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Petr Skupien - One of the best experts on this subject based on the ideXlab platform.
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current knowledge of Ammonite assemblages from the stramberk limestone tithonian lower berriasian at kotouc quarry outer western carpathians czech republic
Cretaceous Research, 2018Co-Authors: Zdeněk Vašíček, Petr Skupien, John W.m. JagtAbstract:Abstract Forty-two species of perisphinctoid Ammonites from the Stramberk Limestone at Kotouc Quarry near Stramberk (Moravia, Czech Republic) have been taxonomically assessed since 2013. Some of these species are contained in old collections at various Moravian-Silesian museums, while others are in the collections of two of us (ZV and PS); all are from Kotouc Quarry. In view of the fact that the Stramberk Limestone usually lacks distinct bedding, the stratigraphical position (Ammonite zones) of the taxa identified is derived from literature data. Ammonite species identified document the entire Tithonian to the lower Berriasian. One taxon of early Berriasian age is described as new, Neocosmoceras eliasi. The Tithonian Ammonite assemblage, with the exception of the uppermost portion of that stage, is close to those on record from the Mediterranean bioprovince in adjacent countries. In the uppermost Tithonian, a cosmopolitan species, Substeueroceras koeneni, appears. In the lower Berriasian, in addition to Mediterranean representatives, taxa that are known from the Crimean Peninsula and, exceptionally, those from the Subboreal Russian Platform Basin, are present.
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tithonian early berriasian perisphinctoid Ammonites from the stramberk limestone at kotouc quarry near stramberk outer western carpathians czech republic
Cretaceous Research, 2016Co-Authors: Zdeněk Vašíček, Petr SkupienAbstract:Abstract The present contribution deals with the taxonomy of 11 species of perisphinctoid Ammonite recovered recently from the Stramberk Limestone as exposed at the Kotouc Quarry (Stramberk, Moravia). The majority of these are described from this unit for the first time. In the stratigraphic evaluation, finds of Ammonites from other localities within the quarry, which were published by us in 2013 and 2014, are included. Ammonites recorded from beyond the continuous section document a stratigraphic range from upper lower Tithonian to lower Berriasian inclusive. In addition to taxonomy and new ontogenetic data of some species, we also present information on the distribution of species recognised and on their palaeogeographic distribution, as well as data on the structural composition of the Homole Block at Kotouc Quarry.
Zdeněk Vašíček - One of the best experts on this subject based on the ideXlab platform.
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current knowledge of Ammonite assemblages from the stramberk limestone tithonian lower berriasian at kotouc quarry outer western carpathians czech republic
Cretaceous Research, 2018Co-Authors: Zdeněk Vašíček, Petr Skupien, John W.m. JagtAbstract:Abstract Forty-two species of perisphinctoid Ammonites from the Stramberk Limestone at Kotouc Quarry near Stramberk (Moravia, Czech Republic) have been taxonomically assessed since 2013. Some of these species are contained in old collections at various Moravian-Silesian museums, while others are in the collections of two of us (ZV and PS); all are from Kotouc Quarry. In view of the fact that the Stramberk Limestone usually lacks distinct bedding, the stratigraphical position (Ammonite zones) of the taxa identified is derived from literature data. Ammonite species identified document the entire Tithonian to the lower Berriasian. One taxon of early Berriasian age is described as new, Neocosmoceras eliasi. The Tithonian Ammonite assemblage, with the exception of the uppermost portion of that stage, is close to those on record from the Mediterranean bioprovince in adjacent countries. In the uppermost Tithonian, a cosmopolitan species, Substeueroceras koeneni, appears. In the lower Berriasian, in addition to Mediterranean representatives, taxa that are known from the Crimean Peninsula and, exceptionally, those from the Subboreal Russian Platform Basin, are present.
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tithonian early berriasian perisphinctoid Ammonites from the stramberk limestone at kotouc quarry near stramberk outer western carpathians czech republic
Cretaceous Research, 2016Co-Authors: Zdeněk Vašíček, Petr SkupienAbstract:Abstract The present contribution deals with the taxonomy of 11 species of perisphinctoid Ammonite recovered recently from the Stramberk Limestone as exposed at the Kotouc Quarry (Stramberk, Moravia). The majority of these are described from this unit for the first time. In the stratigraphic evaluation, finds of Ammonites from other localities within the quarry, which were published by us in 2013 and 2014, are included. Ammonites recorded from beyond the continuous section document a stratigraphic range from upper lower Tithonian to lower Berriasian inclusive. In addition to taxonomy and new ontogenetic data of some species, we also present information on the distribution of species recognised and on their palaeogeographic distribution, as well as data on the structural composition of the Homole Block at Kotouc Quarry.
John W.m. Jagt - One of the best experts on this subject based on the ideXlab platform.
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current knowledge of Ammonite assemblages from the stramberk limestone tithonian lower berriasian at kotouc quarry outer western carpathians czech republic
Cretaceous Research, 2018Co-Authors: Zdeněk Vašíček, Petr Skupien, John W.m. JagtAbstract:Abstract Forty-two species of perisphinctoid Ammonites from the Stramberk Limestone at Kotouc Quarry near Stramberk (Moravia, Czech Republic) have been taxonomically assessed since 2013. Some of these species are contained in old collections at various Moravian-Silesian museums, while others are in the collections of two of us (ZV and PS); all are from Kotouc Quarry. In view of the fact that the Stramberk Limestone usually lacks distinct bedding, the stratigraphical position (Ammonite zones) of the taxa identified is derived from literature data. Ammonite species identified document the entire Tithonian to the lower Berriasian. One taxon of early Berriasian age is described as new, Neocosmoceras eliasi. The Tithonian Ammonite assemblage, with the exception of the uppermost portion of that stage, is close to those on record from the Mediterranean bioprovince in adjacent countries. In the uppermost Tithonian, a cosmopolitan species, Substeueroceras koeneni, appears. In the lower Berriasian, in addition to Mediterranean representatives, taxa that are known from the Crimean Peninsula and, exceptionally, those from the Subboreal Russian Platform Basin, are present.
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Ammonites on the brink of extinction diversity abundance and ecology of the order ammonoidea at the cretaceous paleogene k pg boundary
2015Co-Authors: Neil H Landman, John W.m. Jagt, Stijn Goolaerts, Elena A Jagtyazykova, Marcin MachalskiAbstract:We examined the stratigraphic distribution of Ammonites at a total of 29 sites around the world in the last 0.5 myr of the Maastrichtian. We demarcated this interval using biostratigraphy, magnetostratigraphy, cyclostratigraphy, and data on fossil occurrences in relation to the K/Pg boundary in sections without any facies change between the highest Ammonites and the K/Pg boundary. The Ammonites at this time represent all four Mesozoic suborders comprising six superfamilies, 31 (sub)genera, and 57 species. The distribution of Ammonites is dependent on the environmental setting. Recent data suggest that Ammonites persisted to the boundary and some species may have survived for several tens of thousands of years into the Paleogene. The best explanation for Ammonite extinction is a brief episode of ocean acidification immediately following the Chixculub impact, which caused the decimation of the calcareous plankton including the planktic post-hatching stages of Ammonites. The geographic distribution of Ammonites may also have played a role in the events with more broadly distributed genera being more resistant to extinction.
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Ammonite extinction and nautilid survival at the end of the cretaceous
Geology, 2014Co-Authors: Neil H Landman, Marcin Machalski, John W.m. Jagt, Stijn Goolaerts, Elena A Jagtyazykova, Margaret M YacobucciAbstract:One of the puzzles about the end-Cretaceous extinctions is why some organisms disappeared and others survived. A notable example is the differential extinction of Ammonites and survival of nautilids, the two groups of co-occurring, externally shelled cephalopods at the end of the Cretaceous. To investigate the role of geographic distribution in explaining this outcome, we compiled a database of all the occurrences of Ammonites and the nautilid genus Eutrephoceras in the last 0.5 m.y. of the Maastrichtian. We also included recently published data on Ammonite genera that appear to have briefly survived into the Paleocene. Using two metrics to evaluate the geographic range of each genus (first, a convex hull encompassing all of the occurrences of each genus, and second, the maximum distance between occurrences for each genus), we documented that most Ammonite genera at the end of the Maastrichtian were restricted in their geographic distribution, possibly making them more vulnerable to extinction. The geographic distribution of those genera that may have briefly survived into the Paleocene is significantly greater than that of non-surviving genera, implying that more broadly distributed genera were more resistant to extinction. This pattern is further emphasized by the broad distribution of Eutrephoceras , which matches that of the most widely distributed Ammonites at the end of the Maastrichtian. However, even the most widely distributed Ammonites eventually succumbed to extinction, whereas Eutrephoceras survived. Evidently, a broad geographic distribution may have initially protected some Ammonites against extinction, but it did not guarantee their survival.
Neil H Landman - One of the best experts on this subject based on the ideXlab platform.
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new evidence from exceptionally well preserved specimens sheds light on the structure of the Ammonite brachial crown
Scientific Reports, 2021Co-Authors: C P A Smith, Neil H Landman, Jeremie Bardin, Isabelle KrutaAbstract:Ammonite soft body remains are rarely preserved. One of the biggest enigmas is the morphology of the Ammonite brachial crown that has, up till now, never been recovered. Recently, mysterious hook-like structures have been reported in multiple specimens of Scaphitidae, a large family of heteromorph Late Cretaceous Ammonites. A previous examination of these structures revealed that they belong to the Ammonites. Their nature, however, remained elusive. Here, we exploit tomographic data to study their arrangement in space in order to clarify this matter. After using topological data analyses and comparing their morphology, number, and distribution to other known cephalopod structures, in both extant and extinct taxa, we conclude that these hook-like structures represent part of the brachial crown armature. Therefore, it appears that there are at least three independent evolutionary origins of hooks: in belemnoids, oegospids, and now in Ammonites. Finally, we propose for the first time a hypothetical reconstruction of an Ammonite brachial crown.
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ion microprobe measured stable isotope evidence for Ammonite habitat and life mode during early ontogeny
Paleobiology, 2018Co-Authors: Benjamin J Linzmeier, Neil H Landman, Shanan E Peters, R Kozdon, Kouki Kitajima, John W ValleyAbstract:Ammonites have disparate adult morphologies indicative of diverse ecological niches, but Ammonite hatchlings are small (~1 mm diameter), which raises questions about the similarity of egg incubation and hatchling life mode in Ammonites. Modern Nautilus is sometimes used as a model organism for understanding Ammonites, but despite their outward similarities, the groups are only distantly related. Trends in Ammonite diversity and extinction vulnerability in the fossil record contrast starkly with those of nautilids, and embryonic shells from Late Cretaceous Ammonites are two orders of magnitude smaller than nautilid embryonic shells. To investigate possible environmental changes experienced by Ammonite hatchlings, we used secondary ion mass spectrometry to analyze the oxygen and carbon isotope composition of the embryonic shells and early postembryonic whorls of five juveniles of Hoploscaphites comprimus obtained from a single concretion in the Fox Hills Formation of South Dakota. Co-occurring bivalves and diagenetic calcite were also analyzed to provide a benthic baseline for comparison. The oxygen isotope ratios of embryonic shells are more like those of benthic bivalves, suggesting that Ammonite eggs were laid on the bottom. Ammonite shell immediately after hatching has more negative δ18O, suggesting movement to more shallow water that is potentially warmer and/or fresher. After approximately one whorl of postembryonic growth, the values of δ18O become more positive in three of the five individuals, suggesting that these animals transitioned to a more demersal mode of life. Two other individuals transition to even lower δ18O values that could suggest movement to nearshore brackish water. These data suggest that Ammonites, like many modern coleoids, may have spawned at different times of the year. Because scaphites were one of the short-term Cretaceous–Paleogene extinction survivors, it is possible that this characteristic allowed them to develop a broader geographic range and, consequently, a greater resistance to extinction.
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upper maastrichtian Ammonite biostratigraphy of the gulf coastal plain mississippi embayment southern usa
Cretaceous Research, 2016Co-Authors: Ekaterina Larina, Neil H Landman, Matthew P Garb, Natalie R Dastas, Nicolas Thibault, Lucy E Edwards, George E Phillips, Remy RovelliAbstract:Abstract The Cretaceous outcrop belt of the Mississippi Embayment in the Gulf Coastal Plain (GCP) spans the Cretaceous/Paleogene (K/Pg) boundary. A detailed reconstruction of this time interval is critical for understanding the nature of biotic and environmental changes preceding the end-Cretaceous Mass Extinction event and for deciphering the likely extinction mechanism (i.e., bolide impact versus volcanism). Eight sections encompassing the K/Pg succession across the Mississippi Embayment were analyzed using biostratigraphic sampling of Ammonites, dinoflagellates, and nannofossils. An upper Maastrichtian Ammonite zonation is proposed as follows, from oldest to youngest: Discoscaphites conradi Zone, D. minardi Zone, and D. iris Zone. Our study documents that the Ammonite zonation established in the Atlantic Coastal Plain (ACP) extends to the GCP. This zonation is integrated with nannofossil and dinoflagellate biostratigraphy to provide a framework to more accurately determine the age relationships in this region. We demonstrate that Ammonites and dinoflagellates are more reliable stratigraphic indicators in this area than nannofossils because age-diagnostic nannofossils are not consistently present within the upper Maastrichtian in the GCP. This biostratigraphic framework has the potential to become a useful tool for correlation of strata both within the GCP and between the GCP, Western Interior, and ACP. The presence of the uppermost Maastrichtian Ammonite D. iris, calcareous nannofossil Micula prinsii, and dinoflagellates Palynodinium grallator and Disphaerogena carposphaeropsis suggests that the K/Pg succession in the GCP is nearly complete. Consequently, the GCP is an excellent setting for investigating fine scale temporal changes across the K/Pg boundary and ultimately elucidating the mechanisms causing extinction.
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3 d orientation and distribution of Ammonites in a concretion from the upper cretaceous pierre shale of montana
Swiss Journal of Palaeontology, 2015Co-Authors: Neil H Landman, Joyce C Grier, James W Grier, Kirk J Cochran, Susan M KlofakAbstract:One of the most common modes of preservation of Ammonites in the Upper Cretaceous US Western Interior is in concretions. We examine an accumulation of Ammonites from a single concretion in the lower Maastrichtian Pierre Shale of eastern Montana. The concretion is an oblate spheroid 50 cm in length and 26 cm in diameter, with its long axis parallel to the substrate. It contains approximately 90 Ammonite specimens representing three species of Hoploscaphites including adults and juveniles. The concretion also contains other fauna, primarily bivalves and gastropods. A total of 33 Ammonites, mostly adults, are concentrated in a cluster that spans 71 % of the length of the concretion (called the “sculpture”). 3-D measurements of the Ammonites in the sculpture reveal that (1) the shells dip at all angles, with a significant trend toward more horizontal from west to east; (2) the shells dip with a highly significant bias toward the east, suggesting a current from that direction; and (3) a highly significant number of the shells that are non-vertical face with their left side up. Most of the shells show lethal damage as indicated by missing pieces of body chamber. After settling to the bottom, the shells may have piled up against each other, creating a sediment trap. Other organisms such as scavenging gastropods may have been attracted to the site to feed on the stranded Ammonite carcasses. The chambers of the Ammonite phragmocones and even some of the body chambers are empty, suggesting relatively rapid burial. Oxygen and carbon isotopic analyses of the Ammonite shells reveal that they preserve their original isotopic signature. The values of δ13C of the carbonate cement in the concretionary matrix are much lighter than those in the Ammonite shells and imply that cementation of the concretion occurred in association with the decomposition of organic matter.
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Ammonites on the brink of extinction diversity abundance and ecology of the order ammonoidea at the cretaceous paleogene k pg boundary
2015Co-Authors: Neil H Landman, John W.m. Jagt, Stijn Goolaerts, Elena A Jagtyazykova, Marcin MachalskiAbstract:We examined the stratigraphic distribution of Ammonites at a total of 29 sites around the world in the last 0.5 myr of the Maastrichtian. We demarcated this interval using biostratigraphy, magnetostratigraphy, cyclostratigraphy, and data on fossil occurrences in relation to the K/Pg boundary in sections without any facies change between the highest Ammonites and the K/Pg boundary. The Ammonites at this time represent all four Mesozoic suborders comprising six superfamilies, 31 (sub)genera, and 57 species. The distribution of Ammonites is dependent on the environmental setting. Recent data suggest that Ammonites persisted to the boundary and some species may have survived for several tens of thousands of years into the Paleogene. The best explanation for Ammonite extinction is a brief episode of ocean acidification immediately following the Chixculub impact, which caused the decimation of the calcareous plankton including the planktic post-hatching stages of Ammonites. The geographic distribution of Ammonites may also have played a role in the events with more broadly distributed genera being more resistant to extinction.
Joseph L Kirschvink - One of the best experts on this subject based on the ideXlab platform.
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mid campanian lower maastrichtian magnetostratigraphy of the james ross basin antarctica chronostratigraphical implications
Basin Research, 2019Co-Authors: Florencia N Milanese, Joseph L Kirschvink, Eduardo B Olivero, Maria E Raffi, Pablo R Franceschinis, Leandro C Gallo, Steven M Skinner, Ross N Mitchell, Augusto E RapaliniAbstract:The James Ross Basin, in the northern Antarctic Peninsula, exposes which is probably the world thickest and most complete Late Cretaceous sedimentary succession of southern high latitudes. Despite its very good exposures and varied and abundant fossil fauna, precise chronological determination of its infill is still lacking. We report results from a magnetostratigraphic study on shelfal sedimentary rocks of the Marambio Group, southeastern James Ross Basin, Antarctica. The succession studied covers a ~1,200 m‐thick stratigraphic interval within the Hamilton Point, Sanctuary Cliffs and Karlsen Cliffs Members of the Snow Hill Island Formation, the Haslum Crag Formation, and the lower Lopez de Bertodano Formation. The basic chronological reference framework is given by Ammonite assemblages, which indicate a Late Campanian – Early Maastrichtian age for the studied units. Magnetostratigraphic samples were obtained from five partial sections located on James Ross and Snow Hill islands, the results from which agree partially with this previous biostratigraphical framework. Seven geomagnetic polarity reversals are identified in this work, allowing to identify the Chron C32/C33 boundary in Ammonite Assemblage 8‐1, confirming the Late Campanian age of the Hamilton Point Member. However, the identification of the Chron C32/C31 boundary in Ammonite Assemblage 8‐2 assigns the base of the Sanctuary Cliffs Member to the early Maastrichtian, which differs from the Late Campanian age previously assigned by Ammonite biostratigraphy. This magnetostratigraphy spans ~14 Ma of sedimentary succession and together with previous partial magnetostratigraphies on Early‐Mid Campanian and Middle Maastrichtian to Danian columns permits a complete and continuous record of the Late Cretaceous distal deposits of the James Ross Basin. This provides the required chronological resolution to solve the intra‐basin and global correlation problems of the Late Cretaceous in the Southern Hemisphere in general and in the Weddellian province in particular, given by endemism and diachronic extinctions on invertebrate fossils, including Ammonites. The new chronostratigraphic scheme allowed us to calculate sediment accumulation rates for almost the entire Late Cretaceous infill of the distal James Ross Basin (the Marambio Group), showing a monotonous accumulation for more than 8 Myr during the upper Campanian and a dramatic increase during the early Maastrichtian, controlled by tectonic and/or eustatic causes.
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molluscan biostratigraphy and paleomagnetism of campanian strata queen charlotte islands british columbia implications for pacific coast north america biochronology
Cretaceous Research, 2009Co-Authors: James W Haggart, Elizabeth S. Carter, Peter D Ward, Timothy D Raub, Joseph L KirschvinkAbstract:A previously uncollected fauna of Ammonites, bivalves, and other molluscs, associated with radiolarian microfossils, has been newly recognized near Lawn Hill on the east coast of central Queen Charlotte Islands, British Columbia. The regional biostratigraphic zonation indicates that the Lawn Hill fauna is correlative with the Nostoceras hornbyense zonule of the Pachydiscus suciaensis Ammonite biozone, recognized in the Nanaimo Group of southeast Vancouver Island. The Nostoceras hornbyense Zone (new) is herein proposed for strata of Pacific coast Canada containing the zonal index. Several molluscan taxa present in the Lawn Hill section are new to British Columbia and the Ammonite fauna suggests that the Nostoceras hornbyense Zone is late Campanian in age, supported by radiolarian taxa present in the section. Strata sampled in the Lawn Hill section preserve reversed-polarity magnetization, considered likely correlative with Chron 32r. The presence of the Nostoceras hornbyense Zone on Queen Charlotte Islands is the first recognition of this zone in Canada north of central Vancouver Island and represents the youngest Cretaceous known in this region. Campanian radiolarians identified from the Lawn Hill section are also the first recognized from the Pacific coast of Canada.
