Search results for "Ammonite"
showing 10 items of 96 documents
The space-time relationship of taxonomic diversity and morphological disparity in the Middle Jurassic ammonite radiation.
2007
14 pages; International audience; The Middle Jurassic ammonite radiation (from the late Aalenian to the end of the mid-Bathonian) is traced using combined analyses of morphological disparity and taxonomic diversity. The global signals of disparity and diversity are compared. These signals are then broken down by paleogeographical provinces to detect any heterogeneity in the radiation. An examination of the global signals reveals three biodiversity crises (discordances between signals) where morphological disparity grows while taxonomic diversity declines. The subdivision of the signals indicates the radiation was heterogeneous between provinces: the global signal is an aggregate of signals …
La faune ammonitique des marnes à fossiles ferrugineux de la région de Niort, France (Oxfordien inférieur, Zone à Cordatum, Sous-Zone à Cordatum)
2009
21 pages; Une nouvelle récolte d'ammonites dans les marnes à ammonites ferrugineuses de la région de Niort (France), autrefois étudiées par de GROSSOUVRE (1922), apporte de très nombreuses informations biostratigraphiques, paléoenvironnementales et paléobiogéographiques. La faune est datée de l'Oxfordien inférieur : Zone à Cordatum, Sous-Zone à Cordatum, partie inférieure probable. De plus, elle est unique en Europe occidentale 1) par les espèces trouvées -dont certaines ne semblent connues que dans ce gisement- 2) par la domination très atypique du binôme Taramelliceras - Creniceras qui représente les 2/3 des individus. Enfin, le spectre faunique plaide en faveur d'un milieu de plate-forme…
Carbon-isotope records of the Early Jurassic (Toarcian) Oceanix Anixic Event from the Valdorbia (Umbria-Marche Apennines) and Monte Mangart (Julian A…
2009
The Toarcian oceanic anoxic event (ca 183 Ma) coincides with a global perturbation marked by enhanced organic carbon burial and a general decrease in calcium carbonate production, probably triggered by changes in the composition of marine plankton and elevated carbon dioxide levels in the atmosphere. This study is based on high-resolution sampling of two stratigraphic successions, located in Valdorbia (Umbria-Marche Apennines) and Monte Mangart (Julian Alps), Italy, which represent expressions of the Toarcian oceanic anoxic event in deep-water pelagic sediments. These successions are characterized by the occurrence of black shales showing relatively low total organic carbon concentrations (…
Gauging scale effects and biogeographical signals in similarity distance decay analyses: an Early Jurassic ammonite case study.
2016
17 pages; International audience; In biogeography, the similarity distance decay (SDD) relationship refers to the decrease in compositional similarity between communities with geographical distance. Although representing one of the most widely used relationships in biogeography, a review of the literature reveals that: (1) SDD is influenced by both spatial extent and sample size; (2) the potential effect of the phylogenetic level has yet to be tested; (3) the effect of a marked biogeographical structuring upon SDD patterns is largely unknown; and (4) the SDD relationship is usually explored with modern, mainly terrestrial organisms, whereas fossil taxa are seldom used in that perspective. U…
Allometric space and allometric disparity: a developmental perspective in the macroevolutionary analysis of morphological disparity.
2008
8 pages; International audience; Here, we advance novel uses of allometric spaces--multidimensional spaces specifically defined by allometric coefficients--with the goal of investigating the focal role of development in shaping the evolution of morphological disparity. From their examination, operational measures of allometric disparity can be derived, complementing standard signals of morphological disparity through an intuitive and process-oriented refinement of established analytical protocols used in disparity studies. Allometric spaces thereby become a promising context to reveal different patterns of evolutionary developmental changes and to assess their relative prevalence and import…
Exploration of the Oxynoticeratidae ornamental morphospace using the discrete cosine transform (DCT) to analyze rib patterns.
2006
The discrete cosine transform (DCT) is a Fourier-related transform widely used in signal processing and well suited to analyzing open outlines such as ammonite ribs. The method is applied here to depict and decipher the ribbing morphospace of a large group of Lower Jurassic ammonites composed of the Oxynoticeratidae and their close ancestors. Because they are clearly associated with buoyancy and/or swimming ability, the usually clearly involute, comparatively smooth and compressed shells of these ammonites may well be misleading taxonomic markers. In this context, quantitative analysis of the ribbing pattern using the DCT may significantly improve our perception of the ornamental patterns e…
Nouveaux biohorizons et propositions pour le découpage biozonal ammonitique du Barrémien supérieur du Sud-Est de la France
2008
International audience; Un nouveau découpage biozonal ammonitique du Barrémien supérieur du Sud-Est de la France est proposé. Il tient compte des renouvellements fauniques, des données séquentielles ainsi que des données historiques. Il est enrichi de quatre biohorizons nouveaux. Le Barrémien supérieur comporte à présent les trois biozones (anciennement six) à Vandenheckei, Sartousiana et Giraudi. La première contient les trois sous-zones à Uhligi, dont le statut est discuté, Sayni et Barremense, ainsi que les deux nouveaux biohorizons à Marchandi et Breistrofferi (sommet de la Sous-Zone à Barremense). La Biozone à Sartousiana admet les sous-zones à Limentinus, Provincialis et Feraudianus. …
Qualitative-portable to quantitative-laboratory LIBS
2012
No abstract
The Global Boundary Stratotype Section and Point (GSSP) for the base of the Pliensbachian Stage (Lower Jurassic), Wine Haven, Yorkshire, UK
2006
14 pages; International audience; Following votes by the Pliensbachian Working Group, the Jurassic Subcommission and the International Commission on Stratigraphy, IUGS ratified the proposed Global Boundary Stratotype Section and Point (GSSP) for the base of the Pliensbachian Stage (Lower Jurassic) at the base of bed 73b in the Wine Haven section, Robin Hood's Bay, Yorkshire Coast, UK. This level contains the characteristic ammonite association Bifericeras donovani Dommergues and Meister and Apoderoceras sp. Complementary data include: a) Strontium-isotope stratigraphy, based on analysis of belemnites which yield a calcite 87Sr/86Sr ratio for the boundary level of 0.707425 and data supportin…
The Religion of Ammon
2015
The Ammonites, a people living east of the Jordan River, were neighbors of the ancient Israelites. The Old Testament (1 Kings, 11,5; 2 Kings, 23,13) and probably an inscription from the citadel of Amman mention Milkom as the supreme God of the Ammonites. Most Ammonite names did not contain the name of their national god, but used a more generic divine name, ’El. We don’t know if the name: ’El refers to the Canaanite god or to a local manifestation of this deity. Ammonites also worshiped other deities (i.e. ‘Astarte, ‘Anat, Ba‘al, Hadad/’Adad, Qos, Samas, YHWH and Yerah). A number of limestone statues and clay figurines of bearded individuals wearing an atef-crown could be Ammonite monarchs …