Search results for "tit"
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The stable isotope composition of organic and inorganic fossils in lake sediment records: current understanding, challenges, and future directions
2018
This paper provides an overview of stable isotope analysis (H, C, N, O, Si) of the macro- and microscopic remains from aquatic organisms found in lake sediment records and their application in (palaeo)environmental science. Aquatic organisms, including diatoms, macrophytes, invertebrates, and fish, can produce sufficiently robust remains that preserve well as fossils and can be identified in lake sediment records. Stable isotope analyses of these remains can then provide valuable insights into habitat-specific biogeochemistry, feeding ecology, but also on climatic and hydrological changes in and around lakes. Since these analyses focus on the remains of known and identified organisms, they …
The influence of religious identity and socio-economic status on diet over time, an example from medieval France
2019
International audience; In Southern France as in other parts of Europe, significant changes occurred in settlement patterns between the end of Antiquity and the beginning of the Middle Ages. Small communities gathered to form, by the tenth century, villages organized around a church. This development was the result of a new social and agrarian organization. Its impact on lifestyles and, more precisely, on diet is still poorly understood. The analysis of carbon and nitrogen isotopes in bone collagen from the inhabitants of the well-preserved medieval rural site Missignac-Saint Gilles le Vieux (fifth to thirteenth centuries, Gard, France) provides insight into their dietary practices and enab…
Why should traceology learn from dental microwear, and vice-versa?
2019
Dental and artifact microwear analyses have a lot in common regarding the questions they address, their developmental history and their issues. However, few paleontologists and archeologists are aware of this, and even those who are, do not take into account most of the methodological insights from the other field. In this focus article, we briefly review the main developmental steps of both methods, highlight how similar their histories are and how combining methodological developments can improve both research fields. In both cases, the traditional analyses have been strongly criticized mainly because of their subjectivity and their lack of repeatability and reproducibility. Quantitative …
Ammonoids and quantitative biochronology - A unitary association perspective
2015
Ammonoid evolutionary changes have long been recognized to be excellent time markers. They are the major macrofossil group to date and correlate Paleozoic and Mesozoic marine strata. Originations and extinctions of ammonoid species are commonly used to define GSSPs and build high resolution biozonations. Biochronology is now an advanced field with the recent development of computerized, quantitative methods yielding robust biochronological schemes. It has been demonstrated that such quantitative biochronological methods are very efficient to resolve (often complex) biostratigraphic contradictions and produce accurate and high resolution biozonations, thus enabling precise dating and correla…
Marine Early Triassic Actinopterygii from Elko County (Nevada, USA): implications for the Smithian equatorial vertebrate eclipse
2017
AbstractThe Early Triassic vertebrate record from low paleolatitudes is spotty, which led to the notion of an ‘equatorial vertebrate eclipse’ during the Smithian. Here we present articulated ray-finned fishes (Actinopterygii), collected from the marine Lower Triassic Thaynes Group at three new localities in Elko County (Nevada, USA), which were deposited within the equatorial zone. From the Smithian of the Winecup Ranch, we describe two partial skulls of the predatory actinopterygianBirgeria(Birgeriidae), attributed toB.americananew species andBirgeriasp.Birgeria americanan. sp. is distinguished from other species by a less reduced operculogular series. With an estimated total length of 1.7…
Transient metazoan reefs in the aftermath of the end-Permian mass extinction
2011
5 pages; International audience; Recovery from the devastating Permian-Triassic mass extinction about 252 million years ago is usually assumed to have spanned the entire 5 million years of the Early Triassic epoch1,2. The post-crisis interval was characterized by large-scale fluctuations of the global carbon cycle and harsh marine conditions, including a combination of ocean acidification, euxinia, and fluctuating productivity3. During this interval, metazoan-dominated reefs are thought to have been replaced by microbial deposits that are considered the hallmark of the Early Triassic4-7. Here we use field and microscopic investigations to document Early Triassic bioaccumulations and reefs f…
Permian-Triassic extinctions and rediversifications.
2015
Ammonoids were a major component of Permian marine faunas, but were on the verge of extinction during the Permian-Triassic crisis ~ 252 myr ago. Despite the severity of this extinction, their recovery was explosive in less than 1.5 myr. By Smithian time, they had already reached levels of taxonomic richness much higher than those of the Permian. The causes for the rapid Early Triassic diversification and proliferation of these organisms still remain elusive, but the evolution of their spatio-temporal diversity and disparity patterns closely correlates with the numerous environmental changes recorded during this time interval.
Revision of the genus Anasibirites Mojsisovics (Ammonoidea): An iconic and cosmopolitan taxon of the late Smithian (Early Triassic) extinction
2016
34 pages; International audience; The family Prionitidae Hyatt represents a major component of ammonoid faunas during the Smithian (Early Triassic), and the genus Anasibirites Mojsisovics is the most emblematic taxon of this family. Its stratigraphical range is restricted to the beginning of the late Smithian (Wasatchites distractus Zone). The genus is also characterized by an unusual cosmopolitan distribution, thus contrasting with most earlier Smithian ammonoid distributions that were typically restricted by latitude. Because the late Smithian witnessed an extinction of the nekton (e.g. ammonoids, conodonts) whose amplitude is equal to or larger than that of the end-Permian crisis, the nu…
Trilobites from the Red Fauna (latest Emsian, Devonian) of Hamar Laghdad, Morocco and their biodiversity
2018
36 pages; International audience; Trilobites are widespread in Early Devonian deposits of north Gondwana; some of the most emblematic ones were collected from the famous latest Emsian (Early Devonian) mudmound locality Hamar Laghdad in south-eastern Morocco. This locality is famous for its trilobites, especially for the conspicuous red-coloured remains of phacopid trilobites with often greenish eyes. Here, we present a taxonomic revision of the previously described trilobites from the so-called Red Fauna of Hamar Laghdad. We introduce the new taxa Harpes hamarlaghdadensis n. sp. and Morocops davidbrutoni n. sp. Phacopids dominate the trilobite assemblage from the Red Cliff at Hamar Laghdad …
Terrestrial plants and marine algae from the Late Jurassic lithographic limestone of the Causse Méjean (Lozère, southern France)
2016
International audience; A new Late Jurassic flora was discovered in the fossiliferous lithographic limestone of the Causse Méjean, Lozère (southern France). It consists of the first Kimmeridgian/Tithonian plants from this area. Fossil plants are represented by megaremains preserved as impressions. This flora shows a co-occurrence of terrestrial plants and marine algae. The land plants include vegetative remains ascribed to bennettitaleans (Zamites Brongniart, 1828), conifers (Brachyphyllum Brongniart, 1828), and pteridosperms (Cycadopteris Zigno, 1853). Marine algae were ascribed to dasyclads (Goniolina D’Orbigny, 1850). Lithological and palaeontological features suggest preservation in a f…