Palaeobiodiversity and Palaeoenvironments最新文献

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.