Annales de Paleontologie最新文献

The Aït Athmane section is located in the eastern part of the central High Atlas, about 20 km north of Errachidia. Its Toarcian series consists of silty marl and silty marly limestone. Its lower part, of early (Levisoni Zone?) to middle Toarcian (Bifrons and Gradata? Zones) age, is rich in brachiopods (rhynchonellides and terebratulides). Its upper part, of late Toarcian age, is rich in terebratulids. Among eighteen reported brachiopod taxa, six are new for the central High Atlas. Their specific assemblages and stratigraphic distributions are similar to those of the Toarcian brachiopods reported from several basins of northern and southern margins of the Tethys and the Subboreal domain, particularly of western France.

The lower Cenomanian strata from the Batna region (NE Algeria) constitute the richest and most diversified deposits in terms of macro-invertebrates, mainly dominated by bivalves both in terms of specimens and taxa. Among them, Crassatellidae are restricted to the lower Cenomanian stratigraphical levels. They are represented by the single species Crassatella baudeti. The species is easily distinguished by its flattened boat anchor shape and quite strong commarginal lamellae, and is very abundant. It is present in levels ranging from Sharpeiceras schlueteri Subzone to Cunningtoniceras inerme Zone. The species is, therefore, a good marker of the last levels of the lower Cenomanian and the beginning of the midlle Cenomanian. A precise palaeontological description and an environmental discussion were conducted. Thus, Cr. baudeti would be indicative of a shallow environment, with cold but calm waters, normal salinity and moderately soft substrate. Recorded exclusively from the Cenomanian of a few Tethys localities, the exclusive presence of Cr. baudeti reflects a specific thermal gradient and climatic zonation.

Ammonitoceras Dumas, 1876 is a genus of heteromorph ammonites characterized by the presence of a peculiar ontogenetic stage in its inner whorls: the Ammonitoceras stage. But in spite of its wide paleogeographic and biostratigraphic extension throughout the Aptian (Lower Cretaceous), this genus remains poorly known. In the present work we study specimens of Ammonitoceras from the lower Aptian Deshayesites multicostatus (Deshayesites deshayesi Zone) to Dufrenoyia furcata (Dufrenoyia furcata Zone) subzones of the Les Ferres Aptian Basin (southeastern France). The results are as follows: (1) representatives of Ammonitoceras from this area are regarded dimorphic with criocone macroconchs and ancylocone microconchs, (2) their ontogenetic sequence is described, (3) their intraspecific variability is significant and concerns the adult size and the duration of the ontogenetic stages, especially the Ammonitoceras stage, (4) two species are recognized: the earlier Ammonitoceras ucetiae Dumas, 1876, characterized by a brief Ammonitoceras stage on average, and the latter Ammonitoceras lahuseni (Sinzow, 1906), characterized by a longer Ammonitoceras stage on average. The sample of the Deshayesites grandis Subzone (Deshayesites deshayesi Zone) is composed of specimens too fragmentary to be identified at species level.

A new genus and species of anaxyelid wasp is described and figured from the mid-Cretaceous Burmese amber as Curvitexis kopylovi gen. et sp. nov. The placement of this new genus within the Anaxyelidae is corroborated by its wing venation and the configuration of its mesosoma. This new genus differs from all other Syntexinae from the mid-Cretaceous Burmese amber biota, inter alia, owing to its forewing with the vein 1Rs curved and longer than 1M, the crossvein 1r-rs absent, the vein 2Rs + M present; the hind wing with the abscissa 2M + Cu present, the vein m-cu absent, and the cell r closed. The recently described Paraxiphydria resinata Gao et al., 2022 is transferred to Anaxyelidae: Syntexinae, and the subfamily Paraxiphydriinae Gao et al., 2022 is synonymized under Syntexinae.

The metriorhynchids from the Jurassic of Normandy have been known since the 19th century. However, the remains studied until now have rarely been found in anatomical connection. The acquisition of specimen MPV 2010.3.610 that was found in the Callovian of Vaches-Noires cliffs by the Paleospace Museum in 2010, allowed the first description of the most complete Metriorhynchidae from this locality so far. The analysis of this Metriorhynchidae raises questions about the taxonomic value of several criteria currently used to distinguish between the different Callovian and Oxfordian species. The study of the cranial and postcranial elements shows that this specimen presents diagnostic criteria of different Metriorhynchidae such as the shape of the prefrontals, the mandible, the palato-maxillary suture, the atlas/axis, the cervical vertebrae as well as the extension of the jugal bone and the morphology of the teeth. A discussion highlights the limitations of the current classification of Metriorhynchidae.

Among the ammonite collection from the Neuquén and Mendoza provinces made by G. Bodenbender, stands Aspidoceras bodenbenderi Behrendsen. This rare aspidoceratid is assigned to the lower Alternans Zone because of the associated Parodontoceras calistoides (Behrendsen), and can be most likely attributed to the recently established genus Hypowaagenia Schweigert & Schlampp.

The Ouarsenis Massif belongs to the Algerian Tell domain, which is considered as the eastern part of the Maghrebian Tethys former margin. The Berriasian-Valanginian Oued Fodda Formation outcropping in the Kef Aïn El Hadjela section, at the foot of the great peak of the Ouarsenis Massif, is composed of marls and laminated and bioturbated limestone alternations. The marl facies reveals diverse microfauna, including crinoids. These latter are represented by: Isocrinida [isocrinids Balanocrinus cf. gillieroni (de Loriol), Percevalicrinus aldingeri Klikushin, Isocrinus? lissajouxi (de Loriol)], Cyrtocrinida [cyrtocrinids (Phyllocrinus sp., Hemibrachiocrinus sp.)], and Roveacrinida gen. indet. sp. indet. [roveacrinids]. All these, with exception of roveacrinids and phyllocrinids, are noted for the first time from Algeria and African continent (southern margin of Tethys in the Maghreb). Knowledge on Cretaceous crinoids formerly described from Algeria is presented. It is also shown that crinoid assemblage and associated invertebrates are typical for relatively shallow, distal depositional setting situated below storm wave base.

Apart from the few works carried out in the North Tethyan basins, the palynological study of Mesozoic outcrops is still rare. Thus, the present study devoted to the Zahra Marls Formation (upper Bajocian) of the Rhar Roubane Mountains (northwestern Algeria), allowed us for the first time to inventory 44 different taxa. The palynological assemblages studied are strongly dominated by trilete spores (17 genera and 26 species), the most abundant of which are Concavissimisporites variverrucatus, Cyathidites australis and Cyathidites minor. Pollen grains are relatively frequent (10 genera and 16 species), while acritarchs and algae are represented by only two taxa (Micrhystridium sp. and Botryococcus sp.). In addition, the sporopollinic spectra dominated by the terrestrial elements are represented mainly by the spores of Pteridophyta and Bryophyta and gymnosperm pollen.

Ediacaran-Cambrian bioturbation on bedding planes provides physical and chemical data about the environmental conditions and biological activities of early metazoans. We propose a quantitative method to estimate horizontal disruption of the substrate using bedding-plane trace fossils from Brioverian deposits. This methodology provides the first quantitative analysis of the trace fossil assemblage from the Armorican Massif (Brittany, NW of France). The Ediacaran-Cambrian transition within the Brioverian series is characterized by the abundance of simple and horizontal trace fossils such as Helminthopsis, Helminthoidichnites, and Palaeophycus as well as rare Gordia and Spirodesmos. Recent U-Pb dating has been carried out on detrital zircon grains from the upper Brioverian series suggesting a late Ediacaran to Fortunian age of the fossiliferous deposits (ca. 550 to 530 Ma). With Arc-Gis software, we use a semi-quantitative approach to estimate the relative 2D bioturbation rate recorded on bedding planes. The dataset is used to discuss the feeding strategies and how the seafloor ecospace was colonized by the early bilaterian metazoans. This approach combines new values such as: the length of a trace fossil, the surface of a trace, the cumulative length, and the cumulative surfaces from all of the ichnofossils recorded on the same slate surface, to finally suggest that the bioturbation rate of the microbial grazers impacted the use of the seafloor ecospaces and feeding strategies through the biomats.

In the central High Atlas, the Toarcian Stage is represented by a marl and marly limestone series of variable thickness. Two sections have been studied: Amellago (500 m) and Aït Athmane (100 m). Ammonites from the two sections allowed to characterize the Polymorphum, Levisoni, Bifrons, Gradata, and Speciosum zones. The Polymorphum Zone provided, among others: Dactylioceras (Eodactylites) mirabile, D. (E.) pseudocommune, Dactylioceras (Orthodactylites) aff. crosbeyi and Neolioceratoides aff. hoffmanni; the Levisoni Zone provided a rich ammonite fauna composed of, Calliphylloceras nilssoni, Dactylioceras (Orthodactylites) cf. semiannulatum, Eleganticeras exaratum, Harpoceras falciferum, H. pseudoserpentinum, H. serpentinum, H. subplanatum, Hildaites cf. forte, H. levisoni, H. cf. serpentiniformis, H. cf. subserpentinus, H. striatus, H. wrighti, Lytoceras siemensi, Lytoceras sp., Maconiceras soloniacense, Phylloceras sp., Polyplectus pluricostatum et Polyplectus sp.; the Bifrons Zone provided Eleganticeras sp., Harpoceras subplanatum?, Hildoceras bifrons, H. lusitanicum, H. semipolitum, H. sublevisoni, Hildoceras sp., Porpoceras gr. vortex – verticosum; the Gradata Zone was characterized by Pseudocrassiceras bayani, P. frantzi, Pseudocrassiceras sp., Pseudocrassiceras sp. indet.; and the Speciosum Zone provided an Hammatoceras aff. insigne. These species have been described and illustrated for the first time for the central High Atlas. Most of them are common to several basins of the north Tethyan margin and the Subboreal Domain of NW Europe.