Palaeobiodiversity and Palaeoenvironments最新文献

During excavations at Koridornaya Cave (Pompeevskiy Ridge, Russian Far East) in 2017–2018 numerous skeletal elements of late Quaternary mammals were recovered for the first time in Priamurye. The aim of this work is to determine the shrew (Soricidae) species and to estimate their abundance. In the deposits of Koridornaya Cave, 890 cranial remains of shrews were found belonging to 10 species from genera: Sorex, Neomys, Beremendia, and Crocidura. The formation period of the deposits is determined as the Last Glacial Interstadial (MIS 3), and the upper part of the deposits contains also Holocene (MIS 1) components. The studied Late Pleistocene communities of shrews of the Pompeevskiy Ridge included modern inhabitants of this territory (S. caecutiens, S. isodon, S. unguiculatus, S. daphaenodon, S. roboratus, S. minutissimus, N. fodiens, and C. lasiura) and S. tundrensis; C. ex gr. suaveolens appeared in the Holocene. Sorex gracillimus, which currently lives here, was not recorded either because it was absent during the time of deposition of the fauna or it was extremely rare. Because of remaining uncertainties, within the framework of this study, B. minor is not considered a part of the Late Pleistocene fauna of Far Eastern shrews. The dominant species in the shrew communities in the Last Glacial Interstadial at the Pompeevskiy Ridge was S. caecutiens, just as in the shrew communities during Late Pleistocene to Holocene in the southern Sikhote-Alin Mountains and in most of modern shrew communities in the south of the Russian Far East.

Palynological investigation was conducted to reconstruct the palaeodepositional and palaeoclimatic conditions of the late Eocene Kopili Shale of Assam-Arakan Basin (AAB), India. The palynoassemblage (PA) comprises particulate organic matters (POMs), dinoflagellate cysts (DCs), pteridophytic spores (PSs), angiospermous pollen (APs), acritarchs, fungal remains (FRs) and foraminiferal linings (FLs). Amorphous organic matter (AOM), making up 55 to 97 % of the PA, is the predominant form of organic matter (OM) among the POMs. The palynoflora is dominated by DCs comprising 5 genera (Cordosphaeridium, Hystrichosphaeridium, Heteraulacacysta, Glaphyrocysta and Thalassiphora) and 22 referable species. The PSs are assigned to 3 families (Polypodiaceae, Matoniaceae and Osmundaceae) and 8 referable species. The APs are characterised by 3 families (Arecaceae, Fabaceae and Gunneraceae) and 9 pollen species. The palynological data reveal that the Kopili Shale was deposited in a marginal-marine to shallow marine environment under suboxic-anoxic basin condition having influx of coastal elements into the depositional basin. The palaeoclimatic condition during the deposition of the Kopili Shale was tropical-subtropical and warm-humid.

Three collections of clam shrimp from the Lower Devonian (upper lower Emsian) Klerf Formation of Willwerath and Waxweiler in the western Eifel Mountains are herein studied. Four discernible morphotypes are present in the Willwerath assemblage. These morphotypes correspond to the previously described species from this locality: Pseudestheria diensti (Gross), Pseudestheria subcircularis Raymond, and Palaeolimnadiopsis? eifelensis Raymond. The fourth morphotype also closely corresponds to Pseudestheria diensti, but is slightly different in outline. Asmussia willweratica (Novozhilov) is an objective synonym of Pseudestheria subcircularis. In the Willwerath clam shrimp sample, it is difficult to disentangle taphonomic/preservational versus ontogenetic/sexual variation. If taphonomic/preservational causes could be confirmed, all the Willwerath specimens may represent just one taxon and Pseudestheria subcircularis and Palaeolimnadiopsis? eifelensis would be potential subjective synonyms of Pseudestheria diensti. However, we refrain from a formal taxonomic act, which requires a larger number of specimens to be analysed.

In addition, we investigated two samples from Waxweiler, which originate from distinct centimetre-thick layers and therefore represent associations. One of these associations comprises two discernible clam shrimp morphotypes. Because of limited preservation of morphological characters, one is here left in open nomenclature as Spinicaudata incertae sedis, whereas the other is recognised as a new species of the family Palaeolimnadiopseidae, Palaeolimnadiopsis frankeorum sp. nov. The second association from Waxweiler comprises at least four, possibly six different clam shrimp taxa. In addition to Pseudestheria diensti, Palaeolimnadiopsis sp., and poorly preserved Asmussia- and Ulugkemia-like specimens, two taxa can be described as new, namely the vertexiid Cornia wasvilrensis sp. nov. and the leaiine Eicheleaia wenndorfi gen. nov. et sp. nov. Altogether, the Klerf Formation at Waxweiler yields a total of at least five (possibly eight) clam shrimp taxa. The palaeoenvironment of these early clam shrimp from the Klerf Formation is interpreted as a non-marine, relatively proximal deltaic setting with no or very minor marine influence, such as a deltaic freshwater pond or lake. The comparatively high diversity of these lower Devonian clam shrimp suggests a considerably earlier origin and cryptic evolution of the group.

Abstract

The Miocene succession (Allala River Sandstones and Tenes Blue Marls Formation) that crops out in the Tenes area, situated in the northeast of the Lower Chelif Basin in NW-Algeria, contains a low-diversity assemblage of trace fossils. Fifteen (15) ichnogenera were identified: Arenicolites, Beaconites, Cylindrichnus, Diplocraterion, Macaronichnus, Ophiomorpha, Palaeophycus, Parahaentzschelinia, Planolites, Rosselia, Skolithos, Taenidium, Teichichnus, Thalassinoides and Zoophycos. Ethologically, these ichnogenera chiefly display dwelling and feeding activities. The presence of thick, deep-tier, scattered, mainly vertical dwelling burrows attributed to the Skolithos ichnofacies indicates high energy conditions, normal oxygenation and soft substrate. Moreover, elements of the Cruziana ichnofacies show more varied behavioural strategies and higher inchnodiversity with the dominance of horizontal burrows of deposit-feeders. This ichnological study supports the palaeoenvironmental interpretation based on sedimentological analysis of a wave-dominated siliciclastic platform (backshore to offshore), allowing a more precise zonation of the shoreface zone (middle/upper and lower shoreface). In addition, this study allows evaluation of variable degrees of storm influence in response to the contrasting palaeogeomorphology of the coastline.

The Givetian Balduinstein Reef developed upon mixed felsic lavas and volcaniclastic tuffs. The Givetian age of the reef is proven by conodonts (Polygnathus rhenanus/varcus Zone to the Polygnathus ansatus Zone) and the occurrence of the brachiopod Stringocephalus burtini. Remains of land plants and subaerially ejected volcanic bombs in the vicinity of the outcrops document that the volcano was an emerged island surrounded by a fringing reef in an unstable tectonic environment. Reef development is characterised by a complex interaction of volcanism, erosion and the rate and pattern of sea-level change, which resulted in a variety of facies settings and rock-types. Microfacies analysis and rock-types prove that the fringing reef was backed by a shallow lagoon. A lime mudstone/alkali rhyolitic breccia represents a lava flow, or more probably a dome collapse breccia, which flowed into the lagoonal mud and confirms a contemporaneous occurrence of volcanism and reef growth. Reefs flourished during several episodes of inactivity of the volcano, particularly in the upper part of the sections, suggesting that the reef development kept up with sea-level changes and/or local events. Lithofacies of the upper part of the youngest section point to a regressive phase. The distinctive depositional architecture and evolution of the Balduinstein Reef are interpreted as having been controlled mainly by regional tectonics and volcanism with contributions from eustasy.

A new find of terrestrial plant Equisetites cf. lyellii is reported from the Early Cretaceous of Slovakia. It comes from the Mráznica Formation of the Rajec Basin in Fatricum, Zbyňov locality, Rajecké Teplice (Žilina district). The presence of a 53 mm long horsetail axis provides good evidence of terrestrial environments during sedimentation of the studied strata. According to our interpretation, such a plant strongly indicates a moist to wet habitat (even swampy environments) on the presumed dryland from where it was transported. This dryland could represent an isolated unknown small island(s) in the vicinity, or the Vindelician-Bohemian Massif that was active as a dryland for the entire period of time from the Triassic through the Late Cretaceous. However, the exact palaeogeographic position of the Fatricum during the Mesozoic in relation to the Vindelician Landmass is not entirely clear, and such an interpretation needs a bit of caution.

Benthic graptolites (Graptolithina) were surprisingly common and diverse in the Miaolingian (Cambrian), but have rarely been described in detail. Encrusting and erect growing colonies already evolved and can be differentiated in early Miaolingian faunas. The Rhabdopleuridae with their encrusting colonies provide few fossils, but members of the erect growing, bushy colonies of the Dithecodendridae are more common, at least as fragments indicating considerable fragmentation and transport. In the Wuliuan, the benthic graptolites reached a considerable diversity at the genus level with at least 6 genera appearing in this interval. The most common taxon is the encrusting genus Sphenoecium with its robust colonies, showing a worldwide distribution. Most taxa, however, are known from few records and their biostratigraphical and palaeogeographical distribution cannot be established yet. Erroneously, the widely distributed Tarnagraptus with its conical thecae has often been misidentified as the Ordovician Mastigograptus, but differs considerably in its tubarium construction and both might not be closely related.

The Marmoucha syncline is located in the eastern part of the Middle Atlas. In this syncline, the “Gypsum marls” (Bathonian-?Callovian) are covered by red detrital deposits which outcrop in Aït Bazza locality. The upper limit of these detrital deposits is below the transgressional unconformity of the Albian?-Cenomanian marine series. The present work introduces a synthesis of stratigraphical, sedimentological and micropalaeontological studies, which has led to new dating and to the identification of different depositional environments. These results have allowed us to define a new chrono-lithostratigraphic unit, the "Aït Bazza Formation", which comprises three superimposed members AB1-3 separated by two sedimentary discontinuities. This formation, exceeding 300 m in thickness, is formed by conglomerate, sandstone, sand and varicoloured marls. Micropalaeontological bulk sampling in marly horizons revealed associations of charophytes and ostracods, particularly in Member AB2. The charophytes are represented by oogonia of small Porocharaceae, Clavatoraceae such as Hemiglobator rectispirale, Dictyoclavator ramalhoi, and Nodosoclavator bradleyi that characterise the Tithonian. The ostracod microfauna is diverse, consisting of non-marine and lagoonal- shallow marine species at several horizons, associated with sea urchin spines and rare foraminifera, which indicate fluvio-deltaic sedimentary environments subjected to marine influences. This new age constraints of AB2 Mb to the Late Jurassic, and the discovery of marine influences in this eastern part of the folded Middle Atlas, consequently indicates the existence of palaeogeographical connections with the Tethyan domain located to the NE in the Rif foreland.

Several fossil beetles from the Late Pliocene (Piacenzian) of Willershausen (Lower Saxony, Germany) previously identified as Tenebrionidae and Staphylinidae are reviewed. One species, formerly determined as “Staphylinoidea” is identified as Euboeus mimonti Boieldieu, 1865 (Tenebrionidae: Helopini). This species is the oldest record of an extant species of darkling beetles, which occurs now in the Balkans and Anatolia. The discovery of Euboeus mimonti in the Late Pliocene of Germany indicates that the range of this species was much wider, and the climate in the Late Pliocene in the modern territory of Lower Saxony was much milder. One species formerly determined as “Alleculidae gen. sp.” belongs to the subfamily Alleculinae (Tenebrionidae) and it is identified here as Pseudocistela aff. ceramboides. Two species, misidentified by a previous author as Tenebrionidae belong to Elateridae and Cerambycidae respectively. Generic and species composition, as well as the ratio of extinct and extant beetle taxa in the Willershausen Fossil Lagerstätte are discussed.