The Cenomanian–Turonian boundary mass extinction (Late Cretaceous): Ammonoid biodiversity in the Eastern Desert, Egypt

2020 ◽  
Author(s):  
Ahmed Hefny ◽  
Gamal M. El Qot ◽  
Abd El Moneim El Araby ◽  
Mohamed F. Aly
Keyword(s):  
New Taxa ◽  
Mass Extinction ◽  
Benthic Fauna ◽  
Eastern Desert ◽  
Global Scale ◽  
Faunal Turnover ◽  
Time Period ◽  
First Occurrence ◽  
Faunal Diversity ◽  
Wadi Qena

<p>The Cenomanian-Turonian (C-T) mass extinction occurred during a peak global greenhouse interval, with eustatic sea-level elevated nearly 300 m above present stand. The time period spanning the Cenomanian–Turonian boundary was characterized by profound paleoenvironmental changes at global scale. World-wide consequences of these events have been the focus of new reports and their influence on local to regional depositional systems. A faunal turnover is recorded in the uppermost Cenomanian, marked by the disappearance of most of the Cenomanian taxa. The macrofossil contents of two Upper Cretaceous sections from Wadi Qena, central Eastern Desert, Egypt have been collected and studied in detail. These fossils, ranging in age from Late Cenomanian to middle Turonian. The Cenomanian- Turonian sequence of centeral Eastern Desert is represented by the fossiliferous Galala formation (about 90 meter) at base and Umm Omeiyid formation (about 40 meter) at top. The Galala Formation is characterized by shale, fossiliferous marl, marly limestone, sandstone and siltstone interbeds. The Umm Omeiyid Formation overlies the Galala Formation unconformably. It consists of unfossiliferous siltstone with fine, medium-grained hummocky cross-stratified sandstone intercalations with a few fossiliferous limestone beds and marl intercalations. The Cenomanian-Turonian boundary cuts within the upper part of the Galala Formation at the last occurrence (LO) of <em>Vascoceras cauvini</em> and the first occurrence (FO) of <em>Vascoceras proprium</em>. There is rapid faunal change across the Cenomanian-Turonian boundary in all the studied sections. Most benthic fauna become extinct at the Upper Cenomanian and new taxa appeared at the Lower Turonian. All Upper Cenomanian cephalopod taxa become extinct at the same level and new taxa appeared at the Lower Turonian. The faunal diversity decreased from the Upper Cenomanian to the Lower Turonian. The ammonite ranges are used for a biostratigraphic zonation of the Cenomanian- Turonian succession in the northern and central parts of Wadi Qena. five ammonite zones have been distinguished (<em>Neolobites vibrayeanus Zone , Vascoceras cauvini Zone , Vascoceras proprium Zone , Choffaticeras (Choffaticeras) segne Zone  and Coilopoceras requienianum Zone</em>).</p>

scholarly journals Hydrogeochemical characteristics and age dating of groundwater in the Quaternary and Nubian aquifer systems in Wadi Qena, Eastern Desert, Egypt

2015 ◽  
Vol 1 (3) ◽  
pp. 213-232 ◽  
Author(s):  
A. A. Abdel Moneim ◽  
E. M. Seleem ◽  
S. A. Zeid ◽  
S. G. Abdel Samie ◽  
Sameh Zaki ◽  
...  
Keyword(s):  
Eastern Desert ◽  
Age Dating ◽  
Aquifer Systems ◽  
Nubian Aquifer ◽  
Wadi Qena

scholarly journals Carbon monoxide (CO) and ethane (C<sub>2</sub>H<sub>6</sub>) trends from ground-based solar FTIR measurements at six European stations, comparison and sensitivity analysis with the EMEP model

2011 ◽  
Vol 11 (17) ◽  
pp. 9253-9269 ◽  
Author(s):  
J. Angelbratt ◽  
J. Mellqvist ◽  
D. Simpson ◽  
J. E. Jonson ◽  
T. Blumenstock ◽  
...  
Keyword(s):  
Transport Model ◽  
Global Scale ◽  
Global Model ◽  
Scale Model ◽  
Chemical Transport Model ◽  
Suitable Alternative ◽  
European Model ◽  
Time Period ◽  
Volatile Organic ◽  
Made In

Abstract. Trends in the CO andC2H6 partial columns ~0–15 km) have been estimated from four European ground-based solar FTIR (Fourier Transform InfraRed) stations for the 1996–2006 time period. The CO trends from the four stations Jungfraujoch, Zugspitze, Harestua and Kiruna have been estimated to −0.45 ± 0.16% yr−1, −1.00 ± 0.24% yr−1, −0.62 ± 0.19 % yr−1 and −0.61 ± 0.16% yr−1, respectively. The corresponding trends for C2H6 are −1.51 ± 0.23% yr−1, −2.11 ± 0.30% yr−1, −1.09 ± 0.25% yr−1 and −1.14 ± 0.18% yr−1. All trends are presented with their 2-σ confidence intervals. To find possible reasons for the CO trends, the global-scale EMEP MSC-W chemical transport model has been used in a series of sensitivity scenarios. It is shown that the trends are consistent with the combination of a 20% decrease in the anthropogenic CO emissions seen in Europe and North America during the 1996–2006 period and a 20% increase in the anthropogenic CO emissions in East Asia, during the same time period. The possible impacts of CH4 and biogenic volatile organic compounds (BVOCs) are also considered. The European and global-scale EMEP models have been evaluated against the measured CO and C2H6 partial columns from Jungfraujoch, Zugspitze, Bremen, Harestua, Kiruna and Ny-Ålesund. The European model reproduces, on average the measurements at the different sites fairly well and within 10–22% deviation for CO and 14–31% deviation for C2H6. Their seasonal amplitude is captured within 6–35% and 9–124% for CO and C2H6, respectively. However, 61–98% of the CO and C2H6 partial columns in the European model are shown to arise from the boundary conditions, making the global-scale model a more suitable alternative when modeling these two species. In the evaluation of the global model the average partial columns for 2006 are shown to be within 1–9% and 37–50% of the measurements for CO and C2H6, respectively. The global model sensitivity for assumptions made in this paper is also analyzed.

Biostratigraphy of the Lystrosaurus declivis Assemblage Zone (Beaufort Group, Karoo Supergroup), South Africa

2020 ◽  
Vol 123 (2) ◽  
pp. 207-216 ◽  
Author(s):  
J. Botha ◽  
R.M.H. Smith
Keyword(s):  
Mass Extinction ◽  
Closely Related Species ◽  
Community Assemblage ◽  
Faunal Assemblages ◽  
Karoo Basin ◽  
Time Period ◽  
Ecological Changes ◽  
Assemblage Zone ◽  
Permian Mass Extinction ◽  
Land Vertebrate

Abstract The earliest Triassic (Induan) Lystrosaurus Assemblage Zone has long been recognised as a particularly significant biozone in palaeoecological and palaeoenvironmental studies as it contains a community assemblage that records the survival and recovery from the end-Permian mass extinction (EPME). Here renamed the Lystrosaurus declivis Assemblage Zone it represents the best record globally of the ecological changes in terrestrial community structure and stability during this time period. The assemblage is dominated by two species of small to medium-sized herbivorous dicynodonts L. declivis and L. murrayi that co-occur in equal abundance, along with a range of smaller and less common faunivorous and insectivorous taxa. The latter comprise cynodonts (Thrinaxodon, Galesaurus, and Platycraniellus), therocephalians (Olivierosuchus, Regisaurus and Promoschorhynchus), the diminutive parareptiles (Saurodektes, Sauropareion, Colleta, Phonodus and Procolophon) and eureptilian arrivals possibly representing immigrant taxa (Prolacerta, Heleosuchus and Noteosuchus), among others. The attendant large carnivores were sabre-toothed Moschorhinus and the long-snouted archosauromorph Proterosuchus. In the aftermath of the mass extinction, new small temnospondyl taxa established their first occurrences i.e. Broomistega, Lydekkerina, and Micropholis, and have relatively high abundances compared to earlier temnospondyl records in the Karoo. Lithostratigraphically, the biozone for the most part spans the upper Palingkloof Member of the Balfour Formation and the overlying Katberg Formation in the western part of the basin, and the Normandien Formation in the east. The Lystrosaurus declivis Assemblage Zone of the main Karoo Basin hosts the type locality of the global Lootsbergian land-vertebrate faunachron. The biozone is one of the most widespread terrestrial faunal assemblages of western Gondwana with closely related species occurring in India and Antarctica. Similar, but much more distantly related taxa, occur in Induan-aged strata of Russia, China and Brazil.

Peaks from Random Data

1987 ◽  
Vol 1 (1) ◽  
pp. 65-68
Author(s):  
Sheldon M. Ross
Keyword(s):  
Mass Extinction ◽  
Continuous Distribution ◽  
Random Data ◽  
Time Period ◽  
Data Value

In an influential and controversial paper, Raup and Sepkoski [2] defined an event of mass extinction to have occurred in any time period (of roughly 6.4 million years) for which the data value for that time period (equal to the proportion of the families existing at the beginning of that period that went extinct during the period) exceeded that of its immediate neighbors. In this article we analyze the occurrence of such events when the data are randomly generated from a continuous distribution.

scholarly journals A new species of the deuterostome Herpetogaster from the early Cambrian Chengjiang biota of South China

2020 ◽  
Vol 107 (5) ◽  
Author(s):  
Xianfeng Yang ◽  
Julien Kimmig ◽  
Bruce S. Lieberman ◽  
Shanchi Peng
Keyword(s):  
New Species ◽  
The Body ◽  
Time Period ◽  
First Occurrence ◽  
Juvenile Specimen ◽  
History Of ◽  
Cambrian Radiation ◽  
Chengjiang Biota ◽  
A New Species ◽  
Number Of Branches

Abstract The Cambrian radiation represents a key time period in the history of life. Here, we add to the mounting evidence accumulating on the nature of deuterostomes from this time period through description of a new species of stalked deuterostome, Herpetogaster haiyanensis nov. sp., from the lower Cambrian (series 2, stage 3) Chengjiang biota of China. This represents the first occurrence of the genus in Gondwana, the first juvenile specimen, and the oldest specimens to date. Herpetogaster haiyanensis nov. sp. differs from H. collinsi Caron et al. (2010) in having a stolon that is separated into an outer and inner layer, the segmentation of the body and in the shape and number of branches of the tentacles. The new species reiterates earlier suggestions of deuterostome affinities of the genus―it appears closely related to Phlogites and then successively more distantly related to Cotyledon and Eldonia―and may have fed on hyolithids.

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