Devonian conodont biogeography: Quantitative analysis of provinciality

Cluster analysis of conodont faunas from each of 17 Lower‐lower Upper Devonian zones and subzones (data as reported by Klapper and Johnson, 1980) reveal changing patterns of provinciality.

Provinciality, expressed by a differentiation into western Laurussian and proto‐Tethyan biogeographic regions, is moderate in the lower Lochkovian but is low or absent in the upper Lochkovian‐lower Pragian. Provincialism returns in the Pragian and reaches its maximum development during the Emsian. Most Australian faunas are distinct from those of western Laurussia and the proto‐Tethys. Conodont faunas from suspect terranes of western North America display no unusual biogeographic affinities. Provincialism declines during the Eifelian and is only weakly developed in Givetian‐lower Frasnian faunas.

Changing global sea level during the Devonian may explain the development of Devonian conodont provinciality. As proposed by Klapper and Johnson (1980), low provinciality is associated with low stands of sea level. Endemic faunas develop in isolated epeiric seas during intermediate stages of sea level rise. High stands of sea level ultimately drown barriers to faunal exchange and prompt a return to low provinciality conditions.     

Upper Moscovian-middle Kasimovian conodonts (Pennsylvanian, Carboniferous) from the Las LLacerias Section (Cantabrian Zone, north Spain)

Las LLacerias Section in the western part of the Picos de Europa Unit (Cantabrian Zone) in northern Spain offers the best (essentially continuous) Upper Moscovian-Kasimovian succession in the Pennsylvanian of the Cantabrian Zone. The section consists almost entirely of limestones, and conodonts are scarce in general, but some Myachkovian levels are significantly more productive. Most specimens recovered are Pa pectiniform elements, and are generally well preserved. Idiognathodus, Streptognathodus, Gondolella, and Neognathodus are the most significant genera and Ubinates and Hindeodus are present. Idiognathodus is the dominant genus. Most of the idiognathodids differ morphologically from those elsewhere, and one, Idiognathodus covadongae, is formally recognized a new species. The presence of Idiognathodus eccentricus in the upper part of the Kreviakinian levels suggests a correlation with the lower Missourian of the United States. Neognathodus disappears in the upper part of the Myachkovian beds. Gondolella pohli was recovered from a short interval in the upper portion of the Myachkovian beds. Paleoecological conditions representing shallow, open, normal marine offshore deposits of the Idiognathodus-biofacies are interpreted for the lower portion of the Myachkovian interval.     

A universal strategy for high-yield production of soluble and functional clostridial collagenases in <Emphasis Type="Italic">E. coli</Emphasis>

Clostridial collagenases are foe and friend: on the one hand, these enzymes enable host infiltration and colonization by pathogenic clostridia, and on the other hand, they are valuable biotechnological tools due to their capacity to degrade various types of collagen and gelatine. However, the demand for high-grade preparations exceeds supply due to their pathogenic origin and the intricate purification of homogeneous isoforms. We present the establishment of an Escherichia coli expression system for a variety of constructs of collagenase G (ColG) and H (ColH) from Clostridium histolyticum and collagenase T (ColT) from Clostridium tetani, mimicking the isoforms in vivo. Based on a setup of five different expression strains and two expression vectors, 12 different constructs were expressed, and a flexible purification platform was established, consisting of various orthogonal chromatography steps adaptable to the individual needs of the respective variant. This fast, cost-effective, and easy-to-establish platform enabled us to obtain at least 10 mg of highly pure mono-isoformic protein per liter of culture, ideally suited for numerous sophisticated downstream applications. This production and purification platform paves the way for systematic screenings of recombinant collagenases to enlighten the biochemical function and to identify key residues and motifs in collagenolysis.     

Morphogenesis,origin, and paleoecology of the bryozoans of the family Medvedkellidae fam. nov. (Upper Carboniferous,East European Platform)

A new family of the order Rhabdomesida, Medvedkellidae fam. nov., is described. This family consists of a new genus, Medvedkella gen. nov., comprising three species transferred from the genus Rhombopora Meek, 1872: the type species M. riasanensis (Schulga-Nesterenko, 1955), M. diaphragmata (Schulga-Nesterenko, 1955), and M. mariae (Dunaeva, 1961). The morphogenesis of the first two species is studied. For the first time axial zooecia are revealed in the suborder Golgdfussitrypina, which existed in parallel with the suborder Rhabdomesina of the order Rhabdomesida. A hypothesis that the new family evolved from the subfamily Nicklesoporinae Gorjunova, 1985 of the family Goldfussitrypidae, 1985 is proposed. Some questions of the ecological adaptation of these bryozoans in the Late Carboniferous marine basin of the East European Platform are discussed.     

Organic compositions of the embryo-bearing lowermost Cambrian Kuanchuanpu formation on the northern Yangtze platform, China

We investigated the origin of organic matter and paleoceanographic conditions of the embryo-bearing lowermost Cambrian Kuanchuanpu Formation in Shaanxi Province, China, in terms of sedimentary facies, fossil morphometry, and organic geochemistry, including biomarker compositions. The results indicated the abundance of algae and eukaryotic phytoplankton that fueled a diverse ecosystem including cnidarians and small shelly fossils. The water column contained enough oxygen to provide habitat for benthic cnidarians such as Olivooides. On the other hand, low pristane/phytane ratios, detection of squalane, and hopane composition indicate reductive conditions within the sediments, and that the redox front was likely near the water-sediment interface. Common occurrences of pyrite and barite indicate that redox reactions of sulfur species were activated at the water-sediment interface. Such circumstances and the high phosphate concentration in ambient water may recall the presence of sulfur-oxidizing bacteria that promoted the phosphatization of animal embryos, as suggested for in the Neoproterozoic Doushantuo Formation. Nitrogen was the limiting nutrient for primary productivity, and the high phosphate concentration in the ocean promoted the phosphatization of animal embryos at the reductive water–sediment interface.     

New Cambrian lobopods and chaetognaths of the Siberian Platform

The association of isolated remains of lobopods with a netlike structure, including plates of Microdictyon rozanovi sp. nov. and sclerites with spinelike process of Onychomicrodictyon spiniferum gen. et sp. nov., as well as saberlike sclerites of Protohertzina yudomica sp. nov. interpreted as grasping spines of chaetognaths, is described from the middle part of the Inikan Formation of the Toyonian Stage of the Lower Cambrian (Lermontovia dzevanovskii Zone). The diagnoses and species composition of the genera Microdictyon and Protohertzina are refined.     

On the ontogeny and orientation of the Triassic Conodont P1-element in Pseudofurnishius murcianus Van den Boogaard, 1966

Successive growth stages of P1-elements in the Middle to early Late Triassic species Pseudofurnishius murcianus allows the observation of a detailed ontogeny. Besides the gradual enlargement of its curved blade and the growing number of its denticles, a small internal platform develops, eventually followed by an external one, both bearing denticles. The number of denticles on the blade and internal platform increases from five and one in the smallest specimens, respectively, to 14 and 9 in fully developed ones, whereby the distribution pattern of platform-denticles, on the inner one in particular, is of great morphological variety. For the orientation of the P1-element of P. murcianus, the comparison of the early development stages of Pseudofurnishius and Sephardiella, that share a common ancestry, permits to adhere to the orientation used by Diebel rather than to the one proposed by Van den Boogaard.     

浙江黄芝山剖面二叠-三叠系界线附近的牙形类序列及其地层对比

首次系统研究浙江黄芝山剖面二叠-三叠系界线附近的牙形类化石,共鉴定2属16种,并据此识别出5个牙形类化石带,从下至上依次为:Clarkina changxingensis changxingensis带,C.parasubcarinata带,C.chan-gxingensis yini-C.meishanensis zhangi带,C.meishanensis meishanensis带,Hindeodus parvus带。Hindeodus changxingensis,H.eurypyge,H.parvus分别在第15层、第18层底部、第18层中部依次出现,为确定该剖面二叠-三叠系界线在18-3层之底提供了依据。作者还讨论黄芝山剖面二叠-三叠系界线附近的牙形类序列与浙江煤山、伊朗剖面二叠-三叠系界线层牙形类序列的对比。     

The Pragian-Emsian conodont successions of the Barrandian area: search of an alternative to the GSSP polygnathid-based correlation concept

Six Pragian-Emsian boundary sections in the Barrandian area, western of Prague, provided evidence of well detectable entries of Latericriodus fauna probably at the earliest Emsian beds (particularly Latericriodus bilatericrescens gracilis Bultynck). The chance to find icriodontid conodonts increases with latest part of Praha Fm., which is apparently of Emsian age, whereas polygnathids are sparsely preserved to absent. The high icriodontid/polygnathid ratio links together all these Barrandian sections, although their open-sea depositional environments range widely from deep troughs with rapid calciturbidite accumulation (Pod Barrandovem section) to relatively starving slope environments on elevations (Na Po?árech sections). The reports on polygnathid occurrences around the Pragian-Emsian boundary beds of the Barrandian area are much biased by poor reproducibility of the results (the conodonts cannot be found again) as well as by different levels where they were randomly found and/or by major taxonomic problems with the “kitabicus” and “dehiscens” definitions and their stratigraphic use. Apart from the GSSP in the Zinzilban Gorge (Uzbekistan) and its “kitabicus” boundary, the newly introduced “gracilis” biostratigraphic-marker concept preserves the major volume of the Pragian and respects also approximately the base of the traditional Emsian. These “gracilis” entries are clustered around the dark-colored “graptolite-bearing interval” beds, which largely form a prominent lithological marker within the latest, light gray-colored Dvorce-Prokop Limestone of the Barrandian area. This “gracilis” biostratigraphic marker has a promising correlation potential relative to Spanish and Moroccan sections.