Biomarker records of late Neogene changes in northeast African vegetation

Geology ◽  
2005 ◽  
Vol 33 (12) ◽  
pp. 977 ◽  
Author(s):  
Sarah J. Feakins ◽  
Peter B. deMenocal ◽  
Timothy I. Eglinton
Keyword(s):  
Late Neogene

scholarly journals Geomorphological and Geochronological Analysis Applied to the Quaternary Landscape Evolution of the Yeltes River (Salamanca, Spain)

2020 ◽  
Vol 12 (19) ◽  
pp. 7869 ◽  
Author(s):  
Iván Martín-Martín ◽  
Pablo-Gabriel Silva ◽  
Antonio Martínez-Graña ◽  
Javier Elez
Keyword(s):  
Transfer Functions ◽  
Sedimentary Basins ◽  
Central Spain ◽  
Geomorphological Mapping ◽  
Fluvial Terraces ◽  
Digital Elevation ◽  
Late Neogene ◽  
Climate Evolution ◽  
Reported Data ◽  
Geomorphological Evolution

This paper aims to study the Quaternary geomorphological evolution of the Yeltes river-valley (Duero Basin, Central Spain) primarily based on the study of the Late Neogene piedmont dissected by the river and its Quaternary terrace sequence, since fluvial terraces are excellent archives to study the landscape and climate evolution during this period. Detailed geomorphological mapping implemented in GIS-based digital elevation models was used to the further applications of existing fluvial chronofunctions (relative terrace height-age transfer functions) to establish a numerical geochronology to the sequence of fluvial terraces in the zone. The obtained theoretical ages points to an onset of fluvial incision in the zone after 2.0–2.5 Myr ago, with the dissection of the “Raña surface” (a Gelasian alluvial piedmont widely developed in Central Spain). The obtained terrace ages coincide, in most cases, with warm isotopic stages (MIS) or mainly with the transit of cold to warm MIS. Additionally, this study suggests that the full connectivity of the Yeltes drainage (Ciudad Rodrigo Basin) with the Atlantic drainage was not completely effective until MIS 9 (c. 0.29 Myr). The new reported data allows for the exploration of the timing and processes involved in the capture of inland sedimentary basins (Ciudad Rodrigo, Duero basins) by the Atlantic drainage during the early Quaternary.

Selective extinction of late Neogene bivalves on the temperate Pacific coast of South America

Paleobiology ◽  
2007 ◽  
Vol 33 (3) ◽  
pp. 455-468 ◽  
Author(s):  
Marcelo M. Rivadeneira ◽  
Pablo A. Marquet
Keyword(s):  
Body Size ◽  
South America ◽  
Mass Extinction ◽  
Pacific Coast ◽  
Geographic Range ◽  
Life Habit ◽  
Late Neogene ◽  
Probability Of Extinction ◽  
Phylogenetic Effects ◽  
Selective Extinction

AbstractWe assessed selective extinction patterns in bivalves during a late Neogene mass extinction event observed along the temperate Pacific coast of South America. The analysis of 99 late Neogene and Quaternary fossil sites (recorded from 7°S to 55°S), yielding ∼2800 occurrences and 118 species, revealed an abrupt decline in Lyellian percentages during the late Neogene–Pleistocene, suggesting the existence of a mass extinction that decimated ∼66% of the original assemblage. Using the late Neogene data set (n = 59 species, 1346 occurrences), we tested whether the extinction was nonrandom according to taxonomic structure, life habit, geographic range, and body size. Our results showed that the number of higher taxa that went extinct was not different than expected by random. At first sight, extinction was selective only according to life habit and geographic range. Nevertheless, when phylogenetic effects were accounted for, body size also showed significant selectivity. In general, epifaunal, small-sized (after phylogenetic correction), and short-ranged species tended to have increased probability of extinction. This is verified by strong interactions between the variables herein analyzed, suggesting the existence of nonlinear effects on extinction chances. In the heavily decimated epifaunal forms, survival was not enhanced by widespread ranges or larger body sizes. Conversely, the widespread and large-sized infaunal forms tended to have lower probability of extinction. Overall, the ultimate extinction of late Neogene bivalve species along the Pacific coast of South America seems to have been determined by a complex interplay of ecological and historical (phylogenetic) effects.

scholarly journals Colouration, chaetotaxy and molecular data provide species-level resolution in a species complex of Dicranocentrus (Collembola : Entomobryidae)

2018 ◽  
Vol 32 (6) ◽  
pp. 1298 ◽  
Author(s):  
Feng Zhang ◽  
Daoyuan Yu ◽  
Mark I. Stevens ◽  
Yinhuan Ding
Keyword(s):  
Species Complex ◽  
Instar Larva ◽  
Molecular Data ◽  
Integrative Taxonomy ◽  
Species Level ◽  
Integrative Approach ◽  
Gene Markers ◽  
Late Neogene ◽  
Taxonomic Approach ◽  
Colour Patterns

Integrative taxonomic approaches are increasingly providing species-level resolution to ‘cryptic’ diversity. In the absence of an integrative taxonomic approach, formal species validation is often lacking because of inadequate morphological diagnoses. Colouration and chaetotaxy are the most commonly used characters in collembolan taxonomy but can cause confusion in species diagnoses because these characters often have large intraspecific variation. Here, we take an integrative approach to the genus Dicranocentrus in China where four species have been previously recognised, but several members of the genus have been morphologically grouped as a species complex based on having paired outer teeth on unguis and seven colour patterns. Molecular delimitations based on distance- and evolutionary models recovered four candidate lineages from three gene markers and revealed that speciation events likely occurred during the late Neogene (4–13million years ago). Comparison of intact dorsal chaetotaxy, whose homologies were erected on the basis of first instar larva, further validated these candidates as formal species: D. gaoligongensis, sp. nov., D. similis, sp. nov., D. pallidus, sp. nov. and D. varicolor, sp. nov., and increase the number of Dicranocentrus species from China to eight. Our study further highlights the importance of adequate taxonomy in linking morphological and molecular characters within integrative taxonomy.

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