Felix Schlagintweit

The morphological adaptation of Lithocodium aggregatum Elliott (calcareous green alga) to cryptic microhabitats (Lower Aptian, Spain): an example of phenotypic plasticity

Lithocodium aggregatum Elliott is interpreted as a heterotrichale chlorophycean alga with a prostrate and erect system within a well-calcified tissue. Within Lower Aptian coral rubble of the western Maestrat Basin, Spain, it forms thick masses of juxtaposed crusts around the bioclasts. In achieving a rapid and complete encrustation of the available bioclasts, Lithocodium applied several strategies, e.g., filling voids of structured surfaces with a special fabric or forming erect extensions to bridge adjacent substrates. In these deposits, different types of poorly if ever illuminated cryptic microhabitats can be distinguished: (1) existing crypts such as empty shells or structural voids within bioclasts (2) crypts resulting from the complete encrustation of adjacent bioclasts by Lithocodium itself and (3) syndepositionally created crypts, e.g., boreholes produced by lithophagid bivalves. In these cases, Lithocodium developed a poorly calcified structure of large cells with thin microcrystalline walls indicating a high degree of variability (phenotypic plasticity). This cryptic growth stage is interpreted as an adaption to the poorly illuminated crypts (photoadaption) in order to maximize light capture for photosynthesis. The Lower Cretaceous Lithocodium is therefore not per se a cryptoendolithic microorganism, but may show adaptation to develop and survive also in these already existing or newly created niches.

Iberopora bodeuri GRANIER & BERTHOU 2002 (incertae sedis) from the Plassen Formation (Kimmeridgian–Berriasian) of the Tethyan Realm

Iberopora bodeuri GRANIER & BERTHOU 2002, formerly known as “crust problematicum” (SCHMID, 1996) is described from the Plassen Formation (Kimmeridgian–Berriasian) of the Northern Calcareous Alps (NCA). Here, it occurs either as an incrustation on corals/stromatoporoids or it forms nodular masses (“solenoporoid morphotype”). It is typically found in the fore-reef facies of the platform margin, and (upper) slope deposits where autochthonous dasycladales are absent. Water turbulence appears to control the morphological development of Iberopora. Thus, flat crusts appear in less agitated settings. The crusts are almost always accompanied by calcareous sponges/sclerosponges and abundant micro-encrusters, mostly Koskinobullina socialis CHERCHI & SCHROEDER and “Tubiphytes” morronensis CRESCENTI. The stratigraphic range of Iberopora known to date is Oxfordian–Berriasian. In addition to the Northern Calcareous Alps, it has been reported from the epicontinental area of NW-Germany, the northern margin of the Penninic and Tethyan ocean (Slovakia, Switzerland, Spain, Poland, Portugal) and the southern Tethyan domain (Greece, Romania, Yugoslavia). Until other morphological elements (e.g. reproductive organs or protoconch) are found, its systematic position remains uncertain. Currently, it is considered questionably to be an ancestral rhodophyceae or acervulinid-like foraminifera.

Ophiolitic detritus in Kimmeridgian resedimented limestones and its provenance from an eroded obducted ophiolitic nappe stack south of the Northern Calcareous Alps (Austria)

Abstract The causes for the Middle to Late Jurassic tectonic processes in the Northern Calcareous Alps are still controversially discussed. There are several contrasting models for these processes, formerly designated “Jurassic gravitational tectonics”. Whereas in the Dinarides or the Western Carpathians Jurassic ophiolite obduction and a Jurassic mountain building process with nappe thrusting is widely accepted, equivalent processes are still questioned for the Eastern Alps. For the Northern Calcareous Alps, an Early Cretaceous nappe thrusting process is widely favoured instead of a Jurassic one, obviously all other Jurassic features are nearly identical in the Northern Calcareous Alps, the Western Carpathians and the Dinarides. In contrast, the Jurassic basin evolutionary processes, as best documented in the Northern Calcareous Alps, were in recent times adopted to explain the Jurassic tectonic processes in the Carpathians and Dinarides. Whereas in the Western Carpathians Neotethys oceanic material is incorporated in the mélanges and in the Dinarides huge ophiolite nappes are preserved above the Jurassic basin fills and mélanges, Jurassic ophiolites or ophiolitic remains are not clearly documented in the Northern Calcareous Alps. Here we present chrome spinel analyses of ophiolitic detritic material from Kimmeridgian allodapic limestones in the central Northern Calcareous Alps. The Kimmeridgian age is proven by the occurrence of the benthic foraminifera Protopeneroplis striata and Labyrinthina mirabilis, the dasycladalean algae Salpingoporella pygmea, and the alga incertae sedis Pseudolithocodium carpathicum. From the geochemical composition the analysed spinels are pleonastes and show a dominance of Al-chromites (Fe3+–Cr3+–Al3+ diagram). In the Mg/(Mg+ Fe2+) vs. Cr/(Cr+ Al) diagram they can be classified as type II ophiolites and in the TiO2 vs. Al2O3 diagram they plot into the SSZ peridotite field. All together this points to a harzburgite provenance of the analysed spinels as known from the Jurassic suprasubduction ophiolites well preserved in the Dinarides/Albanides. These data clearly indicate Late Jurassic erosion of obducted ophiolites before their final sealing by the Late Jurassic–earliest Cretaceous carbonate platform pattern.

Onset of an Aptian carbonate platform overlying a Middle-Late Jurassic radiolaritic-ophiolithic mélange in the Mirdita Zone of Albania

Late Jurassic and Early Cretaceous carbonate sediments of different age and facies, form the post-emplacement settings on top of the Mirdita Ophiolite Zone in northern Albania. They seal the early Late Jurassic emplacement of the ophiolite knappes, are the only datable relics overlying the ophiolites in the Late Jurassic - Early Cretaceous, aiding the evaluation of the different tectonic movements associated with uplift and erosion as well as sea-level fluctuations during that time span. These carbonates overlie ophiolite-derived clastics very often as shallowing-upward sequences. One of the largest shallow-water platforms is the Mali I Shenjtit platform, previously assigned to the Barremian-Aptian. A well-preserved section at the base of the platform can be ascribed to the Early-Late Aptian based on orbitolinid foraminifera together with dasycladalean algae. This carbonate platform is the youngest preserved Early Cretaceous platform in Albania, but was largely eroded away. Late Cretaceous shallow-water rudist limestones are widespread and preserved in the Dinaride-Albanide-Hellenide realm directly above an eroded older basement. Therefore, this Aptian platform is very important for the reconstruction of the Early Cretaceous palaeogeography in the northwestern Neotethyan realm. In addition, the stratigraphic ranges of characteristic Aptian orbitolinid foraminifera, Rectodictyoconus giganteus SCHROEDER and Mesorbitolina texana (ROEMER), are discussed on the basis of these results.

Neogyroporella? gawlicki n.sp., a New Dasycladale from the Upper Jurassic–Lower Cretaceous “Lärchberg Formation” of the Northern Calcareous Alps, Austria

A new Dasycladale (calcareous green alga) is described as Neogyroporella? gawlicki n.sp. from the Upper Jurassic–Lower Cretaceous “Larchberg Formation” of the Northern Calcareous Alps, Austria. It is distinguished from the type-species Neogyroporella elegans YABE & TOYAMA (Upper Jurassic of Japan; currently the only representative of the genus), by its distinctly smaller dimensions and a higher number of laterals. The generic attribution of the new taxon is discussed, including similarities/differences to allied genera, especially Humiella SOKAC & VELIC. Neogyroporella? gawlicki n.sp. is so far only known from the Northern Calcareous Alps. In addition, some other Dasycladales accompanying Neogyroporella? gawlicki n.sp. are also illustrated.

Coptocampylodon? rhaeticus n.sp., a New Problematic Microfossil ("incertae sedis") from the Rhaetian Dachstein Limestone of the Northern Calcareous Alps (Germany, Austria)

A new problematic microfossil is described as Coptocampylodon? rhaeticus n.sp. from the Rhaetian Dachstein Limestone of the Northern Calcareous Alps. The new species is composed of a long cylindrical and an irregular rounded body, both showing narrow axial cavity. It is similar to Coptocampylodon? elliotti RADOICIC 1969 from the Cenomanian of Montenegro, but lacks the longitudinal grooves in the cylindrical part. In the Alpine Dachstein Limestone it has been detected at several localities where it occurs as an abundant constituent of biosparitic limestones along with the benthic foraminifera Triasina hantkeni MAJZON, Aulotortus sinuosus WEYNSCHENK, Duostominidae and dasycladales Griphoporella curvata (GUMBEL) and Diplopora adnetensis FLUGEL.

The Paleozoic record of Thaumatoporella PIA, 1927?

From Palaeozoic (mainly Devonian) shallow-water carbonates, spherical to irregular shaped microfossils with thin, apparently homogeneous or perforate micritic walls are widely reported. They are classically referred either to unilocular parathuramminid foraminifera, algae incertae sedis or calcispheres (e.g., Bisphaera , Cribrosphaeroides , Uslonia , Vermiporella myna , Irregularina ). Due to their morphology and microstructural features, they are here reassessed more accurately as belonging to Thaumatoporella PIA, a widespread Mesozoic-Early Cenozoic taxon of incertae sedis showing a remarkably high morphological variability. In analogy to Mesozoic thaumatoporellaceans, Bisphaera malevkensis BIRINA is interpreted as the cyst (= resting) stage of forms ascribed to different genera, i.e., Cribrosphaeroides , Uslonia and Vermiporella (here: Vermiporella myna WRAY). This new interpretation leads to taxonomic reassessment as Thaumatoporella malevkensis (BIRINA) nov. comb. As a consequence of our interpretation, the rather long Mesozoic to Early Cenozoic (Ladinian to Early Ypresian) record of thaumatoporellaceans is supposed to be significantly larger than formerly assumed, showing four periods of increased abundance in the Middle/Late Devonian, Late Permian (?), Early/Middle Jurassic and Late Cretaceous time windows.

Foraminiferan tests and dasycladalean thalli as cryptic microhabitats for thaumatoporellacean algae from Mesozoic (Late Triassic–Late Cretaceous) platform carbonates

Thaumatoporellacean algae are widespread constituents in Middle Triassic–Cretaceous shallow-marine carbonates of the Tethyan realm. Based on various examples from Mesozoic limestones of Mediterranean platforms (e.g., Dinaric, Apenninic, Apulia) and rare records of Iberia (Pyrenees), Saudi Arabia and Mexico, it is shown that thaumatoporellaceans commonly dwelt as cryptoendoliths in the tests of larger benthic foraminifera and the thalli of dasycladalean algae. Their high morphological plasticity allowed the test invasion and the adaptation to the available interior spaces (chambers, apertures). The temporal distribution of cryptoendolithic thaumatoporellaceans with first records in the Late Triassic, shows acme intervals in Early–Middle Jurassic and Early–Late Cretaceous times. Within the foraminiferans, the thaumatoporellaceans were erroneously considered as an integral part of the test, respectively, phrenoteca-like structures (species Biokovina gradacensis) in the Lower Jurassic and trematophore (species Scandonea? mediterranea) in the Upper Cretaceous. Therefore, the presence of phrenoteca-like structures in the Biokovinidae, being part of the family diagnosis, is challenged. The comparably thin walls of the cryptoendolithic thaumatoporellacean algae are interpreted as an adaptation to the poorly illuminated microhabitats (photoadaptation) in order to maximize light capture for photosynthesis.

Mohlerina basiliensis (Mohler, 1938): a Middle Jurassic–Early Cretaceous facultative (?) epilithic benthic foraminifer

Mohlerina basiliensis (Mohler, 1938) represents a common, cosmopolitan, shallow-water Middle Jurassic–Early Cretaceous trochospiral foraminifer. Given the numerous illustrations from thin-section specimens in the literature displaying tests dispersed within the matrix (micritic and sparitic), a free, vagile benthic mode of life is generally suggested. As an exceptional case, specimens are found with their tests attached to a variety of hard substrates, thus creating a special elevated microhabitat. The fixation is due to a calcitic cement. With its facultative sessile mode of life, Mohlerina can be compared with several modern calcareous trochospiral rotaliacean foraminifera (e.g., Ammonia, Cibicides, Discorbis). The rare preservation of fixed Mohlerina in situ is most likely due to physical taphonomic degradation (e.g., breakage). Tests of Mohlerina attached to hard substrates were found in both low- and high-energy paleoenvironments. The high test variability of Mohlerina might be influenced by the different settling strategies and substrate surface topographies within different paleohabitats.

Gosavisiphon gen. nov. based on Halimeda paucimedullaris SCHLAGINTWEIT&EBLI, 1998: a remarkable macroalga (Udoteaceae?) from the Late Cretaceous of the Northern Calcareous Alps(Austria and Germany) with affinites to Late Paleozoic and Late Triassic phylloids

The new genus Gosavisiphon with the type-species Halimeda paucimedullaris SCHLAGINTWEIT & EBLI, 1998, tentatively referred to the Udoteaceae, is described from the Late Cretaceous (Middle/Late Cenomanian-Santonian) of the Branderfleck Formation and the Lower Gosau Subgroup of the Northern Calcareous Alps (Austria, Germany). It is a plurimillimetric to pluricentimetric marine, hard-substrate dwelling macroalga, with membraneous and partly fused plates and an internal siphonaceous construction but lacking a real medullary zone. Although some thallus details are still unknown, Gosavisiphon gen. nov. can, from a strictly morphological point of view, directly be compared with the Late Palaeozoic and Upper Triassic phylloid algae. Gosavisiphon gen. nov. is the first fossil record of a platy siphonal alga in the Cretaceous, since the Late Triassic Ivanovia triassica REID. The monotypic taxon is most probably endemic to the Northern Calcareous Alps where it dwelled in protected, terrestrially influenced lagoonal environments attaching to hard substrates, (metazoan skeletons, rudistid shells). Based on findings of the cylindrical Halimeda? aff. johnsoni PAL and another taxon described as Halimeda sp. with typically flattened ovate segments, some considerations on the segment-morphological phylogenetic evolution of Halimeda LAMOUROUX are provided. Halimeda species with discoidal-flattened segments, that can morphologically be compared with extant species, are not known prior to the Turonian. Forms possessing cylindrical segments date further back, but can not directly be compared morphologically with modern counterparts, thus placing doubts on the existence of long-lasting methusalemi species by uniting extant and fossil species, as proposed by both botanists and palaeontologists in recent times.