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Christian Klug - One of the best experts on this subject based on the ideXlab platform.
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Recent advances in heteromorph ammonoid palaeobiology
Biological Reviews, 2021Co-Authors: René Hoffmann, Joshua Slattery, Isabelle Kruta, Benjamin Linzmeier, Robert Lemanis, Aleksandr Mironenko, Stijn Goolaerts, Kenneth De Baets, David Peterman, Christian KlugAbstract:Heteromorphs are ammonoids forming a conch with detached whorls (open coiling) or non‐planispiral coiling. Such aberrant forms appeared convergently four times within this extinct group of cephalopods. Since Wiedmann's seminal paper in this journal, the palaeobiology of heteromorphs has advanced substantially. Combining direct evidence from their fossil record, indirect insights from phylogenetic bracketing, and physical as well as virtual models, we reach an improved understanding of heteromorph ammonoid palaeobiology. Their anatomy, buoyancy, locomotion, predators, diet, palaeoecology, and extinction are discussed. Based on phylogenetic bracketing with nautiloids and coleoids, heteromorphs like other ammonoids had 10 arms, a well‐developed brain, lens eyes, a buccal mass with a radula and a smaller upper as well as a larger lower jaw, and ammonia in their soft tissue. Heteromorphs likely lacked arm suckers, hooks, tentacles, a hood, and an Ink Sac. All Cretaceous heteromorphs share an aptychus‐type lower jaw with a lamellar calcitic covering. Differences in radular tooth morphology and size in heteromorphs suggest a microphagous diet. Stomach contents of heteromorphs comprise planktic crustaceans, gastropods, and crinoids, suggesting a zooplanktic diet. Forms with a U‐shaped body chamber (ancylocone) are regarded as suspension feeders, whereas orthoconic forms additionally might have consumed benthic prey. Heteromorphs could achieve near‐neutral buoyancy regardless of conch shape or ontogeny. Orthoconic heteromorphs likely had a vertical orientation, whereas ancylocone heteromorphs had a near‐horizontal aperture pointing upwards. Heteromorphs with a U‐shaped body chamber are more stable hydrodynamically than modern Nautilus and were unable substantially to modify their orientation by active locomotion, i.e. they had no or limited access to benthic prey at adulthood. Pathologies reported for heteromorphs were likely inflicted by crustaceans, fish, marine reptiles, and other cephalopods. Pathologies on Ptychoceras corroborates an external shell and rejects the endocochleate hypothesis. Devonian, Triassic, and Jurassic heteromorphs had a preference for deep‐subtidal to offshore facies but are rare in shallow‐subtidal, slope, and bathyal facies. Early Cretaceous heteromorphs preferred deep‐subtidal to bathyal facies. Late Cretaceous heteromorphs are common in shallow‐subtidal to offshore facies. Oxygen isotope data suggest rapid growth and a demersal habitat for adult Discoscaphites and Baculites. A benthic embryonic stage, planktic hatchlings, and a habitat change after one whorl is proposed for Hoploscaphites. Carbon isotope data indicate that some Baculites lived throughout their lives at cold seeps. Adaptation to a planktic life habit potentially drove selection towards smaller hatchlings, implying high fecundity and an ecological role of the hatchlings as micro‐ and mesoplankton. The Chicxulub impact at the Cretaceous/Paleogene (K/Pg) boundary 66 million years ago is the likely trigger for the extinction of ammonoids. Ammonoids likely persisted after this event for 40–500 thousand years and are exclusively represented by heteromorphs. The ammonoid extinction is lInked to their small hatchling sizes, planktotrophic diets, and higher metabolic rates than in nautilids, which survived the K/Pg mass extinction event.
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first record of a belemnite preserved with beaks arms and Ink Sac from the nusplingen lithographic limestone kimmeridgian sw germany
Lethaia, 2010Co-Authors: Christian Klug, Dirk Fuchs, Gunter Schweigert, Gerd DietlAbstract:Klug, C., Schweigert, G., Fuchs, D. & Dietl, G. 2009: First record of a belemnite preserved with beaks, arms and Ink Sac from the Nusplingen Lithographic Limestone (Kimmeridgian, SW Germany). Lethaia, 10.1111/j.1502-3931.2009.00203.x A recent discovery of an unusually preserved belemnite from Nusplingen comprises the extraordinarily rare remains of beaks and nearly in situ arm hooks, as well as the Ink Sac and an incomplete phragmocone. So far, Hibolithes semisulcatus (Munster, 1830) is the only belemnite known from the Nusplingen Lithographic Limestone (Upper Jurassic, Late Kimmeridgian, Beckeri Zone, Ulmense Subzone; SW Germany) that has the same phragmocone shape and size, and thus we assign the new specimen to this taxon. The rostrum was probably lost due to a lethal predation attempt in which the prey was killed but not entirely eaten. For the first time a specimen reveals details of the belemnite beak morphology, which we compare with the beaks of other Jurassic coleoids. This specimen presently represents the only known rostrum-bearing belemnite of post-Toarcian age with preserved non-mineralized body parts. With the new discovery, Nusplingen now represents the only locality which has yielded complete beak apparatuses from all major Jurassic cephalopod groups. □Beaks, Belemnitida, Coleoidea, Germany, Late Jurassic, morphology, taphonomy.
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An earliest Hettangian (Jurassic) belemnitid from Great Britain with a preserved proostracum
2010Co-Authors: Christian Klug, Dirk Fuchs, K Tanabe, Y Shigeta, T Sasaki, H HiranoAbstract:A new specimen of an earliest Hettangian (Jurassic) belemnite (Coeloidea, Cephalopoda) is described herein. It displays the complete, typically belemnitid proostracum, the Ink Sac with its duct, questionable remains of the nuchal cartilage, and half of the phragmocone. Since the apical part of the phragmocone is missing, it is unclear what kind of rostrum was present and a taxonomic assignment is thus impossible. This represents the earliest record of an undoubted belemnitid proostracum of clear stratigraphic affi nity.
A. Louise Allcock - One of the best experts on this subject based on the ideXlab platform.
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The Ink Sac clouds octopod evolutionary history
Hydrobiologia, 2014Co-Authors: Jan M. Strugnell, Mark D. Norman, Michael Vecchione, Michelle Guzik, A. Louise AllcockAbstract:Difficulties in elucidating the evolutionary history of the octopods have arisen from problems in identifying informative morphological characters. Recent classifications have divided the largest group, the incirrate octopods, into five groups. These include the pelagic superfamily Argonautoidea and three gelatinous pelagic families (Vitreledonellidae, Bolitaenidae, Amphitretidae). All benthic incirrate octopods have been accommodated in the family Octopodidae, itself divided into four subfamilies, Octopodinae, Eledoninae, Bathypolypodinae and Graneledoninae, which are defined by the presence or absence of an Ink Sac, and uniserial or biserial sucker arrangements on the arms. We used relaxed clock models in a Bayesian framework and maximum likelihood methods to analyse three nuclear and four mitochondrial genes of representatives from each of the previous subfamilies. Strong evidence indicates that the family Octopodidae is paraphyletic and contains the gelatinous pelagic families. The subfamilies of Octopodidae recognised in earlier works do not reflect evolutionary history. The following clades were supported in all analyses: (1) Eledone/Aphrodoctopus , (2) Callistoctopus / Grimpella / Macroctopus/Scaeurgus , (3) Abdopus / Ameloctopus/Amphioctopus / Cistopus/Hapalochlaena / Octopus , (4) Enteroctopus/Muusoctopus / Vulcanoctopus , (5) Vitreledonella / Japetella , (6) Southern Ocean endemic and deep-sea taxa with uniserial suckers. These clades form the basis for a suite of taxa assigned family taxonomic rank: Amphitretidae, Bathypolypodidae, Eledonidae, Enteroctopodidae, Megaleledonidae and Octopodidae sensu nov. They are placed within the superfamily Octopodoidea.
Marco Dischia - One of the best experts on this subject based on the ideXlab platform.
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a calcium calmodulin dependent nitric oxide synthase nmdar2 3 receptor subunits and glutamate in the cns of the cuttlefish sepia officinalis localization in specific neural pathways controlling the Inking system
Journal of Neurochemistry, 2001Co-Authors: Anna Palumbo, Anna Di Cosmo, Annarita Poli, Carlo Di Cristo, Marco DischiaAbstract:Abstract Chemical, biochemical, and immunohistochemical evidence is reported demonstrating the presence in the brain of the cuttlefish Sepia officinalis of a Ca2+-dependent nitric oxide synthase, NMDAR2/3 receptor subunits, and glutamate, occurring in neurons and fibers functionally related to the Inking system. Nitric oxide synthase activity was concentrated for the most part in the cytosolic fraction and was masked by other citrulline-forming enzyme(s). The labile nitric oxide synthase could be partially purified by ammonium sulfate precipitation of tissue extracts, followed by affinity chromatography on 2′, 5′-ADP-agarose and calmodulin-agarose. The resulting activity, immunolabeled at 150 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis by antibodies to rat neuronal nitric oxide synthase, depended on NADPH and tetrahydro-L-biopterin, and was inhibited by NG-nitro-L-arginine. NMDAR2/3 subunit-immunoreactive proteins migrating at 170 kDa could also be detected in brain extracts, along with glutamate (whole brain : 0.32 ± 0.03 μmol of glutamate/mg of protein ; optic lobes : 0.22 ± 0.04 ; vertical complex : 0.06 ± 0.06 basal lobes : 0.58 ± 0.04 ; brachial lobe : 0.77 ± 0.06 ; pedal lobe : 1.04 ± 0.08 ; palliovisceral lobe : 0.86 ± 0.05). Incubation of intact brains with 1.5 mM glutamate or NMDA or the nitric oxide donor 2-(N,N-diethylamino)diazenolate-2-oxide caused a fivefold rise in the levels of cyclic GMP, indicating operation of the glutamate-nitric oxide-cyclic GMP signaling pathway. Immunohistochemical mapping of Sepia CNS showed specific localization of nitric oxide synthase-like and NMDAR2/3-like immunoreactivities in the lateroventral palliovisceral lobe, the visceral lobe, and the pallial and visceral nerves, as well as in the sphincters and wall of the Ink Sac.
Jan M. Strugnell - One of the best experts on this subject based on the ideXlab platform.
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The Ink Sac clouds octopod evolutionary history
Hydrobiologia, 2014Co-Authors: Jan M. Strugnell, Mark D. Norman, Michael Vecchione, Michelle Guzik, A. Louise AllcockAbstract:Difficulties in elucidating the evolutionary history of the octopods have arisen from problems in identifying informative morphological characters. Recent classifications have divided the largest group, the incirrate octopods, into five groups. These include the pelagic superfamily Argonautoidea and three gelatinous pelagic families (Vitreledonellidae, Bolitaenidae, Amphitretidae). All benthic incirrate octopods have been accommodated in the family Octopodidae, itself divided into four subfamilies, Octopodinae, Eledoninae, Bathypolypodinae and Graneledoninae, which are defined by the presence or absence of an Ink Sac, and uniserial or biserial sucker arrangements on the arms. We used relaxed clock models in a Bayesian framework and maximum likelihood methods to analyse three nuclear and four mitochondrial genes of representatives from each of the previous subfamilies. Strong evidence indicates that the family Octopodidae is paraphyletic and contains the gelatinous pelagic families. The subfamilies of Octopodidae recognised in earlier works do not reflect evolutionary history. The following clades were supported in all analyses: (1) Eledone/Aphrodoctopus , (2) Callistoctopus / Grimpella / Macroctopus/Scaeurgus , (3) Abdopus / Ameloctopus/Amphioctopus / Cistopus/Hapalochlaena / Octopus , (4) Enteroctopus/Muusoctopus / Vulcanoctopus , (5) Vitreledonella / Japetella , (6) Southern Ocean endemic and deep-sea taxa with uniserial suckers. These clades form the basis for a suite of taxa assigned family taxonomic rank: Amphitretidae, Bathypolypodidae, Eledonidae, Enteroctopodidae, Megaleledonidae and Octopodidae sensu nov. They are placed within the superfamily Octopodoidea.
Anna Palumbo - One of the best experts on this subject based on the ideXlab platform.
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melanogenesis in the Ink gland of sepia officinalis
Pigment Cell Research, 2003Co-Authors: Anna PalumboAbstract:Among the various melanin-producing systems, the Ink gland of the cuttlefish (Sepia officinalis) has traditionally been regarded as a most convenient model system for the studies of melanogenesis. The Ink gland is a highly specialized organ with immature cells in the inner portion, from where the cells gradually mature, migrate towards the outer portion of the gland and become competent to produce melanin giving rise to particulate melanosomes. When cell maturation is complete, melanin is secreted into the lumen of the gland, accumulated into the Ink Sac and ejected on demand. Biochemical studies carried out over the past two decades have shown that the Ink gland contains a variety of melanogenic enzymes, including tyrosinase, a peculiar dopachrome rearranging enzyme (which catalyses the rearrangement of dopachrome to 5,6-dihydroxyindole) and a peroxidase (presumably involved in the later stages of melanin biosynthesis). These enzymes are functionally interactive in close subcellular compartments of Ink gland cells and appear to act in a concerted fashion during the process of melanogenesis in the mature portion of the gland. More recent studies have revealed that Ink production and ejection are affected and modulated by the N-methyl-d-aspartate (NMDA)–nitric oxide (NO)–cyclic GMP (cGMP) signalling pathway. Glutamate NMDA receptor and NO synthase, the enzyme responsible for the synthesis of NO, have been detected by biochemical and immunohistochemical techniques in immature Ink gland cells. Stimulation of NMDA receptors caused a marked elevation of cGMP levels, activation of tyrosinase and increased melanin synthesis in the mature portion of the gland, via the NO–guanylyl cyclase interaction. This signalling is also present in different regions of the nervous system in Sepia and in certain neural pathways controlling contraction of the Ink Sac sphincters and wall muscle in the ejection mechanism. Overall, these and other findings allowed elaboration of an improved model of melanin formation in Sepia, which underscores the complex interplay of melanogenic enzymes and regulatory factors, highlighting both the similarities and the differences with melanogenesis in mammals.
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a calcium calmodulin dependent nitric oxide synthase nmdar2 3 receptor subunits and glutamate in the cns of the cuttlefish sepia officinalis localization in specific neural pathways controlling the Inking system
Journal of Neurochemistry, 2001Co-Authors: Anna Palumbo, Anna Di Cosmo, Annarita Poli, Carlo Di Cristo, Marco DischiaAbstract:Abstract Chemical, biochemical, and immunohistochemical evidence is reported demonstrating the presence in the brain of the cuttlefish Sepia officinalis of a Ca2+-dependent nitric oxide synthase, NMDAR2/3 receptor subunits, and glutamate, occurring in neurons and fibers functionally related to the Inking system. Nitric oxide synthase activity was concentrated for the most part in the cytosolic fraction and was masked by other citrulline-forming enzyme(s). The labile nitric oxide synthase could be partially purified by ammonium sulfate precipitation of tissue extracts, followed by affinity chromatography on 2′, 5′-ADP-agarose and calmodulin-agarose. The resulting activity, immunolabeled at 150 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis by antibodies to rat neuronal nitric oxide synthase, depended on NADPH and tetrahydro-L-biopterin, and was inhibited by NG-nitro-L-arginine. NMDAR2/3 subunit-immunoreactive proteins migrating at 170 kDa could also be detected in brain extracts, along with glutamate (whole brain : 0.32 ± 0.03 μmol of glutamate/mg of protein ; optic lobes : 0.22 ± 0.04 ; vertical complex : 0.06 ± 0.06 basal lobes : 0.58 ± 0.04 ; brachial lobe : 0.77 ± 0.06 ; pedal lobe : 1.04 ± 0.08 ; palliovisceral lobe : 0.86 ± 0.05). Incubation of intact brains with 1.5 mM glutamate or NMDA or the nitric oxide donor 2-(N,N-diethylamino)diazenolate-2-oxide caused a fivefold rise in the levels of cyclic GMP, indicating operation of the glutamate-nitric oxide-cyclic GMP signaling pathway. Immunohistochemical mapping of Sepia CNS showed specific localization of nitric oxide synthase-like and NMDAR2/3-like immunoreactivities in the lateroventral palliovisceral lobe, the visceral lobe, and the pallial and visceral nerves, as well as in the sphincters and wall of the Ink Sac.
