Search results for "Systematics"
showing 10 items of 6702 documents
Early–middle Jurassic lytoceratid ammonites with constrictions from Morocco: palaeobiogeographical and evolutionary implications.
2008
13 pages; International audience; The ammonite genus Alocolytoceras Hyatt, 1900 is an uncommon lytoceratid with distinctive shell ornament. A set of 58 specimens, recently collected at Amellago in the central High Atlas (Morocco), has enabled us to trace a succession of three species over eight biozones from the Toarcian to the Aalenian. Two specimens from the Lusitanian Basin are added for comparison. Following a review of the genus, based on original specimens and data from the literature, seven species are considered valid. A palaeobiogeographical synthesis of 13 regions demonstrates irregular distribution patterns over time, with a constant presence in the south-west Tethys and an insta…
New specimens of Lingulocystis Thoral, 1935 (Eocrinoidea, Blastozoa) from the Arenig (Lower Ordovician) of Montagne noire (southern France): Intraspe…
2007
16 pages; The genus Lingulocystis Thoral, 1935 is a preponderant component of the echinoderm fauna of the Lower Ordovician of Montagne noire (France), as suggested by its abundant remains. Its morphology is characterized by a flattened theca, composed of a frame enclosing numerous small polygonal central plates. The new specimens have been determined partly as Lingulocystis elongata Thoral, 1935 and partly as Lingulocystis aff. deani Ubaghs, 1994. This study is the first report of Lingulocystis in the Foulon Formation. New stratigraphic ranges have been defined for both species: L. elongata from the early Tremadoc (Saint- Chinian Formation) to the middle Arenig (lower part of the Landeyran …
The Pleistocene subterranean volesTerricola (Rodentia) of Serbia and Montenegro
2001
A general morphometrical analysis of the M1 was conducted to identify the subterranean vole species found in Upper Pleistocene localities from Serbia and Montenegro, and to clarify the systematic position and the phylogenetic relationships between the different species in the Balkans. From the different localities studied, we can assign one population toMicrotus (Terricola) thomasi and the others to theM. (T.) subterraneus group. This study suggests thatM. (T.) grafi can be considered as a chronological sub-species ofM. (T.) subterraneus or as a different but phylogenetically very close species.
New data on Marocella (Mollusca, Helcionelloida) from the Cambrian (Series 2–Miaolingian) of the Iberian Peninsula
2020
The present work is an overview of the current knowledge about the genus Marocella on the Iberian Peninsula, describing new specimens from the lower and middle Cambrian (Cambrian Series 2 and Miaol...
Names for trace fossils: a uniform approach.
2006
The taxonomic treatment of trace fossils needs a uniform approach, independent of the ethologic groups concerned. To this aim, trace fossils are rigorously defined with regard to biological taxa and physical sedimentary structures. Potential ichnotaxobases are evaluated, with morphology resulting as the most important criterion. For trace fossils related to bioerosion and herbivory, substrate plays a key role, as well as composition for coprolites. Size, producer, age, facies and preservation are rejected as ichnotaxobases. Separate names for undertracks and other poorly preserved material should gradually be replaced by ichnotaxa based on well-preserved specimens. Recent traces may be iden…
Description of two new fossil echinoids (Echinodermata: Echinoidea) from the Early Hauterivian (Early Cretaceous) of the Paris Basin (France)
2012
International audience; Deux nouveaux genres et espèces d'échinides, Salvaster roberti gen. et sp. nov. et Pygolampas edita gen. et sp. nov. provenant de la Formation des Calcaires à Spatangues (CSF) sont décrits. La CSF correspond à des sédiments calcaréo-argileux déposés dans le sud-est du bassin de Paris (France) à l'Hauterivien inférieur (Crétacé inférieur). Ces dépôts sont datés de la chronozone à Acanthodiscus radiatus, un intervalle de temps qui a correspondu à un haut niveau marin général en Europe de l'Ouest. La CSF a pourtant livré une riche faune fossile d'environnement marin peu profond, principalement représentée par des invertébrés benthiques. Parmi ceux-ci, 54 espèces d'échin…
Molecular markers and species delimitation: examples from the European batrachofauna
1996
AbstractMolecular techniques have revolutionised zoological systematics since the beginning of the seventies. Within the last twenty years numerous new amphibian species have been described in Europe almost solely on the basis of molecular data. This paper focuses on the use of molecular character state and genetic distance data for the delimitation of species. Case studies of European anurans (Discoglossus, water frogs of the genus Rana) are discussed in the framework of concurring species concepts to illustrate problems of assigning species status to divergent populations on the basis of molecular data.
Recommended minimal standards for describing new taxa of the family Halomonadaceae
2007
Following Recommendation 30b of the Bacteriological Code (1990 Revision), a proposal of minimal standards for describing new taxa within the family Halomonadaceae is presented. An effort has been made to evaluate as many different approaches as possible, not only the most conventional ones, to ensure that a rich polyphasic characterization is given. Comments are given on the advantages of each particular technique. The minimal standards are considered as guidelines for authors to prepare descriptions of novel taxa. The proposals presented here have been endorsed by the International Committee on Systematics of Prokaryotes Subcommittee on the Taxonomy of Halomonadaceae.
Evolutionary history of treecreeper vocalisations (Aves: Certhia)☆
2008
AbstractSince the vocalisations of passerine birds are in general a good means to separate taxa when external morphological differences are few, song and call recordings of 33 treecreeper (Certhia) taxa were sonagraphed and their parameters analysed. The vocalisations show low intra-individual and intra-population variation. Phylogenetic evolutionary units at the population level were delimited by time, frequency and syntax parameters by means of principal-component and discriminant analyses. Traits of territorial song were traced on a phylogenetic tree based on cytochrome b sequences, and a mean acoustic character difference was calculated. All presently recognised nine species could be di…
Antarctic hydroids (Cnidaria, Hydrozoa) of the families Campanulinidae, Lafoeidae and Campanulariidae from recent Antarctic expeditions with R.V.Pola…
2004
Species of the thecate hydroid families Campanulinidae, Campanulariidae and Lafoeidae have been studied. The material studied originates from the Weddell Sea and was collected by several French and German Antarctic expeditions with R.V. Polarstern. Fourteen species were found, three belonging to Campanulinidae, four to Campanulariidae and seven to Lafoeidae, one of these new to science (Filellum magnificum sp. nov.). The coppinia of Lafoea gaussica Vanhoffen, 1910, is described for the first time as well as the gonothecae of Opercularella belgicae (Hartlaub, 1904). A neotype is indicated for Filellum antarcticum (Hartlaub, 1904). Available data concerning autecology and geographical distrib…