Abstract Orthoconic cephalopods are subordinate, but persistent, widespread and regionally abundant components of Triassic marine ecosystems. Here, we describe unpublished specimens from the Anisian (Middle Triassic) Besano Formation at Monte San Giorgio, Switzerland. They can be assigned to two major unrelated lineages, Coleoidea Orthoceratoidea. The orthoceratoids belong Trematoceras elegans (Münster, 1841) occur regularly within Formation, uniform in size, have few available morphological...

Abstract Coleoidea (squids and octopuses) comprise all crown group cephalopods except the Nautilida. Coleoids are characterized by internal shell (endocochleate), ink sac arm hooks, while nautilids lack an sac, suckers, have external conch (ectocochleate). Differentiating between straight conical conchs (orthocones) of Palaeozoic other ectocochleates is only possible when rostrum (shell covering chambered phragmocone) body chamber preserved. Here, we provide information on how this...

During the Palaeozoic, a diversification in modes of life occurred that included wide range predators.Major macroecological events include Cambrian Explosion (including Agronomic Substrate Revolution and here introduced 'Ediacaran-Cambrian Mouthpart Armament'), Great Ordovician Biodiversification Event, Palaeozoic Plankton Revolution, Siluro-Devonian Jaw Armament (newly herein) Devonian Nekton Revolution.Here, we discuss evolutionary advancement oral equipment, i.e. evolution mouthparts jaws...

Abstract Orthoceratoid cephalopods are common in the Palaeozoic rock record but became extinct Late Triassic. Many orthoceratoids contain cameral deposits, which enigmatic calcareous structures within their chambered shell that presumably balanced straight conchs a horizontal position. Since mid-19 th century, palaeontologists have attempted to understand deposit formation process. The various hypotheses include growth from fluids, precipitation by mantle or even dismissal as post-mortem...

Despite the excellent fossil record of cephalopods, their early evolution is poorly understood. Different, partly incompatible phylogenetic hypotheses have been proposed in past, which reflected individual author's opinions on importance certain characters but were not based thorough cladistic analyses. At same time, methods inference undergone substantial improvements. For datasets, typically only include morphological data, Bayesian and particular introduction fossilized birth-death model...

Abstract The fossilized birth–death (FBD) process provides an ideal model for inferring phylogenies from both extant and fossil taxa. Using this approach, fossils are directly integrated into the tree, leading to a statistically coherent prior on divergence times. Since typically not associated with molecular sequences, additional information is required place in tree. We use simulations evaluate two different approaches handling placement FBD analyses: using topological constraints, where...

The collection of cephalopods from eight sampling horizons within the Olenidsletta Member, Valhallfonna Formation, Floian–Dapingian, Profilstranda and nearby Profilbekken, Ny Friesland, Spitsbergen, resulted in detection 31 species, 20 genera, 12 families Ellesmerocerida, Endocerida, Riocerida, Dissidocerida, Orthocerida, Tarphycerida, Oncocerida. Of these, five genera (Ethanoceras gen. nov., Hinlopoceras Nyfrieslandoceras Olenidslettoceras Svalbardoceras nov.) 19 species (Bactroceras fluvii...

The Plectronoceratida includes the earliest known cephalopod fossils and is thus fundamental to a better understanding of origin early evolution this group molluscs. bulk described material comes from late Cambrian Fengshan Formation in North China with isolated occurrences South China, Laurentia, Kazakhstan Siberia. Knowledge their morphology taxonomy limited that most specimens were only studied as longitudinal sections, which are prone misinterpretations due variations plane section. We...

Abstract Throughout the Silurian and Devonian, cartilaginous fish successively evolved their specialized skeletal dental characteristics, increasingly refined sensory systems. The Late Devonian shark taxon Maghriboselache mohamezanei gen. et sp. n. from eastern Anti-Atlas of Morocco is known multiple specimens preserving most its features, which in some instances are preserved three dimensions. Key details dentition, jaws, pectoral skeleton shared with iconic genus Cladoselache ....

Devonian condensed sections of the northern Tafilalt Platform (Anti-Atlas, Morocco) are often extremely rich in cephalopod associations. Here, we describe Pragian to late Givetian cephalopods from Hamar Laghdad (Tafilalt). In total, found 44 species belonging 32 genera. While no new ammonoids or bactritids were recovered, report two genera and eight nautiloids, which have been studied much less than other groups past despite their great abundance, diversity morphologic disparity eastern...

In some Devonian strata in the eastern Anti-Atlas, fossil invertebrates are abundant, display a high taxonomic diversity and indicate many shifts palaeoecology. This is reflected changes faunal composition of vertebrates. Fossils jawed vertebrates late Lochkovian younger age have been recorded relatively common with their abundance increasing towards Late Devonian. Environmental also left mark preservation from which varies strongly through time regionally. variation partially reflects...

Fluctuations in body size of orthoconic cephalopods are reported from late Silurian to Late Devonian sediments at several locations the Tafilalt and Dra-Valley (Anti-Atlas, Morocco). The combination measurements diameters apical angles allows reconstruction their total conch (length volume), which revealed a strongly right-skewed distribution with an average length 278 mm, while largest actinocerids exceeded 2 m. Within examined groups (Actinocerida, Orthocerida, Pseudorthocerida), there is...

Belemnite rostra are very abundant in Mesozoic marine deposits many regions. Despite this abundance, soft-tissue specimens of belemnites informing about anatomy and proportions these coleoid cephalopods extremely rare limited to a few moderately large genera like Passaloteuthis Hibolithes. For all other genera, we can make inferences on their body as well mantle length by extrapolating from complete material. We collected data the hard parts some Jurassic order learn shared characteristics...

Nautilid, coleoid and ammonite cephalopods preserving jaws soft tissue remains are moderately common in the extremely fossiliferous Konservat-Lagerstätte of Hadjoula, Haqel Sahel Aalma region, Lebanon. We assume that hundreds cephalopod fossils from this region with soft-tissues lie collections worldwide. Here, we describe two specimens Syrionautilus libanoticus (Cymatoceratidae, Nautilida, Cephalopoda) Cenomanian Hadjoula. Both preserve parts, but only one shows an imprint conch. The...

1 Abstract The fossilized birth-death (FBD) process provides an ideal model for inferring phylogenies from both extant and fossil taxa. Using this approach, fossils (with or without character data) are directly considered as part of the tree. This leads to a statistically coherent prior on divergence times, where variance associated with node ages reflects uncertainty in placement taxa phylogeny. Since typically not molecular sequences, additional information is required place Previously,...

Although patchy, the fossil record of coleoids bears a wealth information on their soft part anatomy. Here, we describe remains axial nerve cord from both decabrachian (Acanthoteuthis, Belemnotheutis, Chondroteuthis) and octobrachian (Plesioteuthis, Proteroctopus, Vampyronassa) Jurassic. We discuss some hypotheses reflecting possible evolutionary drivers behind neuroanatomical differentiation coleoid arm crown. also propose potential links between habitat depth, mode life evolution...

cephalopods from Santa Rosita Formation in NW Argentina:

Abstract Tragoceras falcatum (S chlotheim , 1820) is a common, loosely coiled estonioceratid (Tarphycerida, Cephalopoda) occurring in the Kunda Regional Stage (early Darriwilian, Middle Ordovician) of Estonia. Although species quite well-known, we document some features for first time. For example, one specimen from Harku quarry (Estonia) with phosphatized replacement shell exhibits growth halts (megastriae) on body chamber. As they are not preserved smaller specimens, suggest that these...

The mudmound locality of Hamar Laghdad (Tafilalt Platform) contains possibly the greatest palaeobiodiversity, both horizontally in surrounding sediments and stratigraphically through Devonian sedimentary succession Moroccan eastern Anti-Atlas. From Ordovician to Devonian, region their fossil contents tend differ slightly from those time-equivalent strata other parts Tafilalt Platform. Our research provides a description sedimentological palaeontological record at covering Lochkovian Givetian...

Belemnites are an extinct group of Mesozoic coleoid cephalopods, common in Jurassic and Cretaceous marine sedimentary rocks.Despite their significance, total phylogeny has rarely been considered recent decades.In contrast, most researchers restricted the assignment families to one two usually recognized subgroups, Belemnitina Belemnopseina.As for many fossil have reluctant employ modern phylogenetic methods illuminate belemnites' evolutionary history.To overcome "dead end" belemnite...

Abstract. The biogenic carbonate hardparts of a large range marine organisms are the most important geochemical archives Earth’s climate dynamics through time and evolution life. That said, biomineralisation pathways, i.e., secretion mineral phases by organisms, complex may differ significantly between different taxa. In light this, it is critically to evaluate if related taxa might display similar hard parts geochemistry. If so, this relation bear information on evolutionary relationships...

Phylogenetic studies are rare in early Palaeozoic cephalopods. Here, we present the first cladistic analysis of order Lituitida based on published, as well some new, material. Three clades recovered within ingroup lituitids, Sinoceras, Ancistroceras and Lituites; former two groups correspond to family Sinoceratidae, latter one Lituitidae. The topology shows that Sinoceratidae represents basal branch, while Lituitidae a monophyletic, derived clade. Furthermore, describe new material four...