Scleractinian corals of suborders Pachythecaliina and Rhipidogyrina : discussion on similarities and description of species from Štramberk-type limestones, Polish Outer Carpathians

Similarities between scleractinian corals from extinct suborders Pachythecaliina Eliášová 1976 and Rhipidogyrina Roniewicz 1976 are discussed. Corals of the former suborder are considered by some authors as possible descendants of Palaeozoic Rugosa because of their unusual skeletal characters. Some rhipidogyrinans, especially the family Aulastraeoporidae, despite their different septal microstructure, share more common features with pachythecaliinans than with other scleractinians. The following skeletal features are discussed to show similarities between these two suborders: (1) wall microstructure and its relations to septa, (2) corallite bilateral symmetry, (3) marginarium, (4) lonsdaleoid and apophysal septa, and (5) internal septal margin. These similarities can be explained by convergence, although phylogenetic relationships of both suborders can not be excluded. This hypothesis needs to be verified by more studies, especially on early blastogeny of rhipidogyrinans and wall microstructure of pachythecaliinans. The systematic part gives descriptions of the discussed coral suborders occuring in the Štramberk-type limestones, the Polish Outer Carpathians (Tithonian-?Berriasian, ?Valanginian). Similarly as in the Štramberk Limestone (Moravia), pachythecaliinans are highly diversified (17 species, 12 genera, including Pachythecophyllia eliasovae n.gen., n.sp.). Rhipidogyrinans are represented by 4 species of 4 genera, including ?Ogilvinella morycowae n.sp

Taphonomic differentiation of Oxfordian ammonites from the Cracow Upland, Poland

Taphonomic analysis of Lower and Middle Oxfordian ammonites from the Cracow Upland, southern Poland (localities at Podłęże, Zalas, Młynka) revealed differences in ammonite preservation. The studied ammonites, usually termed as external and internal moulds, show a more complex state of preservation. In the Middle Oxfordian glauconitic marls, ammonites are preserved as internal moulds with neomorphic calcite shells showing relics of the original internal structure. In the Middle Oxfordian platy peloidal limestones, ammonites are preserved mostly as external moulds, without septal suture, however under microscope might show relics of internal whorls and septa and/or subtle differences in sediment filling phragmocone chambers. In sponge–microbial bioherms and biostromes, ammonite internal moulds have shells, which in contrast to ammonites from glauconitic marls are not strictly neomorphic ones, but originated by shell dissolution and subsequent filling of moldic porosity by calcite cement. In sponge–microbial nodular limestones, the ammonites are strongly deformed and the outer wall is usually removed by dissolution under pressure. Other important taphonomic differences include the rate of compaction (highest in platy limestones), sedimentary infillings, microborings, encrustations and preservation of siphuncular tubes. The majority of the ammonites appear to be phragmocones; aptychi in all facies are rare. Siphuncular tubes are fossilized exclusively in oppeliids, only in specimens from glauconitic marls and platy limestones, although their other taphonomic attributes are different. Tubes seem to have fossilized due to microbially mediated phosphatization that could be favoured by a set of parameters which operated rather at the scale of ammonoid carcasses: closed, poorly oxygenated conditions, and reduced pH. Taphonomic processes were controlled by the sedimentary environment (fragmentation, sedimentary filling, phosphatization of siphuncular tubes), as well as by early and late diagenesis (neomorphic transformation, dissolution, cementation, compaction) influenced by lithology

Tithonian-Berriasian calpionellids from the Štramberk-type limestones, Polish Flysch Carpathians

Calpionellid fauna from the coral-bearing exotics of the Štramberk limestones from Polish Flysch Carpathians has been studied. Calpionellids of the Remanei Subzone and the Intermedia Subzone as well as the Calpionella Zone indicate the Late Tithonian (most of exotics) and the Early Berriasian age of exotics studied. In contrast to the Štramberk Limestone (Moravia), calpionellids of the Chitinoidella Zone have not been recognized in the studied material

Prolific development of pachythecaliines in Late Barremian, Bulgaria : coral taxonomy and sedimentary environment

Diversified and abundant corals of the suborder Pachythecaliina (order Hexanthiniaria) are described from Upper Barremian, biostromal reefs of the Emen Formation, Lovech Urgonian Group, north central Bulgaria. The corals are mostly of the phaceloid growth form and represent 14 species (six new), 12 genera (three new), belonging to five families. Pachythecaliines occur with the small, monopleurid cylindrical rudist Mathesia darderi. The rudists frequently are densely clustered, occur between coral branches or are in contact with them. Other corals, with the exception of the phaceloid Calamophylliopsis, and other rudists, are rare. Non-laminated microbialite crusts provided additional, structural support for bioconstruction development. Microbialites (automicrites) can be interpreted as a product of microbial activity, or alternatively, as a result of carbonate precipitation, brought about by non-living organic substrates (organomineralization s.s.). In addition to microbialites, metazoans are encrusted by heterotrophic skeletal microorganisms, while photophilic and oligotrophic microencrusters, usually common in other coral-bearing limestones of the Emen Formation, are very rare. The section at the Rusalya Quarry (NW of Veliko Tarnovo), about 42 m thick, provides the sedimentary and environmental context for the reefal biostromes. The vertical biotic and sedimentary succession displays a general shallowing trend: from the outer carbonate platform with bioclastic limestones containing small boundstone patches (corals, but not pachythecaliines, Lithocodium aggregatum), to the inner platform with rudist biostromes. The pachythecaliine-rich biostromes, 2.5 m thick, were developed in a low-energy environment, referred to the distal part of the rudist-dominated area of the platform. The development of microbialites was facilitated by a low sedimentation rate, and possibly by increased nutrient level. Only poorly diversified and non-phaceloid pachythecaliines occur in other coral-rich limestones and marls of the Urgonian complex in Bulgaria. The assemblage described is the most remarkable, Early Cretaceous coral community worldwide, with regard to pachythecaliines. Phaceloid pachythecaliines are only more common in the Upper Jurassic rocks, being particularly diversified in the Tithonian-Lower Berriasian Štramberk Limestone (Czech Republic) and its equivalent in the Polish Outer Carpathians. However, their sedimentary context differs from that described for the corals of the Emen Formation

Diverse nature of ubiquitous microborings in Cenomanian corals (Saxonian Cretaceous Basin, Germany)

Upper Cenomanian rocky shore conglomerates exposed in the abandoned Ratssteinbruch quarry in Dresden (Saxonian Cretaceous Basin, Eastern Germany) contain numerous small coral colonies. The skeletons are commonly encrusted with thin ferruginous microbial crusts. Skeletal elements, especially radial elements (septa), contain abundant microborings filled with iron oxyhydroxides. Natural casts of microborings were studied under SEM. Two categories of microborings (2-12 μm in diameter) were distinguished in respect of their time of production. Type 1 microborings occur in the inner part of the colonies and are typically distributed more or less along the septa in the direction of the coral growth. This type is represented by Ichnoreticulina elegans (most common traces; produced by chlorophyte green alga), Scolecia filosa (traces of cyanobacteria), and much more rarely by Conchocelichnus seilacheri (traces of red algae). They were produced during coral life (in vivo), and provide insight into the very poorly recognised skeleton microbiome of fossil corals. Chlorophyte alga Ostreobium quekettii - the most common microendolith in the skeletons of living modern corals - produces I. elegans, which dominates the Type 1 microborings. Type 2 microborings include I. elegans, S. filosa, Scolecia serrata (made by bacteria) and undetermined microborings. They occur directly below the microbial crusts coating the entire colony, or below thin ferruginous films coating the surfaces of skeletal elements. Microborings are distributed randomly or are more or less perpendicular to skeleton surfaces, demonstrating that Type 2 microborings were evidently made by microendoliths after coral death (post-mortem), when skeletal elements were exposed

Simple methods for detection of microborings produced by coral-associated microendoliths

Well-preserved skeletons of Paleocene and Eocene scleractinians and octocorals (Polytremacis sp.) from Poland and Ukraine were studied to reveal microborings produced in vivo by coral-associated microendoliths. Microborings (mostly < 5 \mu m in diameter) are hardly visible, if at all, under a petrographic microscope. Their resin casts are obtained, however, through the epoxy vacuum cast-embedding technique and observed under a scanning electron microscope (SEM). Three-dimensional resin-filled (cast) microborings are also clearly visible under SEM in acid-etched petrographic thin-sections. Backscattered scanning electron microscopy imaging (BSE) is useful for visualization of the microborings during SEM study of both etched and non-etched thin-sections. A simple but very effective method to reveal the dense network of resin casts of microborings is observations of etched thin-sections under the petrographic microscope. Fluorescence microscopy (FL), especially with application of blue and green filters (Nikon’s B-1A and G-2A filter cubes), is recommended if etching thin-sections or polished samples is not possible. However, color contrast between the resin casts and the calcium carbonate of the coral skeleton was strong enough only in some examined thin-sections. The cathodoluminescence microscopy, the other method, does not require the etching of the thin-sections and is potentially useful for detection of microborings filled with calcite cement, although this technique was not applicable for the samples studied. Symbiotic coral-microendolith association (in broad meaning of the term symbiosis) is a common phenomenon in modern corals, but its fossil record is very sparse. This study shows that empty microborings can be common in fossil corals, allowing preparation of the resin casts. Some of the tested methods permit rapid detection of resin-filled microborings in thin-sections even by non-specialists, and selection of samples for SEM studies. Corals from claystones and mudstones, usually less affected by diagenesis, have higher taphonomic potential for preservation of empty microborings than corals from reef facies. The methods discussed here can be also applied for rapid detection of post-mortem microborings occurring in other substrates

Improving detection of foraminifera by cathodoluminescence

Cathodoluminescence (CL) studies of Lower-Middle Oxfordian marls and limestones, as well as clasts from the uppermost Turonian-?Early Coniacian conglomerates of the Cracow Upland (southern Poland), reveal that the CL view of foraminifers from some lithologies differs from that in transmitted light. In particular, the CL technique revealed abundant tests of planktonic species Globuligerina oxfordiana in the Middle Oxfordian glauconitic marls, which under transmitted light are either poorly visible or remain completely undetected. Bright red-orange luminescence characterizes originally hyaline aragonitic tests of G. oxfordiana, but also several calcitic benthic species, in spite of their different taxonomic position and original test structure and mineralogy. In sponge microbial boundstones, foraminifers generally do not show the CL emission, or show a weak luminescence. Similarly, Late Cretaceous foraminifera represented mostly by planktonic taxa were detected or their view was clearly improved under CL only in some clasts from the uppermost Turonian-?Early Coniacian conglomerates filling karstic cavities. In other clasts, foraminifera are clearly visible only under normal transmitted light, therefore the luminescence signature is highly spatially variable. These results indicate a strong influence of lithology and diagenesis and rather minor effects of shell structure on luminescence of microfossils. The CL technique can be a useful tool in the detection and documentation of abundance patterns of foraminifers that are poorly preserved under transmitted light

Oxfordian to Valanginian palaeoenvironmental evolution on the western Moesian Carbonate Platform : a case study from SW Bulgaria

Three sections (Rebro, Lyalintsi and Velinovo) of the Upper Jurassic-Lower Cretaceous carbonate sequences from the Lyubash unit (Srednogorie, Balkanides, SW Bulgaria) have been studied for elucidation of biostratigraphy and palaeoenvironmental evolution. Palaeontological studies of foraminifera, supplemented by studies of calcareous dinoflagellate cysts and corals, enabled the determination of the Oxfordian-Valanginian age of the analysed sequences. They were deposited on the Dragoman Block (western part of the Moesian Platform), and during Mid-Late Cretaceous included to the Srednogorie. A possible Middle to Late Callovian age of the lowermost part (overlying the Bajocian-Lower Bathonian Polaten Formation) of the studied sections assumed till now has not been confirmed by the present studies. Eleven facies have been distinguished and attributed to depositional environments. Marine sedimentation on a homoclinal ramp started in the Oxfordian and till the Early Kimmeridgian - in all three sections - was dominated by fine-grained peloidal-bioclastic wackestones to grainstones. Since the Late Kimmeridgian, when a rimmed platform established, facies pattern underwent differentiation into (i) the inner platform (lagoon and tidal flat facies) - only in Velinovo, (ii) reef and peri-reef facies/bioclastic shoals - mainly in Lyalintsi, and (iii) platform slope - mainly in Rebro. Sedimentation generally displays a shallowing-upward trend. Two stages in evolution of the rimmed platform are postulated. The mobile stage lasting till the Tithonian/Berriasian boundary was followed by a more stable stage in the Berriasian to Valanginian time. Reefs are developed mainly as coral-microbial biostromes, lower coral bioherms or coral thickets, in the environment of moderate energy and sedimentation. They contain highly diversified corals (72 species). Micro- bialites contributed to the reef framework, but they never dominated. Locally, microencrusters and cement crusts formed important part of reefal framework. During the mobile stage of the platform evolution a relative sea-level rise interrupted reef development, as evidenced by intercalations of limestones with Saccocoma. During the second stage high carbonate production and/or regressive eustatic events, not balanced by subsidence, decreased accommodation space, limiting reef growth and enhancing carbonate export to distal parts of the platform