Добірка наукової літератури з теми "Coleoids"

AbstractFour rare Pennsylvanian (Stark Shale: Pennsylvanian, Missourian [=Kasimovian]) coleoids from Nebraska and Iowa, which are preserved as flattened partial phragmocones and body chambers associated with three-dimensionally fossilized ink sacs, are herein described as Pabianiconus starkensis new genus new species, Nebraskaconus whitei new genus new species, and Starkites compressus new genus new species. One specimen that is missing most of the phragmocone, is provisionally assigned to Donovaniconus. The fossils are assigned to the Coleoidea because of the presence of ink-filled sacs in the body chamber region of the conch. Additionally, eight fragmented and flattened phragmocones and body-chamber clusters with similar morphologies, including some with ink fragments and arm hooks, are assigned to the Coleoidea, but are not named because of their fragmentary condition. On most of the eight specimens, the shell material is associated with other unidentified finely macerated material, which suggests these fossils are probably either ejectoid masses or coprolites from coleoid predators and/or scavengers. However, the new genera named above appear to have been deposited as complete animals, based on the presence of the ink-filled sacs that are in the body chambers. With their body chamber and phragmocone morphologies, these rare coleoid taxa provide valuable information about conch variability within the Carboniferous evolutionary radiation of coleoids.

AbstractThe limited record of the bactritoid-like coleoid cephalopods is here expanded due to discovery of a late Carboniferous (Moscovian) orthocone comprising a phragmocone and a body chamber with a proostracum-like structure, a sheath-like rostrum, an ink sac, and a muscular mantle preserved on top of the conch. The specimen comes from the Wewoka Formation in the vicinity of the city of Okmulgee, Oklahoma, which previously yielded an orthocone indicative of an evolutionary branch of the Carboniferous cephalopods described as the order Donovaniconida Doguzhaeva, Mapes, and Mutvei, 2007a within the subclass Coleoidea Bather, 1888. Here, we describe from that site a bactritoid-like coleoid,Oklaconus okmulgeensisn. gen. n. sp. in Oklaconidae n. fam. A broad lateral lobe of the suture line and a compressed conch with a narrowed dorsal side and a broadly rounded ventral side distinguish this genus fromDonovaniconusDoguzhaeva, Mapes, and Mutvei, 2002b. The muscular mantle is preserved as a dense sheet-like structure, with a crisscross pattern and a globular-lamellar ultrastructure. Recent knowledge on the early to late Carboniferous coleoids is discussed. Carboniferous coleoids show a high morphological plasticity with a capacity for being altered to create the diverse combinations of ‘bactritoid’ and ‘coleoid’ structures. This could be the principle evolutionary driver of their radiation in the late Carboniferous.

Coleoid cephalopod molluscs comprise squid, cuttlefish and octopuses, and represent nearly the entire diversity of modern cephalopods. Sophisticated adaptations such as the use of colour for camouflage and communication, jet propulsion and the ink sac highlight the unique nature of the group. Despite these striking adaptations, there are clear parallels in ecology between coleoids and bony fishes. The coleoid fossil record is limited, however, hindering confident analysis of the tempo and pattern of their evolution. Here we use a molecular dataset (180 genes, approx. 36 000 amino acids) of 26 cephalopod species to explore the phylogeny and timing of cephalopod evolution. We show that crown cephalopods diverged in the Silurian–Devonian, while crown coleoids had origins in the latest Palaeozoic. While the deep-sea vampire squid and dumbo octopuses have ancient origins extending to the Early Mesozoic Era, 242 ± 38 Ma, incirrate octopuses and the decabrachian coleoids (10-armed squid) diversified in the Jurassic Period. These divergence estimates highlight the modern diversity of coleoid cephalopods emerging in the Mesozoic Marine Revolution, a period that also witnessed the radiation of most ray-finned fish groups in addition to several other marine vertebrates. This suggests that that the origin of modern cephalopod biodiversity was contingent on ecological competition with marine vertebrates.

The fossil record of gladius-bearing coleoids is scarce and based only on a few localities with geological horizons particularly favourable to their preservation (the so-called Konservat-Lagerstätten), which naturally leads to strongly limited data on geographical distributions. This emphasizes the importance of every new locality providing gladius-bearing coleoids. Here, we assess for the first time the gladius-bearing coleoid taxonomic diversity within the lower Toarcian “Schistes Cartons” of the Causses Basin (southeastern France). The material includes two fragmentary gladii, identified as Paraplesioteuthis sagittata and ?Loligosepia sp. indet. Just with these two specimens, two (Prototeuthina and Loligosepiina) of the three (Prototeuthina, Loligosepiina and Teudopseina) suborders of Mesozoic gladius-bearing coleoids are represented. Thus, our results hint at a rich early Toarcian gladius-bearing coleoid diversity in the Causses Basin and point out the need for further field investigations in the lower Toarcian “Schistes Cartons” in this area. This new record of Paraplesioteuthis sagittata is only the second one in Europe and the third in the world (western Canada, Germany and now France). Based on these occurrences, we tentatively suggest that P. sagittata originated in the Mediterranean domain and moved to the Arctic realm through the Viking Corridor to eventually move even farther to North America.

Abstract RNA editing by the ADAR enzymes converts selected adenosines into inosines, biological mimics for guanosines. By doing so, it alters protein-coding sequences, resulting in novel protein products that diversify the proteome beyond its genomic blueprint. Recoding is exceptionally abundant in the neural tissues of coleoid cephalopods (octopuses, squids, and cuttlefishes), with an over-representation of nonsynonymous edits suggesting positive selection. However, the extent to which proteome diversification by recoding provides an adaptive advantage is not known. It was recently suggested that the role of evolutionarily conserved edits is to compensate for harmful genomic substitutions, and that there is no added value in having an editable codon as compared with a restoration of the preferred genomic allele. Here, we show that this hypothesis fails to explain the evolutionary dynamics of recoding sites in coleoids. Instead, our results indicate that a large fraction of the shared, strongly recoded, sites in coleoids have been selected for proteome diversification, meaning that the fitness of an editable A is higher than an uneditable A or a genomically encoded G.

AbstractColeoid 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.

Because of physiology of coleoids, their fossils preserve soft-tissue-remains more often than other cephalopods. Sometimes, the phosphatized soft-tissues, particularly parts of the muscular mantle, display dark circular patterns. Here, we showcase that these patterns, here documented for fossil coleoids from the Jurassic of Germany and the Cretaceous of Lebanon, superficially resemble chromatophores (which enable living coleoids to alter their coloration). We examined and chemically analyzed the circular structures in these specimens, describe them, and discuss their genesis. Based on their structure and color, we visually differentiate between three types of circles. By comparison with similar structures, we suggest that these structures are not biogenic but Liesegang rings, which formed due to reaction-diffusion processes very soon after death.

Eight well-preserved cephalopod jaw fossils were discovered from the Upper Cretaceous (Santonian and Campanian) deposits of Vancouver Island, Canada, and Hokkaido, Japan. They occur individually in calcareous concretions and retain their three-dimensional architecture. Seven of them consist of a widely open outer lamella and a posteriorly projected inner lamella with a pointed rostrum. Both lamellae are made of fluorapatite, which may represent diagenetically altered chitin, and lack a calcareous element. Based on these diagnostic features, the seven jaw fossils are identified as lower jaws of the Coleoidea. Comparison with the lower jaws of modern coleoids allows us to distinguish the following new genera and species among them;Nanaimoteuthis jeletzkyiof the Order Vampyromorphida, andPaleocirroteuthis haggartiandP. pacificaof the Order Cirroctopodida. The lower jaws of these new taxa are clearly distinguished by having a much less projected inner lamella from those of modern and extinct species of the Superorder Decabrachia and the Order Octopodida. The maximum lengths of their outer lamellae (35.0-67.1 mm) are much larger than those of most modern vampyromorph and cirroctopodid species, indicating the large body size and weight of their owners. One of the other three lower jaws examined, characterized by a posteriorly extended outer lamella, may be assigned to the Octopodida. This study clearly demonstrates that large octobrachiate coleoids existed in the Late Cretaceous North Pacific.

AbstractGladius-bearing coleoids are rare in the fossil record. For the Cretaceous period, these cephalopods are mainly recorded in a few Lagerstätten in Lebanon (Haqel, Hajoula, En Nammoura, and Sahel Aalma). Here, we study 16 specimens of gladius-bearing coleoids from these Upper Cretaceous Lebanese Lagerstätten to investigate their taxonomic diversity. Besides two species that were already reported (Dorateuthis syriacaandGlyphiteuthis libanotica), one new species is identified in the Cenomanian site of Hajoula:Rachiteuthis acutalin. sp., as well as another form ofGlyphiteuthisfrom En Nammoura. Several studied specimens exhibit well-preserved soft-part characters. Among them, we document for the first time two transverse rows of sessile suckers inD.syriacaand we confirm the absence of tentacles, as well as the presence of a crop in this species. This strongly supports the phylogenetic proximity ofD.syriacawith modern vampyropods rather than with modern decabrachians. In turn, the similarity in gladius morphology between this taxon and modern squids is regarded as convergent.

Avec près de 800 espèces, les Coléoidés (seiches, calmars et poulpes) représentent 99% de la diversité des céphalopodes actuels. A cause de leur corps mou, peu propice à la fossilisation, les archives fossiles sont éparses et la connaissance de l’anatomie des taxons, fortement dépendante de la qualité de la préservation. La grande majorité des restes fossiles de coléoïdes sont en effet des parties rigides comme par exemple le gladius (comparable à la plume de calamar), et non les parties molles qui constituent pourtant la base des études portant sur l’actuel. De fait, l’écologie des taxons ainsi que les relations entre les groupes actuels fossiles restent difficiles à établir. En conséquence, déterminer une chronologie bien étayée de l'origine des clades modernes et des changements de niches écologiques reste un défi majeur pour reconstruire leur histoire évolutive. Dans ce contexte, l’étude de fossiles de coléoïdes provenant de gisements à conservation exceptionnelle où les parties molles sont fossilisées, à l’aide d’un panel de techniques d'imagerie non destructives haute résolution en constant développement, ouvre de nouvelles voies pour améliorer la résolution des données anatomiques et produire des avancées pour résoudre ces questions. Cette thèse a pour objectif d’exploiter ces techniques afin d’améliorer la systématique et la connaissance de l’écologie des coléoidés à des périodes clés de leur histoire évolutive. Elle se focalise sur les coléoïdés de deux Lagerstätten, dont les paléoenvironnements et la préservation sont contrastés, en utilisant une combinaison de techniques d'imagerie à haute résolution (µCTscan, XRF, RTI). Il s’agit de l’environnement bathyal de La Voulte-sur-Rhône (Callovien, France) dans lequel les fossiles sont préservés en 3D et des gisements d’environnements peu profond du Crétacé supérieur (Cénomanien et Santonien) du Liban ou les fossiles sont préservés en 2D dans des calcaires fins. La microtomographie à rayons X de plusieurs spécimens de V. rhodanica de La Voulte-sur-Rhône, a permis de réexaminer la morphologie externe et interne de cette espèce. Des comparaisons avec des taxons existants, y compris le seul membre de la famille existant, Vampyroteuthis infernalis, ont démontré que des caractères clés des Vampyroteuthidae, tels que le type d'attache de la ventouse, étaient présents dès le Jurassique. De plus, l’association de caractères de V. rhodanica indique un mode de vie prédateur pélagique, qui est totalement distinct de l’écologie de Vampyroteuthis. Un nouveau taxon, Vampyrofugiens atramentum a également été découvert. La présence d’une poche à encre et d’organes lumineux internes chez ce taxon représente une configuration inconnue chez d'autres taxons fossiles et questionne le mode de vie de cet organisme. Au sein des gisements Libanais, des analyses XRF, UV et RTI, et des mesures exhaustives sur 54 individus, la plus grande pour D. syriaca, a permis de réévaluer l'holotype et l'espèce, révéler de nouvelles informations systématiques et écologiques. Les variations morphologiques des gladius sont indépendantes des différents sites. Les résultats suggèrent une plus grande variabilité intraspécifique que celle supposée jusqu’alors et ouvre des questions sur la définition des caractères dans les analyses phylogénétiques. L’ensemble des résultats obtenus démontre que les coléoïdes ont atteint une grande diversité écologique dès le Jurassique et ont joué un rôle important dans les écosystèmes marins dès le Mésozoïque. Le niveau de détail anatomique observé (organisation anatomique musculaires des bras, éléments du système nerveux) ouvre de nouvelles perspectives pour les comparaisons entre actuel et fossile et promet une meilleure intégration de ce type de données dans les reconstructions phylogénétiques et paléoécologiques
Coleoids (cuttlefish, squid, and octopuses) represent 99% of the 800 species of modern cephalopods and play key roles in modern marine ecosystems. Their bodies are predominantly composed of soft tissues that rarely preserve in the fossil record. As such, the great majority of fossil coleoid remains are in fact rigid elements, such as the gladius (comparable to a squid pen), rather than the soft anatomical characters that form the basis of modern coleoid systematics. This means that the ecology of fossil taxa, and the relationships between fossil and modern clades remain unclear. In turn, determining proper dating of the origination of modern clades, and their shifts to paleo- and modern ecological niches, remains a major challenge for reconstructing their evolutionary history. In exceptional preservation deposits (Lagerstätten), coleoid soft parts do fossilize. The increasing capabilities of high-resolution, non-destructive imaging techniques (µCT, XRF, RTI), opens up new avenues for improving the resolution of anatomical data from these fossilized specimens, advancing our understanding around these questions. The aim of this thesis is to use these techniques to improve our knowledge of the systematics and ecology of coleoids at key periods in their evolutionary history. It focuses on coleoids from two sites with very different environments and preservation conditions: The Callovian-aged La Voulte-sur-Rhône (France), which represents a bathyal ecosystem where body fossils were preserved in 3D with pyrite and apatite, and the Upper Cretaceous (Cenomanian and Santonian) outcrops in Lebanon where coleoids were compressed within thin shallow marine limestone layers and their soft tissues were fossilized as 2D imprints. CT and Synchrotron X-ray microtomography analyses performed on multiple specimens of Vampyronassa rhodanica from La Voulte-sur-Rhône, allowed a re-examination of its external and internal morphology. Comparisons with other fossils and the extant relative Vampyroteuthis infernalis demonstrate that some key Vampyroteuthidae characters, such as its unique type of sucker attachment, were already present in the Jurassic. In addition, many characters in V. rhodanica indicate a pelagic predatory lifestyle, which is totally distinct from the deep-sea habitat of Vampyroteuthis. Investigation of the specimens assigned to V. rhodanica also led to the recognition of a new taxon, Vampyrofugiens atramentum. The presence of an ink sac and internal luminous organs in this new taxon is a pattern which is unknown in other fossil taxa, and raises questions about this organism's way of life. Dorateuthis syriaca, a key coleoid species from the Lebanese deposits, was re-appraised using a combination of high-resolution imaging techniques and comprehensive morphological measurements. This study was conducted on 54 individuals (including the holotype), making it the largest of its kind for D. syriaca. It allowed for a reappraisal of the species and holotype anatomy, and provided new systematic and ecological information. Morphological variations observed in the gladius were not determined to be site-dependent, rather suggest a greater intraspecific variability than previously assumed. This result raises questions about the definition of these characters in phylogenetic analyses. The overall results show that coleoids achieved a high level of ecological diversity as early as the Jurassic, and played an important role in marine ecosystems during the Mesozoic. The level of anatomical detail observed (muscular organization of the arms, elements of the nervous system) opens up new perspectives for comparisons between modern and fossil , and paves the way for better integration of this high resolution data into phylogenetic and paleoecological reconstructions

Although the fossil record of early cephalopods is rich and demonstrates the dominance of the group in Paleozoic times, the mainly soft-bodied coleoids (Cephalopoda: Coleoidea) are poorly represented. Therefore, little is known of the evolutionary history of coleoids through paleontology and current classifications of the subclass are based primarily on the morphology of extant representatives. A molecular phylogenetic analysis of the Coleoidea was therefore warranted. Phylogenetic relationships within the Coleoidea were constructed using molecular sequence data from one mitochondrial and two nuclear genes: cytochrome c oxidase I (COI) and two unlinked actin genes (Actin I and Actin II, respectively). A 657 base-pair portion of the COI gene was examined for 55 coleoid taxa encompassing a broad spectrum of diversity in the subclass. The COI gene exhibited the most rapid evolutionary rate among the three genes examined. Eighty-two sequences from a 784 base-pair portion of three paralogous actin genes were obtained from 44 terminal taxa. The Actin I gene was highly conserved and provided information for determining deep-level relationships. The Actin II gene was intermediately conserved and exhibited a broad range of sequence divergence than the COI and Actin I genes. The evolution of the actin gene family in cephalopods was compared to that in other molluscs, protostomes, and deuterostomes. Analyses of actin gene family evolution provided evidence that the Actin I gene encodes a muscle-type of actin, and that the Actin II gene encodes a cytoplasmic actin. These analyses also supported at least two independent derivations of muscle-type actins during the evolution of the protostome lineage. The following conclusions were drawn from the results of phylogenetic analyses: (1) the cephalopod subclass Coleoidea is monophyletic; (2) the order Octopoda is monophyletic and is sister group to the monotypic order Vampyromorpha; (3) the Decapodiformes, consisting of the orders Teuthoidea and Sepioidea, is monophyletic; (4) the orders Teuthoidea and Sepioidea are polyphyletic; (5) the teuthoid suborders Myopsida and Oegopsida are monophyletic and polyphyletic, respectively; (6) the Myopsida and the oegopsid families Chtenopterygidae and Bathyteuthidae are more closely related to the sepioid families Spirulidae, Sepiidae, and Sepiolidae, than they are to other teuthoid groups.

Abstract The class Cephalopoda is a monophyletic group which can be divided into two subclasses; Nautiloidea and Coleoidea. Nautiloidea contains the nautiluses (Nautilus and Allonautilus), whereas Coleoidea contains the octopuses (Fig. 1), squids, and cuttleAshes. Coleoid cephalopods diBer from nautiloids most notably through the reduction (or complete loss) and internalization of the shell. DeAning features of Coleoidea include a muscular mantle used for locomotion and respiration, the modiAcation of the foot into appendages around the mouth, a closed circulatory system, and complex eyes with lenses, although many of these features have been lost or reduced in various taxa. The widely cited annotated classification of the recent Cephalopoda (1) listed over 700 valid species in 139 genera and 47 families. Here we review the evolutionary relationships and divergence times of the members of the class Cephalopoda. Several alternative classifications have been proposed for relationships within Cephalopoda (2). Herein we follow the classification of Young et al. (3) that generally does not include ranks above the family level; however, we make certain assumptions about rank based on nomenclature and position.