Longibelus gen. nov., a new Cretaceous coleoid genus linking Belemnoidea and early Decabrachia (original) (raw)
Related papers
The first diplobelid coleoid from the Late Cretaceous (Turonian) of Hokkaido (Japan)
Paleontological research, 2010
Outcrops of the Turonian Saku Formation in the Obira region of Hokkaido (northern Japan) have yielded two breviconic phragmocones that represent a previously unknown species of Conoteuthis, a comparatively well known genus of diplobelid coleoids. The selected holotype of Conoteuthis hayakawai sp. nov. preserves a spherical protoconch that deviates slightly from the longitudinal axis of the phragmocone and is the first record of a protoconch in Conoteuthis. Conoteuthis hayakawai sp. nov. differs only slightly from the type species Conoteuthis dupiniana from the Hauterivian-Aptian of Europe and Conoteuthis azizi Fuchs et al. from the Cenomanian of southeastern India through its weakly developed dorsal saddles. Conoteuthis hayakawai sp. nov. is the youngest report as well as the first record of the Diplobelida from the Paleopacific. This new find considerably extends the stratigraphical and geographical occurrence of the Diplobelida. Phylogenetically, the genus Conoteuthis is considered to be an isolated group within the Diplobelida. With respect to the controversial origin of the Sepiida and Spirulida, morphological comparisons have shown that the genus Conoteuthis cannot be a potential stem-group of the Sepiida and/or Spirulida.
Palaeontology, 2012
Groenlandibelus rosenkrantzi from the Maastrichtian of Greenland has long been thought to constitute an early representative of spirulid coleoids. This study shows that this view must be reassessed, at least in part. A re-investigation of the types and of material recorded subsequently has revealed that none of these specimens is conspecific with the holotype of G. rosenkrantzi. Cyrtobelus birkelundae gen. nov, sp. nov. differs from the type of G. rosenkrantzi in having lower chambers and in lacking an apically elongated sheath. The longiconic phragmocone of G. rosenkrantzi has more features in common with the presumed spirulid genus Naefia. A specimen described in detail by J. A. Jeletzky in the mid 1960s as 'G. rosenkrantzi' is designated holotype of C. birkelundae sp. nov., which means that internal phragmocone features are still unknown in G. rosenkrantzi. Cyrtobelus hornbyense gen. nov, sp. nov. from the Campanian of western Canada constitutes the first record of early spirulids from the northeast Pacific, being based on seventeen extraordinarily well-preserved phragmocones. This species differs from C. birkelundae sp. nov. only in the width of the siphuncular tube. The presence of a caecum, a nacre-less conotheca that represents the continuation of the protoconch conotheca, conothecal flaps that anchor the mural parts of the septa, and a thin investmentlike sheath are characters shared only with Recent Spirula. In particular, the unusual protoconch architecture of Cyrtobelus gen. nov. challenges a phylogenetic origin within bactritoid-like coleoids.
Swiss Journal of Palaeontology, 2021
A newly collected specimen of the enigmatic coleoid genus Longibelus is recorded from lower Turonian strata along the River Shadrinka in Sakhalin (Russian Far East). To date, this is the first record of Late Cretaceous coleoid cephalopods from the island and, in fact, from the entire Pacific coast of the Russian Federation. Lithological characteristics, coupled with published geochemical analyses (δ 13 C and C org content), suggest the habitat of this coleoid taxon to have been the middle to outer (i.e. distal) shelf. Its provenance from the stratigraphical level that is known as the Scaphites Event, characterised by a mass occurrence of Scaphites and Yesoites , may be indicative of occasional or marginal overlap in ranges, rather than life in similar habitats. On the basis of lithological features and in view of the extremely rare occurrence of Longibelus in rich ammonite assemblages with clear ecological/bathymetric preferences, the natural habitat of Longibelus may have comprised...
Neues Jahrbuch f&# 252; r …, 2007
were previously the only two species of plesioteuthidid coleoids luiown from the Solnhofe n Plattenkalks . Based on morphological comparisons of 154 specimens from the Solnhofen area, a thir d taxon must be considered as valid: Plesioteuthis subovata (MONSTER, 1846) . Additionally, it turne d out that "Senefelderiteuthis Icaussi" is identical with Dorateuthis tricarinata (MONSTER, 1846) . The stratigraphical range of the genus Dorateuthis can now be extended from the Late Cretaceou s to the Late Jurassic . Despite a remarkable similarity between prototeuthid and teuthid gladii, Prototeuthidids are attributed to the Vampyropoda . Unambiguous characters of teuthid Decabrachia such as a ventrolateral pair of elongated tentacles are unknown from the fossil record . Instead, characters such as interbrachial web, radial suckers and cirri rather indicate a closer relationship with th e Vampyropoda .
Late Cretaceous octobrachiate coleoid lower jaws from the north Pacific regions
Journal of Paleontology, 2008
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 ex...
Journal of Paleontology, 2010
The ontogeny of Belosaepia ungula Gabb, 1860 from the Crockett Formation (Bartonian stage, Eocene) of Texas is documented for growth from embryo to old age. During the last stage of life, much skeletal resorption occurred, resulting in a major change in form of the skeleton. The animal produced a large skeleton (to 180 mm in length and 50 mm in diameter) with endogastric coiling, oblique septa and a very large siphuncle. The skeleton has a guard with a solid posterior prong, a posteroventral corona plate and a noded dorsal shield. The ventral margin of the skeleton consists of a thin flattened deck containing strongly recurved septa, conotheca and a secondary prismatic shell layer. New terms are defined for features of the skeleton not previously described. The microstructure of the ventral deck and the presence of a rod structure between the prong and callus are described for the first time. Chamberlets similar to those in living Sepia cuttlebones are present between closely spaced septa and they vary from walled units on lateral margins to pillar form in mid-ventor. The siphuncle is secondarily thickened within the dorsal interior, producing a siphuncle band. The skeleton was produced by a deep-bodied animal of demersal life habits. The species B. uncinata, B. harrisi and B. alabamensis voltzi proposed by Palmer (1937) are synonymised with B. ungula. The species B. veatchii and B. saccaria of Palmer (1937) are considered to be valid species, but B. alabamensis proposed by Palmer (1937) is synonymised with B. veatchii. Descriptions of belosaepiid species must be based only on specimens of adult size that have not been affected by resorption.
The belemnite family Holcobelidae GUSTOMESOV, 1977 is revised, based on ca. 200 rostra from recent fieldwork as well as historical museum collections. The studied specimens originate from various European localities and are dated from the Early Aalenian to the Early Bajocian (Middle Jurassic). Eight species of the genera Holcobelus STOLLEY, 1927 (including H. elmii n. sp.) and Calabribelus n. gen. (with type species C. pallinii) are described. The evolution of the morphological characters at the family level is outlined and compared with acrocoelitids (Belemnitina) and pachybelemnopseids (Pachybelemnopseina); the possible phylogenetic links between the Holcobelidae and the latter are discussed. The stratigraphic and palaeobiogeographic distribution of holcobelids is analysed in respect to morphological changes, leading to a hypothesis on different lifestyles among the investigated taxa. The peculiar distribution pattern of Holcobelidae represents a colonization event by belemnites i...
Lethaia, 2017
Here we report the discovery of an Early Carboniferous (Late Visean) 3D cephalopod beak displaying significant similarity to the lower beak of Recent coleoids. It was uncovered in a fragmentarily preserved, longiconic shell from the Moorefield Formation in Arkansas, USA. This shell comprises a fractured 29-mm-long body chamber having a maximum diameter of~14 mm and showing an indistinct pro-ostracum-like structure. The beak-bearing shell could easily have been mistaken for a bactritid or orthocerid if it were not for a coleoid-type, weakly mineralized, evidently organic-rich shell wall which shows a lamello-columnar ultrastructure of a bulk of shell wall thickness and plate ultrastructure of thin outer layer. The specimen is assigned to an as-yet unnamed shelled coleoid of a so far unknown high-level taxonomic group. A partially exposed, 4.0-mm-long portion of the beak is the lower beak in oblique view from its left side. It exhibits fractured anthracite-like black, apparently originally chitin material, helmet-like general shape, broad hood with narrow shallow median groove and small notch posteriorly, pronounced pointed, non-biomineralized upside belt rostrum, high shoulder and about a 90-100 degrees jaw angle. A broad hood and massive rostrum emphasize its similarity to the lower mandible of Recent Vampyroteuthis and signify that its unique, among living coleoids, structure has been existed for at least since Late Visean time (~333 my). □ Arkansas, Cephalopoda, Coleoidea, Early Carboniferous, lower beak, shell wall ultrastructure, USA.