknell, Pates, 2019] and to trilo- Рис. 16. ...
Xiphosurida are iconic group of marine chelicerates that have been subject to more than
200 years of neonatological and palaeontological scrutiny. However, recent studies have identified that there is very little data concerning abnormal specimens, and even less data on wild populations. The present study aims to rectify this dearth of information by documenting abnormal Carcinoscorpius rotundicauda from the Indian Sundarbans. We illustrated 36 abnormal specimens and attribute the abnormalities to injuries. Morphological differences between injured relative to noninjured individuals are considered and possible causes for injuries are discussed. Major anthropogenic threats are highlighted, with the aim of illustrating the key directions needed to conserve the unique mangrove horseshoe crab in the Indian Sundarbans.
