Search results for "Conodont"
showing 10 items of 44 documents
Warming or cooling in the Pragian? Sedimentary record and petrophysical logs across the Lochkovian–Pragian boundary in the Spanish Central Pyrenees
2016
Abstract High-resolution petrophysical correlation methods were applied, for the first time, to mid-Paleozoic rocks of the Pyrenees. The methods included magnetic susceptibility measurements (MS), gamma-ray spectrometry (GRS), and alignment of MS logs using the dynamic time-warping (DTW) algorithm. Conodont biostratigraphy provided the basic framework necessary for work with the GRS and MS logs. Despite differences in the sediment patterns and accumulation/erosion rates, the logs from two selected sections in the Spanish Central Pyrenees show a striking symmetry that correlates well with the previously published logs from the Barrandian area in the Czech Republic. The high similarity betwee…
Tethyan magnetostratigraphy from Pizzo Mondello (Sicily) and correlation to the Late Triassic Newark astrochronological polarity time scale
2004
We present the magnetostratigraphy and stable isotope stratigraphy from an expanded (~430-m-thick) Upper Triassic marine limestone section at Pizzo Mondello, Sicily, and review published biostratigraphic information that can be used to defi ne the location of the conodont Carnian-Norian and Norian- Rhaetian boundaries in this section. Pizzo Mondello offers good potential for magnetostratigraphic correlation of marine biostratigraphic and chemostratigraphic data with the continental Newark astrochronological polarity time scale (APTS) for development of an integrated Late Triassic time scale. The relatively stable average values of 18O centered on 0‰ are a strong indication that the Cherty …
Microstructure of Triassic conodont Pseudofurnishius murcianus van den Boogaard: Functional implications
2020
Pseudofurnishius murcianus van den Boogaard is a Triassic conodont with a very characteristic morphology, a blade with a rostral platform heavily denticulated, that makes it easily distinguishable from other coeval species. It is a well-know taxon that has been the object of several palaeobiological works, focused on their apparatus reconstruction, ontogeny and, recently, their P 1 element function. In order to increase our palaeobiology knowledge of this taxon we undertook a histological analysis to corroborate the functional hypothesis established for this conodont. The histological study demonstrated the presence of different microstructural types, suggesting that they are functional ada…
Exploring the major depletions of conodont diversity during the Triassic
2014
International audience; In this paper, we show that the Triassic fossil record reflects just two great depletions of conodont diversity before the Rhaetian, which occurred in the Smithian (Olenekian, Early Triassic) and in the Julian (Carnian, Late Triassic). By exploring this context, our results highlighted that they respond to different origination?extinction dynamics. Thus, while the Smithian diversity depletion can be interpreted as a consequence of elevated extinction, the Julian diversity depletion was triggered by fluctuations in origination regime. This evidence suggests that, despite the role of extinction on diversity losses, conodonts suffered crucial changes on the origination …
There is no general model for occlusal kinematics in conodonts
2014
Knowledge of conodont element function is based largely on analysis of morphologically similar P-1 elements of few comparatively closely related species known from abundant articulated remains. From these, a stereotypical pattern of rotational occlusion has been inferred, leading to the suggestion that this may represent a general model for ozarkodinin P-1 elements at the very least. We test the generality of this occlusal model through functional analysis of Pseudofurnishius murcianus P-1 elements which, though superficially similar to homologous elements in gnathodids, evolved their platform morphology independently, through a different mode of morphogenesis, and in a different topologica…
X-ray nanotomography and electron backscatter diffraction demonstrate the crystalline, heterogeneous and impermeable nature of conodont white matter
2021
Conodont elements, microfossil remains of extinct primitive vertebrates, are commonly exploited as mineral archives of ocean chemistry, yielding fundamental insights into the palaeotemperature and chemical composition of past oceans. Geochemical assays have been traditionally focused on the so-called lamellar and white matter crown tissues; however, the porosity and crystallographic nature of the white matter and its inferred permeability are disputed, raising concerns over its suitability as a geochemical archive. Here, we constrain the characteristics of this tissue and address conflicting interpretations using ptychographic X-ray-computed tomography (PXCT), pore network analysis, synchro…
Conodonts versus Triassic Climatic and Eustatic Changes
2015
Kılıç, Ali Murat (Balikesir Author)
Ostracod and conodont faunal changes across the Frasnian-Famennian (Devonian) boundary at Els Castells, Spanish central Pyrenees
2008
Diverse conodont and silicified ostracod assemblages were found in the Spanish Pyrenees (Els Castells section), in the Frasnian/Famennian boundary beds (laterhenana and/orlinguiformis to latetriangularis zones), in strata below and above the well-known Kellwasser Extinction Event. Many of the ostracods studied here are conspicuous elements of the “Thuringian Mega-Assemblage”, and show maximum affinities with faunas from the southeastern Cantabrian Mountains (Spain), eastern Thuringia and the Harz (Germany). The composition of the faunas, however, is not uniform through the Els Castells section. A rather sharp break exists, roughly coinciding with the Frasnian/Famennian boundary. The break i…
Challenging Darwin: Evolution of Triassic Conodonts and Their Struggle for Life in a Changing World
2017
Abstract The phylogeny and distribution of Triassic conodonts reveal many aspects of their natural history. Conodonts incorporate the morphologic response to temperature as well as to eustatic cycles. Speciation, radiation, and extinction are not fortuitous and evolution uses heterochrony (progenesis and neoteny) in response to stress-generating events. Proteromorphosis (reappearance of ancestral morphs) and paedomorphosis (retention of juvenile traits) is a reaction to sublethal environmental stress. This often follows radiation of fully developed forms in the recovery stage after extinction that timely matches transgressions. Evolutionary retrogradation (neoteny) during eustatic high stan…
Conodont association of the Bashkirian-Moscovian boundary interval of the Donets Basin, Ukraine
2018
Ten sections spanning the Bashkirian-Moscovian boundary interval were studied in the Donets Basin. Six of them contain most representative conodont and foraminifer associations. In this paper we focused on three the most complete sections that include stratigraphically important conodont species, which belong to the Declinognathodus, Idiognathoides, Idiognathodus, Neognathodus, “Streptognathodus”, Mesogondolella and Diplognathodus genera. The majority of those species are widely distributed, which makes the correlation to other areas reliable. Two biotic events in conodont evolution were discovered in these sections. Two conodont lineages established here are considered as potential markers…