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Clarkeiteuthis montefiorei ( B uckman , 1880) n. comb., Charmouth Mudstone Formation (Upper Sinemurian), Dorset (UK). A – Overview, MB C3603, original of N aef (1922: 179). Scale equals 10 mm. B – Arm crown, MB C3604, original of N aef (1922: 179). C – Close-up of 5B to show the hooklets. Scales equal 1 mm. 

Clarkeiteuthis montefiorei ( B uckman , 1880) n. comb., Charmouth Mudstone Formation (Upper Sinemurian), Dorset (UK). A – Overview, MB C3603, original of N aef (1922: 179). Scale equals 10 mm. B – Arm crown, MB C3604, original of N aef (1922: 179). C – Close-up of 5B to show the hooklets. Scales equal 1 mm. 

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For Phragmoteuthis conocauda (Quenstedt, 1849) from the Lower Toarcian Posidonia Shale (South Germany) and Phragmoteuthis montefiorei (Buckman, 1880) from the Upper Sinemurian Charmouth Mudstone Formation (Dorset, UK), a new belemnoid genus, Clarkeiteuthis, is introduced. Clarkeiteuthis significantly differs from Phragmoteuthis by the absence of a...

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... This bed, although bituminous, does not show lamination and possibly represented a rather soupy substrate. The ʻKoblenzerʼ in the vicinity of Holzmaden is especially well-known for its articulated belemnite specimens such as the present one (Reitner & Urlichs, 1983;Riegraf & Hauff, 1983;Schlegelmilch, 1998) besides numerous other coleoids (which belong to the genera Clarkeiteuthis and Chondroteuthis; Fuchs & Weis, 2008;Fuchs et al., 2013) as well as nicely preserved decapod crustaceans of the genera Uncina, Proeryon, and Tonneleryon (Audo, 2016;Audo et al., 2020;Schweigert et al., 2003). Vertebrate remains comprise fishes, ichthyosaurs and marine crocodiles, but these are less frequently found, because the Koblenzer bed underlies the Fleins bed, for which the Posidonia Shale is quarried, and this bed was therefore rarely exposed (Dieter Weber, pers. ...
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Especially in Lagerstätten with exceptionally preserved fossils, we can sometimes recognize fossilized remains of meals of animals. We suggest the term leftover fall for the event and the term pabulite for the fossilized meal when it never entered the digestive tract (difference to regurgitalites). Usually, pabulites are incomplete organismal remains and show traces of the predation. Pabulites have a great potential to inform about predation as well as anatomical detail, which is invisible otherwise. Here, we document a pabulite comprising the belemnite Passaloteuthis laevigata from the Toarcian of the Holzmaden region. Most of its soft parts are missing while the arm crown is one of the best preserved that is known. Its arms embrace an exuvia of a crustacean. We suggest that the belemnite represents the remnant of the food of a predatory fish such as the shark Hybodus .
... The hooks of Phragmoteuthis montefiorei illustrated by Donovan (2006, text-figs 1, 2) appear to have a slender shaft (perpendicular to the base) and a slightly curved uncinus, but are particularly characterised by inflated bases that may appear to be slightly bi-lobate (Fuchs and Hoffmann, 2017;Hart et al., 2019, Fig. 8(a,b)). In a recent review of this group, Fuchs et al. (2013) have now included some Lower Jurassic phragmoteuthids in a new genus, Clarkeiteuthis. Their paper clearly shows that C. conocauda (Fuchs et al., 2013, Fig. 3) has paired hooks, which look to be identical, with characteristically inflated bases (Hart et al., 2019, Fig. 8,(c, d)). ...
... The fish companion of Specimen GSM 87477 belongs to a species that has been removed from Pholidophorus and it is currently interpreted in a new genus named Dorsetichthys Arratia, 2013, with one species, D. bechei (Agassiz, 1837), which is placed in its own family (Nelson et al., 2016;Arratia, 2017). Several members of the non-monophyletic genus "Pholidophorus" sensu Arratia Fuchs et al. (2013) for Clarkeiteuthis conocaudawhich shows both elements of the pairs being almost identicalbeing rather closer to that figured by Hyde (2012) where the pairs or composed of different looking elements. Scale in cm. ...
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The Jurassic succession of the Wessex Basin, especially that cropping out along the Dorset Coast, contains important Lagerstätten for coleoid cephalopods. The Blue Lias and Charmouth Mudstone formations have, since the nineteenth century, provided large numbers of important body fossils that inform our knowledge of coleoid palaeontology. In many of these mudstones specimens of palaeobiological significance have been found, especially those with the arms and hooks with which the living animals caught their prey. This is particularly true in the case of a specimen of Clarkeiteuthis sp. cf. C. montefiorei (Buckman, 1879) found in the nineteenth century with a fish in its jaws and which appears to have caused the death, and subsequent preservation, of both animals.
... A, Aulacoceras sulcatum (Aulacoceratida), Upper Triassic (Carnian-Norian), Timor; longitudinal section; pr, primordial rostrum; ro, rostrum; other abbreviations as in Fig. 2 slightly longer (approx. 60% of the total shell length) than the phragmocone (Fuchs et al. 2013a;Jenny et al. 2019). We therefore assumed that the length of early ontogenetic body chambers/proostraca were between 40% and 50% of the total shell length. ...
Article
Coleoid cephalopods exhibited two distinct reproductive strategies, resulting in small pelagic and large demersal hatchlings, both in the geologic past and recently. In ectocochleate cephalopods, the hatching event is recorded in shell structures (e.g., nepionic constrictions, ultrastructural shifts, or ornamentation differences). In contrast, well-defined hatching markers do not exist on coleoid shells. Changes in septal spacing may be evidence of hatching (e.g., some extant sepiids), but not in all fossil groups. In the present study, we subdivide the early ontogenetic shells of phragmocone-bearing coleoids (belemnoids, spirulids, and sepiids) into key architectural stages and describe their reference to the hatching event. Belemnoids exhibit three key stages, the second of which is here considered to occur shortly before or after hatching. In spirulids and sepiids, there is only one key stage. In Mesozoic belemnoids, spirulids, and sepiids, hatching accordingly occurred with a total shell length of less than 2 mm, which corresponds to mantle lengths of small planktonic hatchlings. Production of small pelagic hatchlings and thus small eggs was therefore the dominant reproductive strategy within the Coleoidea. The first evidence of enlarged hatchlings appeared during the Maastrichtian in Groenlandibelus. During the Eocene, the large-egg strategy apparently became more widespread, particularly in belosaepiids.
... From this point of view, it is not surprising that the first rostrum-bearing belemnite preserved with soft-parts was found in the Posidonienschiefer 6,18,19 . Some other cephalopods also show anatomical details of soft tissues that are usually not preserved (e.g., digestive tract in ammonites 6 ; musculature and gills in non-belemoid coleoids [20][21][22]. Despite the extreme scarcity of cephalopods preserved with their prey, the specimen presented here was never described in detail and only figured once without detailed discussion 23 . ...
... The originally chitinous proostracum is only partially fossilized, 90 mm long and 5-9 mm wide. Taking the proportions of the animal into account, the proostracum should be 80 up to 110 mm long 21 . Possibly, only the thicker posterior parts are preserved either due to taphonomic alteration or loss during preparation. ...
... Just anterior to the proostracum, two patches of the muscular mantle are visible. They have an oval shape and show the transverse striation, which is characteristic for Mesozoic coleoids and thus also for those of the Posidonienschiefer 6,19,21 . Both patches are 26 mm long and 14 mm wide and end just posterior of the jaws. ...
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We describe four complete specimens of the early squid-like cephalopod Clarkeiteuthis conocauda from the Toarcian Posidonienschiefer (Jurassic) each preserved with the bony fish Leptolepis bronni in its arms. Based on the arrangement of prey and predator, we suggest that the cephalopods caught and killed the fishes while still in well-oxygenated waters and then descended into oxygen-depleted water layers (distraction sinking) where the cephalopod suffocated. This explains the exceptional preservation, for which the Posidonienschiefer is famed. This association raises the question for the hunting behaviour of belemnoid Coleoidea. Using the proportions of soft and skeletal body parts of diplobelids and belemnitids, we estimated their body mass and buoyancy and determined the centres of mass and buoyancy. These two points were very close to each other in belemnitids, implying a low hydrodynamic stability (when ignoring the fins), while in diplobelids, the distance between those centres was greater. This suggests that diplobelids usually assumed an oblique to vertical orientation of the body axis while belemnitids could effortlessly achieve a horizontal orientation of their body. Presuming larger fins were attached to the bigger belemnitid rostra, belemnitids were better swimmers and perhaps pursuit predators while diplobelids rather ambushed their prey.
... Moreover, workers derived the Sepiida from breviconic diplobelids such as Conoteuthis orbigNy, 1842, or Vectibelus Jeletzky, 1981 to the presence of distinctly inclined septa (Meyer, 1993;hewitt & Jagt, 1999;Fuchs, keupp, & wiese, 2012). Although unknown in most diplobelid genera, in situ arm hooks recorded in putative diplobelids Chondroteuthis boDe, 1933(hoFFMaNN, Fuchs, & weiNkauF, 2016 and Clarkeiteuthis Fuchs, DoNoVaN, & keupp, 2013, as well as isolated hooks in Cretaceous sediments without belemnitid rostra suggest that diplobelid arms were likewise equipped with hooks (Fuchs, reich, & wiese, 2004; see Treatise Online 91, Chapter 10). Fossilized soft parts are virtually absent in unambiguous diplobelids, except for medio-dorsal, soft-tissue attachment scars on the inner surface of each chamber. ...
... Moreover, workers derived the Sepiida from breviconic diplobelids such as Conoteuthis orbigNy, 1842, or Vectibelus Jeletzky, 1981 to the presence of distinctly inclined septa (Meyer, 1993;hewitt & Jagt, 1999;Fuchs, keupp, & wiese, 2012). Although unknown in most diplobelid genera, in situ arm hooks recorded in putative diplobelids Chondroteuthis boDe, 1933(hoFFMaNN, Fuchs, & weiNkauF, 2016 and Clarkeiteuthis Fuchs, DoNoVaN, & keupp, 2013, as well as isolated hooks in Cretaceous sediments without belemnitid rostra suggest that diplobelid arms were likewise equipped with hooks (Fuchs, reich, & wiese, 2004; see Treatise Online 91, Chapter 10). Fossilized soft parts are virtually absent in unambiguous diplobelids, except for medio-dorsal, soft-tissue attachment scars on the inner surface of each chamber. ...
... The latter misinterpretation also fundamentally influenced the argumentation of crick(1902,1907). Although a complete arm crown of C. montefiorei is still unknown, numerous arm crowns of C. conocauda characterized by identical hook shapes, clearly imply the existence of ten subequal and hookbearing arms (Donovan, 2006;Fuchs, Donovan, & keupp, 2013). Fortunately, riegraF and reitner (1979) prevented new confusion when they again exposed faked " soft-part belemnites " (see Treatise Online, Part M, Chapter 22). ...
... Assumptions of ten arms in the Phragmoteuthida were based on Clarkeiteuthis conocauda and on ?Phragmoteuthis ticinensis r i e B e r , 1 9 7 0. However, the former taxon has been recently reassigned from Phragmoteuthida to Diplobelida (Fuchs, Donovan, & keupp, 2013). Similarly, current phragmoteuthid affiliations of the latter taxon are still uncertain since diagnostic shell characters are unknown.In general, hook pairs are equally scattered along each arm and complementary hooks are usually of the same size and shape (Fig. 3–5,Fig. ...
... The hooklets also bear a resemblance to the arm hooks of the late Triassic Phragmoteuthis bisinuata (Doguzhaeva et al., 2007, fig. 2C;Fuchs et al., 2013, fig. 4E), allowing for some post-mortem flattening. ...
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The Late Triassic Rhaetian stage is perhaps best known in south-west Britain for the bone beds of the Westbury Formation, but there are other fossil-rich horizons within this and the underlying Blue Anchor Formation. Samples from a borehole drilled at the Filton West Chord, and collected from exposures near Bristol Parkway railway station, have yielded significant fossil material from both of these formations. The assemblage recovered from the Blue Anchor Formation is similar to those from the lower Westbury Formation, yielding roughly equal proportions of chondrichthyans and osteichthyans. Assemblages recovered from the Westbury Formation are typical of those from the upper Westbury Formation, in being dominated by osteichthyans. The borehole samples have produced the first recorded evidence of crinoids in the British Triassic, and the first evidence of coleoid cephalopods, in the form of grasping hooklets, from the Rhaetian, and indeed the first from the British Triassic.
... Complete or incomplete arm crowns associated with the remaining parts of the belemnoid specimen provide important paleobiological insights, particularly with respect to functional morphology, systematics, and taxonomy. Examples include the Late Triassic Phragmoteuthis (Rieber 1970;Doguzhaeva et al. 2007); Early Jurassic Sueviteuthis (Reitner and Engeser 1982), Acrocoelites, Passaloteuthis (Reitner and Urlichs 1983), and Clarkeiteuthis (Quenstedt 1849;Riegraf 1996;Fuchs et al. 2013a,b; see Garassino and Donovan [2000] for an extended list); and Middle to Late Jurassic Belemnotheutis (Owen 1844; Donovan and Crane 1992), Acanthoteuthis (Engeser and Reitner 1981), Winkleriteuthis (Fuchs et al. 2013a) and Hibolithes (Klug et al. 2010). Individuals of the above-mentioned species develop arms of similar length, and their arms are equipped with micro-hooks of similar shape. ...
... The monotypic genus Chondroteuthis is characterized by the absence of a solid and calcitic rostrum proper and by a narrow, long, spatulate proostracum, which is slightly FORM AND FUNCTION OF BELEMNOID ARM HOOKS longer than the orthoconic phragmocone (ratio phragmocone length:total shell length~0.4). With respect to shell morphologies, Chondroteuthis is closest to the coeval genus Clarkeiteuthis, but differs significantly in hook morphology (Fuchs et al. 2013a). Jeletzky (1966) and other workers regarded Chondroteuthis as a member of the belemnitid suborder Belemnotheutidina, but owing to the presence of a conspicuously narrow proostracum, we follow Engeser (1995), who first placed Chondroteuthis within the order Diplobelida. ...
... First, we provide for the first time direct evidence for the existence of 10 arms of equal length in Chondroteuthis. Second, we observed that hooks in Chondroteuthis are arranged in a single row, which is in contrast to the biserial arrangement in all other known belemnoid taxa with articulated arm crowns (e.g., compare with Engeser and Clarke 1988;Fuchs et al. 2010Fuchs et al. , 2013a. According to the uniserial arrangement of hooks and the assumed maximum number of hooks per arms (i.e., about 20-40), in Chondroteuthis the maximum number of hooks per arm crown ranges between 200 and 400 micro-hooks. ...
Article
Chitinous arm hooks (onychites) of belemnoid coleoid cephalopods are widely distributed in Mesozoic sediments. Due to their relative abundance and variable morphology compared with the single, bullet-shaped, belemnite rostrum, arm hooks came into the focus of micropaleontologists as a promising index fossil group for the Jurassic–Cretaceous rock record and have been the target of functional, ecological, and phylogenetic interpretations in the past. Based on three well-preserved arm crowns of the Toarcian diplobelid Chondroteuthis wunnenbergi, we analyzed the shape of a total of 87 micro-hooks. The arm crown of Chondroteuthis is unique in having uniserial rather than biserial hooks. The first application of elliptic Fourier shape analysis to the arm weapons of belemnoid coleoids allows for the distinction of four micro-hook morphotypes and the quantification of shape variation within these morphotypes. Based on the best-preserved arm crown, we reconstructed the distribution of morphotypes within the arm crown and along a single arm. Our quantitative data support former observations that smaller hooks were found close to the mouth and at the most distal arm parts, while the largest hooks were found in the central part of the arm crown. Furthermore, we found a distinct arm differentiation, as not every arm was equipped with the same hook morphotype. Here, we report the functional specialization of the belemnoid arm crown for the first time and speculate about the potential function of the four morphotypes based on comparisons with modern cephalopods. Our analyses suggest a highly adapted functional morphology and intra-individual distribution of belemnoid hooks serving distinct purposes mainly during prey capture.
... Chitinous arm hooks of belemnoid coleoids are widely distributed in Mesozoic sediments and are used as index fossils for the Jurassic-Cretaceous rock record for functional, ecological and phylogenetic interpretations (e.g., REITNER & ENGESER 1982;FUCHS et al. 2013;HAMMER et al. 2013). ...
Poster
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Chitinous arm hooks (onychites) of belemnoid coleoids are widely distributed in Mesozoic sediments. Due to their relative abundance and variable morphology compared to the single, bullet-shaped belemnite rostrum, arm hooks came into the focus of micropalaeontologist as a promising index fossil group for the Jurassic–Cretaceous rock record and have been the target of functional, ecological, and phylogenetic interpretations in the past (e.g. Reitner & Engeser 1982; Fuchs et al. 2013; Hammer et al. 2013). Based on three well-preserved arm crowns of the Toarcian diplobelid Chondroteuthis wunnenbergi, we analyzed the shape of a total of 87 micro-hooks. The arm crown of Chondroteuthis is unique in having uniserial (rather than biserial) hooks. The first application of elliptic Fourier shape analysis to the arm weapons of belemnoid coleoids allows for the distinction of four micro-hook morphotypes and the quantification of shape variation within these morphotypes. Based on the best preserved arm crown, we reconstructed the distribution of morphotypes within the arm crown as well as along a single arm. Our quantitative data support former observations that smaller hooks were found close to the mouth and at the most distal arm parts, while the largest hooks were found in the central part of the arm crown. Furthermore, we found a distinct arm differentiation, as not every arm was equipped with the same hook-morphotypes. Here, we report the functional specialisation of the belemnoid arm crown for the first time and speculate about the potential function of the four morphotypes. Our analyses suggest a highly adapted functional morphology and intra-specimen individual distribution of belemnoid hooks, serving distinct purposes mainly during prey capture, prey digestion, as well as reproduction. In this regard, hooks at the distal end of the arms show stronger curvature to effectively catch and hold the prey, while hooks closer to the belemnoids mouth are more suitable for prey dissection and for transporting food to the mouth. We speculate that this highly specialised arrangement is an adaptation of Chondroteuthis towards its uniserial hook-arrangement. This is supported by the fact that belemnoids with biserial hook armament do not show inter-individual changes in micro-hook morphology (Engeser 1987).