scholarly journals New evidence on the origin of non-spinose pitted–cancellate species of the early Danian planktonic foraminifera

2013 ◽  
Vol 64 (3) ◽  
pp. 237-251 ◽  
Author(s):  
Ignacio Arenillas ◽  
Jose Antonio Arz
Keyword(s):  
Morphological Evolution ◽  
Planktonic Foraminifera ◽  
Middle Part ◽  
External Morphology ◽  
Evolutionary Trends ◽  
Test Size ◽  
Evolutionary Path ◽  
Origin And Evolution ◽  
Large Pore ◽  
New Evidence

Abstract Intermediate forms identified in some of the most continuous lower Danian sections allow a better understanding of the origin and evolution of pitted (Globanomalina) and cancellate (Praemurica) planktonic foraminifera. Both Globanomalina and Praemurica are part of a major Paleocene lineage, namely the “non-spinose lineage”, which started to diverge in the early Danian. Transitional specimens strongly suggest the evolution from Parvularugoglobigerina to Globanomalina, and then to Praemurica. These evolutionary turnovers were quite rapid (probably lasting less than 10 kyr), and seem to have begun in the time equivalent of the lower part of the E. simplicissima Subzone, namely the middle part of the standard Zone Pa. The initial evolutionary trends within this non-spinose lineage were the increase of test size and lip thickness, and the evolution from tiny pore-murals to large pore-pits, and from smooth to pitted and finally cancellate walls. Biostratigraphic data suggest that evolution of the wall texture preceded the morphological evolution within each genus. The oldest species of both Globanomalina and Praemurica, namely G. archeocompressa and Pr. taurica, initially retained the external morphology of the ancestral Parvularugoglobigerina eugubina. Since their divergence, Globanomalina and Praemurica followed a separate evolutionary path, evolving into morphologically different species.

scholarly journals Lithostratigraphy and microfacies analysis of Avanah Formation (Middle Eocene) in Gomaspan section northeast Erbil City, Kurdistan region, Iraq

2021 ◽  
Author(s):  
Irfan Sh. Asaad ◽  
Keyword(s):  
Middle Eocene ◽  
Planktonic Foraminifera ◽  
Middle Part ◽  
Petrographic Analysis ◽  
Microfacies Analysis ◽  
Dolomitic Limestone ◽  
Kurdistan Region ◽  
Thin Sections ◽  
Lithostratigraphic Units ◽  
Lagoon Environment

Lithostratigraphy and microfacies analysis of the Avanah Formation (Middle Eocene) were studied in the Gomaspan section in the Bina Bawi anticline, northeast of Erbil city, Kurdistan Region, Iraq. The field observations refer that the formation attains 56 m of medium to thick bedded yellow limestone, grey dolomitic limestone and blue marly dolomitic limestone interbedded with thin beds of blue marl and dark grey shale with an interval of sandy limestone in the middle part and thin to medium bedded limestone interbedded with red mudstone. The petrographic study of 29 thin sections of Avanah carbonates revealed that the majority of the matrix is carbonate mud (micrite) with few microspar. The skeletal grains include benthic foraminifera, dasycladacean green algae, ostracods, calcispheres, pelecypods, rare planktonic foraminifera and bryozoa in addition to bioclasts. Non-skeletal grains encompass peloids, oncoids, intraclasts and extraclasts with common monocrystalline quartz. Based on the field observation and petrographic analysis, three different lithostratigraphic units were identified. They are in ascending order: A-Thick bedded dolomitic marly limestone interbedded with shale. B- Bedded dolomitic limestone interbedded with shale and marl. C- Thin to medium bedded limestone interbedded with red mudstone. Depending on detailed microfacies analysis of carbonate rocks, three main microfacies and 12 submicrofacies are recognized. From the sum of all petrographic, facies, textural analyses, it is concluded that Avanah Formation in Gomaspan section, was deposited in shallow marine environment, semi restricted lagoon, in lower and upper parts and open lagoon environment in the middle part interval.

A Story of Us

2021 ◽  
Author(s):  
Lesley Newson ◽  
Peter Richerson
Keyword(s):  
Human Evolution ◽  
Cultural Evolution ◽  
Ice Age ◽  
Modern Humans ◽  
Evolutionary Path ◽  
Modern Times ◽  
Science Book ◽  
Early Humans ◽  
Last Ice Age ◽  
New Evidence

It’s time for a new story of our origins. One reason is that there a great deal of new evidence about what humans are like and the conditions that shaped human evolution. Another is that the thinking on human evolution has shifted. Evolutionists recognize that humans are very different from other animals, and they have been working to explain the different evolutionary path that humans took. There are still many gaps in the story, but this book describes seven points in our ancestors’ tale and explains the evidence behind these descriptions. The story begins seven million years ago, with the life of our ape ancestors, which were also the ancestors of today’s chimpanzees and bonobos. The second point is three million years ago with an ape that walked upright and lived outside the forest. Then follows a description of the life of early humans who lived one and a half million years ago. At the fourth point, 100,000 years ago, humans lived in Africa who were physically very similar to modern humans. The fifth is 30,000 years ago, during the last ice age, when our ancestors had evolved more complex cultures. The sixth is the period of accelerating cultural evolution that began as the planet started to recover from this ice age. Finally, beginning in the 1700s, there is the transformational period we are in now, which we call “modern times.” The style of this book is unusual for a science book because it has narrative sections that illustrate the lives of our ancestors and the problems they faced.

scholarly journals Origin and evolution of transporter substrate specificity within the NPF family

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Morten Egevang Jørgensen ◽  
Deyang Xu ◽  
Christoph Crocoll ◽  
Heidi Asschenfeldt Ernst ◽  
David Ramírez ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Biochemical Characterization ◽  
Biosynthetic Pathways ◽  
Cyanogenic Glucosides ◽  
Evolutionary Path ◽  
Substrate Specificities ◽  
Origin And Evolution ◽  
Glucosinolate Biosynthesis ◽  
Phylogenetic Lineage

Despite vast diversity in metabolites and the matching substrate specificity of their transporters, little is known about how evolution of transporter substrate specificities is linked to emergence of substrates via evolution of biosynthetic pathways. Transporter specificity towards the recently evolved glucosinolates characteristic of Brassicales is shown to evolve prior to emergence of glucosinolate biosynthesis. Furthermore, we show that glucosinolate transporters belonging to the ubiquitous NRT1/PTR FAMILY (NPF) likely evolved from transporters of the ancestral cyanogenic glucosides found across more than 2500 species outside of the Brassicales. Biochemical characterization of orthologs along the phylogenetic lineage from cassava to A. thaliana, suggests that alterations in the electrogenicity of the transporters accompanied changes in substrate specificity. Linking the evolutionary path of transporter substrate specificities to that of the biosynthetic pathways, exemplify how transporter substrate specificities originate and evolve as new biosynthesis pathways emerge.

scholarly journals Test-Size Evolution of the planktonic Foraminifera <i>Globorotalia menardii</i> in the Eastern Tropical Atlantic since the Late Miocene

2021 ◽  
Author(s):  
Thore Friesenhagen
Keyword(s):  
Atlantic Ocean ◽  
Planktonic Foraminifera ◽  
Early Pleistocene ◽  
Tropical Atlantic ◽  
Test Size ◽  
Tropical Atlantic Ocean ◽  
Size Evolution ◽  
Evolutionary Event ◽  
The Indian Ocean ◽  
Coiling Direction

Abstract. The mean test size of planktonic foraminifera (PF) is known to have increased especially during the last 12 Ma, probably in terms of an adaptive response to an intensification of the surface-water stratification. On geologically short timescales, the test size in PF is related to environmental conditions. In an optimal species-specific environment, individuals exhibit a greater maximum and average test size, while the size decreases the more unfavourable the environment becomes. An interesting case was observed in the late Neogene and Quaternary size evolution of Globorotalia menardii, which seems to be too extreme to be only explained by changes in environmental conditions. In the western tropical Atlantic Ocean (WTAO) and the Caribbean Sea, the test size more than doubles from 2.6 Ma to 1.95 Ma and 1.7 Ma, respectively, following an almost uninterrupted and successive phase of test size decrease from 4 Ma. Two hypotheses have been suggested to explain the sudden occurrence of a giant G. menardii form: it was triggered by either (1) a punctuated, regional evolutionary event or (2) the immigration of specimens from the Indian Ocean via the Agulhas Leakage. Morphometric measurements of tests from sediment samples of the Ocean Drilling Program (ODP) Leg 108 Hole 667A in the eastern tropical Atlantic Ocean (ETAO), show that the giant type already appears 0.1 Ma earlier at this location than in the WTAO, which indicates that the extreme size increase in the early Pleistocene was a tropical-Atlantic-Ocean-wide event. A coinciding change in the predominant coiling direction suggests that probably a new morphotype occurred. If the giant size and the uniform change in the predominant coiling direction are an indicator for this new type, the form already occurred in the eastern tropical Pacific Ocean at the Pliocene/Pleistocene boundary at 2.58 Ma. This finding supports the Agulhas Leakage hypothesis. However, the hypothesis of a regional, punctuated evolutionary event cannot be dismissed due to missing data from the Indian Ocean. This paper presents the AMOC/thermocline hypothesis, which not only suggests an alternative explanation for the sudden test-size increase in the early Pleistocene, but also for the test size evolution within the whole tropical Atlantic Ocean and the Caribbean Sea for the last 8 Ma. The test-size evolution shows a similar trend with indicators for changes in the Atlantic Meridional Overturning Circulation (AMOC) strength. The mechanism behind that might be that changes in the AMOC strength have a major influence on the thermal stratification of the upper water column, which is known to be the habitat of G. menardii.

Evolutionary ecology of Early Paleocene planktonic foraminifera: size, depth habitat and symbiosis

Paleobiology ◽  
2012 ◽  
Vol 38 (3) ◽  
pp. 374-390 ◽  
Author(s):  
Heather S. Birch ◽  
Helen K. Coxall ◽  
Paul N. Pearson
Keyword(s):  
Evolutionary Ecology ◽  
Dissolved Inorganic Carbon ◽  
Planktonic Foraminifera ◽  
Deep Ocean ◽  
Test Size ◽  
Early Paleocene ◽  
Ocean Carbon ◽  
Reconstructed Surface ◽  
Mass Extinction Event ◽  
The Impact

The carbon stable isotope (δ13C) composition of the calcitic tests of planktonic foraminifera has an important role as a geochemical tracer of ocean carbon system changes associated with the Cretaceous/Paleogene (K/Pg) mass extinction event and its aftermath. Questions remain, however, about the extent of δ13C isotopic disequilibrium effects and the impact of depth habitat evolution on test calcite δ13C among rapidly evolving Paleocene species, and the influence this has on reconstructed surface-to-deep ocean dissolved inorganic carbon (DIC) gradients. A synthesis of new and existing multispecies data, on the relationship between δ13C and δ18O and test size, sheds light on these issues. Results suggest that early Paleocene species quickly radiated into a range of depths habitats in a thermally stratified water column. Negative δ18O gradients with increasing test size in some species ofPraemuricasuggest either ontogenetic or ecotypic dependence on calcification temperature that may reflect depth/light controlled variability in symbiont photosynthetic activity. The pattern of positive δ13C test-size correlations allows us to (1) identify metabolic disequilibrium δ13C effects in small foraminifera tests, as occur in the immediate aftermath of the K/Pg event, (2) constrain the timing of evolution of foraminiferal photosymbiosis to 63.5 Ma, ∼0.9 Myr earlier than previously suggested, and (3) identify the apparent loss of symbiosis in a late-ranging morphotype ofPraemurica. These findings have implications for interpreting δ13C DIC gradients at a resolution appropriate for incoming highly resolved K/Pg core records.

The anatomy and seed plant affinities ofRhacopterisandSpathulopterisfoliage from the Dinantian (Lower Carboniferous) of Scotland

1997 ◽  
Vol 88 (4) ◽  
pp. 197-208 ◽  
Author(s):  
Jean Galtier ◽  
Brigitte Meyer-Berthaud ◽  
Rachel Brown
Keyword(s):  
External Morphology ◽  
Seed Plant ◽  
Lower Carboniferous ◽  
Anatomical Information ◽  
New Evidence

AbstractPermineralised material ofRhacopteris lindseaeformis(Bunbury) Kidston andSpathulopteris obovata(Lindley & Hutton) Kidston, showing both external morphology and excellent anatomical preservation, is described from the Lower Carboniferous (?Asbian, Upper Viséan) tuffs and dolomitic ashes outcropping at Weaklaw–Gullane, East Lothian, Scotland. These specimens provide the first anatomical information on these two well-known plant compression genera. The rachises haveLyginorachis-type anatomy with distinctive characters in the two species.Spathulopterisrachises correspond toLyginorachis kingswoodenseMeyer-Berthaud, previously described from the localities of Kingswood and East Kirkton, whereasRhacopterisshows similarities with the petiole attributed toBiligneafrom Oxroad Bay. Both foliage types conform to seed-fern frond organisation. This new evidence contradicts previous interpretations ofRhacopterisas a fern or a progymnosperm. We suggest thatRhacopteris lindseaeformisandSpathulopteris obovatarepresent the foliage of some of the arborescent gymnosperms which are found associated in several contemporaneous localities.

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