Jsowerbya, new genus of Muricidae (Mollusca: Gastropoda) from the Eocene of the Paris (France) and Hampshire (England) basins with a phylogenetic assessment of its Ocenebrine versus Ergalataxine affinities

Jsowerbya, nov. gen. (Gastropoda: Muricidae) includes three species from the Eocene of the Paris and Hampshire basins. It increases the number of extinct muricid genera, which curiously represent a very small fraction of the described genera. The species of Jsowerbya, often mistaken for the muricopsine genus Muricopsis, possess a unique combination of characters shared with the subfamilies Ocenebrinae and Ergalataxinae. A cladistic analysis, based on structural homologies of the spiral sculpture, however, suggests that Jsowerbya is closely related to the Ocenebrinae. Thus, Jsowerbya is here regarded as one the most basal Ocenebrinae.     

Non-marine Teredolites from the Middle Eocene of southern England

Middle Eocene, non-marine sediments from southern England contain examples of Teredolites borings in two contrasting palaeoenvironmental settings, viz.: (A) as in situ borings in an allochthonous lignite in an abandoned river channel and (B) as bored logs in cross-bedded fluvial sandstones of probable point-bar origin. The lignite is 0.30 m thick, of which the upper 0.20 m is intensely bored. Rounded pebbles of ?charcoal at its base also show small borings. A log in a fluvial sandstone shows densely-packed. radial club-shaped borings. now filled with sandstone. The wood substrate has subsequently been oxidized away. To our knowledge, this is the first detailed account of Teredolites from an ancient freshwater setting.     

Genome-wide CRISPR Screens Reveal Host Factors Critical for SARS-CoV-2 Infection

1. Download : Download high-res image (212KB)
2. Download : Download full-size image

     

Environmental margin and island evolution in Middle Eastern populations of the Egyptian fruit bat

Here, we present a study of the population genetic architecture and microevolution of the Egyptian fruit bat (Rousettus aegyptiacus) at the environmental margins in the Middle East using mitochondrial sequences and nuclear microsatellites. In contrast to the rather homogenous population structure typical of cave‐dwelling bats in climax tropical ecosystems, a relatively pronounced isolation by distance and population diversification was observed. The evolution of this pattern could be ascribed to the complicated demographic history at higher latitudes related to the range margin fragmentation and complex geomorphology of the studied area. Lineages from East Africa and Arabia show divergent positions. Within the northwestern unit, the most marked pattern of the microsatellite data set is connected with insularity, as demonstrated by the separate status of populations from Saharan oases and Cyprus. These demes also exhibit a reduction in genetic variability, which is presumably connected with founder effects, drift and other potential factors related to island evolution as site‐specific selection. Genetic clustering indicates a semipermeability of the desert barriers in the Sahara and Arabian Peninsula and a corridor role of the Nile Valley. The results emphasize the role of the island environment in restricting the gene flow in megabats, which is also corroborated by biogeographic patterns within the family, and suggests the possibility of nascent island speciation on Cyprus. Demographic analyses suggest that the colonization of the region was connected to the spread of agricultural plants; therefore, the peripatric processes described above might be because of or strengthened by anthropogenic changes in the environment.     

The first lithic industry of mainland Southeast Asia: Evidence of the earliest hominin in a tropical context

Recent discoveries of ancient sites in mainland Southeast Asia confirm the presence of old lithic industries as early as 0.8 Ma, i.e., at the transition between the Early to Middle Pleistocene. Although these open-air sites still require geochronological and biostratigraphic precisions, they allow us to understand the oldest vestiges of human presence in the tropics and the technical orientations chosen by these hominins. This article aims to present an objective and critical synthesis of the material discovered at the main sites. Some sites in Cambodia and Thailand have been the subject of archaeological field missions by the Ministère de l’Europe et des Affaires Étrangères (MEAE). The diversity of lithic tool types and manufacture methods encountered from the Middle Pleistocene in peninsular Asia shows a technical variability that stands out as a counterexample to diffusionist hypotheses of a cultural fabrication inherited from the West. The diversity of production methods, tools, and raw material matrices remains incomparable to those encountered in the West, Africa, or South Asia. To date, only evidence from China has allowed us to put forward the hypothesis of a common technical basis that would have spread from its southern territories; however, this hypothesis is currently under debate. Researchers have proposed the idea of continuous technical progress and the shift from heavy industry to a lighter and polished stone in Southeast Asia. However, the omnipresence of the pebble prevents a clear conclusion because these technical objects from Southeast Asia are quite simply incommensurable; a chopper in these regions may not be comparable with another chopper from the terraces of the Garonne or the Roussillon in France, for example. In other words, these tools are above all ‘tropical’ tools, and they belong to a distant cognitive world(s) with specific use(s), gesture(s), and meaning(s), making it impossible for them to be compared or evaluated by our faculty of Western judgment.     

Tropical niche conservatism as a historical narrative hypothesis for the Neotropics: a case study using the fly family Muscidae

Aim We evaluate the extent to which the tropical conservatism hypothesis can explain the evolutionary development of the Muscidae. Furthermore, we compare the geographical patterns of muscid phylogenetic structure with biogeographical regions that have been identified for Neotropical insects. Location Central and South America. Methods We modelled the geographic distributions of 658 species using Maxent and 19 environmental variables. A generic‐level supertree of the Muscidae was assembled using matrix representation with parsimony and used to map the geographic pattern of mean root distance (MRD), a metric of the relative evolutionary development of assemblages. Regression models (ordinary least squares and regression trees) were used to examine temperature and other environmental correlates of MRD to explore potential environmental drivers of muscid diversification. We used the regression tree results to recognize variable intervals that best explained MRD, and these intervals were mapped to recognize and compare with biogeographical regions of Neotropical insects. Results The geographic pattern of MRD was consistent with the tropical conservatism hypothesis: species in genera that diversified relatively early, as measured by their distance from the tree root, dominate lowland tropical South America, whereas species in genera that diversified more recently occupy extra‐tropical areas, sub‐Antarctic areas and the Andean highlands. Temperature was the strongest correlate of MRD. Three biogeographical regions were recognized and they coincided with two regions known for insects. Main conclusions Evolutionary responses of muscid flies to post‐Eocene climate change taking the form of an expansion of a tropical group into regions with colder climates may be fundamental to explaining their distribution in the Neotropics. Our biogeographical regions delimited by temperature and the phylogenetic metric, surrogates of the tropical conservatism hypothesis, were very similar to general insect patterns, supporting the ‘tropical origin and evolutionary response to climate cooling’ as a broadly based historical narrative for the Neotropics.     

Cultural conservatism and variability in the Acheulian sequence of Gesher Benot Ya‘aqov

The Acheulian Technocomplex exhibits two phenomena: variability and conservatism. Variability is expressed in the composition and frequencies of tool types, particularly in the varying frequencies of bifaces (handaxes and cleavers). Conservatism is expressed in the continuous presence of bifaces along an immense time trajectory. The site of Gesher Benot Ya‘aqov (GBY) offers a unique opportunity to study aspects of variability and conservatism as a result of its long cultural-stratigraphic sequence containing superimposed lithic assemblages. This study explores aspects of variability and conservatism within the Acheulian lithic assemblages of GBY, with emphasis placed on the bifacial tools. While variability has been studied through a comparison of typological frequencies in a series of assemblages from the site, evidence for conservatism was examined in the production modes expressed by the reduction sequence of the bifaces. We demonstrate that while pronounced typological variability is observed among the GBY assemblages, they were all manufactured by the same technology. The technology, size, and morphology of the bifaces throughout the entire stratigraphic sequence of GBY reflect the strong conservatism of their makers. We conclude that the biface frequency cannot be considered as a chrono/cultural marker that might otherwise allow us to distinguish between different phases within the Acheulian. The variability observed within the assemblages is explained as a result of different activities, tasks, and functions, which were carried out at specific localities along the shores of the paleo-Hula Lake in the early Middle Pleistocene.     

Giant lizards occupied herbivorous mammalian ecospace during the Paleogene greenhouse in Southeast Asia

Mammals dominate modern terrestrial herbivore ecosystems, whereas extant herbivorous reptiles are limited in diversity and body size. The evolution of reptile herbivory and its relationship to mammalian diversification is poorly understood with respect to climate and the roles of predation pressure and competition for food resources. Here, we describe a giant fossil acrodontan lizard recovered with a diverse mammal assemblage from the late middle Eocene Pondaung Formation of Myanmar, which provides a historical test of factors controlling body size in herbivorous squamates. We infer a predominately herbivorous feeding ecology for the new acrodontan based on dental anatomy, phylogenetic relationships and body size. Ranking body masses for Pondaung Formation vertebrates indicates that the lizard occupied a size niche among the larger herbivores and was larger than most carnivorous mammals. Paleotemperature estimates of Pondaung Formation environments based on the body size of the new lizard are approximately 2–5°C higher than modern. These results indicate that competitive exclusion and predation by mammals did not restrict body size evolution in these herbivorous squamates, and elevated temperatures relative to modern climates during the Paleogene greenhouse may have resulted in the evolution of gigantism through elevated poikilothermic metabolic rates and in response to increases in floral productivity.     

Taxonomic significance of short forms of middle Permian Pseudoalbaillella Holdsworth and Jones, 1980 (Follicucullidae,Radiolaria)

Middle Permian Pseudoalbaillella from the Xiaodong area in South China were studied using fossil morphology. Short forms of Pseudoalbaillella fusiformis (Holdsworth and Jones), Pseudoalbaillella internata Wang, and Pseudoalbaillella monacantha (Ishiga and Imoto), characterized by a short and skirt-like pseudoabdomen, were confirmed. We conclude that the short forms were derived from their respective species by breaking off during disruptive processes. If this is true, there may be structurally weakened parts in the pseudoabdomen.     

Lignites of Kutch,western India: Dinoflagellate biostratigraphy and palaeoclimate

The Eocene epoch in the Indian subcontinent was marked by widespread deposition of lignite and coal. While several of these deposits formed during the Early Eocene, corresponding to Early Eocene hyperthermal events, the lignites of Kutch in western India formed later during the Middle Eocene. An integrated biostratigraphy based on dinoflagellates and foraminifera assigns a Bartonian age to the succession, which likely corresponds to the time of the Middle Eocene warming. The spores, pollen, dinoflagellates and foraminifera suggest a restricted marine, near shore depositional environment adjacent to tropical rainforest. The lignites of Kutch suggest high precipitation during or just preceding the warm climate of the Middle Eocene.