Search Results (6)

The Xingyi Fauna yields abundant and well-articulated skeletons of Ladinian (Middle Triassic, ab. 240 Ma) marine reptiles, associated with fishes, conodonts, crinoids, ammonoids, bivalves, arthropods, and other fossils including nannofossils and coprolites. It represents a new marine ecosystem fully developed after the end-Permian Mass Extinction, and characterized by the appearance of a diversity of large marine reptiles with large ichthyosaurs as the apex predators. Twenty marine reptile and 17 fish species have been reported. The sequence of the Xingyi Fauna records the transition from a marine ecosystem dominated by air-breathing tetrapods extending across the shallow platform to the deep ocean, as indicated by large marine reptiles with a capability for long-distance cruising into the outer sea. The faunal composition of the Lower Assemblage of the Xingyi Fauna, dominated by small- to medium-sized pachypleurosaurids and nothosaurids, is similar to that of the older Anisian Panxian Fauna and the western Tethyan Monte San Giorgio Fauna, but the faunal composition of the Upper Assemblage, with large ichthyopterygians, pistosauroid sauropterygians, and flying fishes, is similar to that of the younger Carnian Guanling Biota as well as the Raibl and Polzberg Faunas in the Alps and California. Therefore, the Xingyi Fauna can be considered a hub of paleobiogeological exchange connecting the western Tethys and the eastern Pathalassa. Full article

The Nubia Sandstone in the Gulf of Suez, Egypt, is a well-known unclassified sediment. Palynology is considered the most effective tool for dealing with this problem. Miospore assemblages from the Lowermost Carboniferous (Tournaisian) have been discovered from the J62-86 and the J62-64 AST1 wells located in the July Field of the Gulf of Suez, Egypt. Spores are moderately to poorly preserved, suggesting a stratigraphical position within Lowermost Carboniferous ages. The studied sediments include poorly preserved conodont fragments and present significant identification challenges due to the drilling methodologies’ complexities. Spore assemblage consists of 31 genera with 56 species. The dominant spores include zonate genera Vallatisporites, Densosporites, and Archaeozonotriletes, camerate genera Grandispora, Geminospora, apiculate genera Apiculiretusispora, and laevigate trilete genus Punctatisporites and megaspores of the Lagenoisporites type are recorded. Marine microphytoplankton including Schizocystia bicornuta, Lophosphaeridium, Leiosphaerida, and some filamentous green algae of unknown affinity are recorded. The dispersed spore assemblage is associated with carbonized plant fragments. The palynological data have effectively dated the lower intervals of the Nubia Sandstone from the Nubia “B,” indicating a Lowermost Carboniferous (Tournaisian) age, i.e., Vallatisporites vallatus–Retustriletes incohatus palynozone (VI). The stratigraphic differentiation of the Nubia Sandstone is crucial for subsequent correlating subsurface wells in the Gulf of Suez within the context of geology and hydrocarbon exploration, particularly given the scarcity of other fossil groups. Full article

In the Baltic States and Belarus, the Middle Devonian period is characterised by an abundant fossil record of invertebrates such as scolecodonts, brachiopods, ostracods, trilobites, bivalves, crinoids, gastropods, and tentaculites. On the other hand, there was limited diversity in the conodont and other vertebrate fauna. In this study, we introduce a newly refined ichthyofaunal assemblage from the Eifelian and Givetian epochs from the present-day regions of Belarus and Lithuania. The isolated scales of Cheirolepis are identified as C. gaugeri, C. cf. gaugeri, C. aleshkai, C. cf. aleshkai, and Cheirolepis sp., while Orvikuina is represented by the isolated scales of O. vardiaensis and Orvikuina sp. The histological analyses for the scales of Orvikuina are provided here. Moreover, Orvikuina and Cheirolepis taxa are now recognised to be widely distributed throughout the Baltic States, especially Lithuania and Belarus, as a result of these findings. Thus, this ichthyofaunal data markedly improved the biostratigraphic correlation within the study region and expanded the paleogeographic distribution of these taxa during the Eifelian and Givetian time in Laurasia. Full article

As one of the predominant benthic organisms in the Palaeozoic, brachiopod was largely eliminated in the Permian–Triassic boundary mass extinction, and then highly diversified in the Middle Triassic. Since fossil data from the Early Triassic are rarely reported, the recovery patterns of Early Triassic brachiopods remain unclear. This study documents a well-preserved fauna that is the most diverse Olenekian brachiopod fauna so far (age constrained by conodont biostratigraphy) from the Datuguan section of ramp facies in South China. This fauna is composed of 14 species within nine genera, including six genera (Hirsutella, Sulcatinella, Paradoxothyris, Dioristella, Neoretzia and Isocrania) found in the Early Triassic for the first time and three new species, including Paradoxothyris flatus sp. nov., Hirsutella sulcata sp. nov. and Sulcatinella elongata sp. nov. The Datuguan fauna indicates that the diversity of Olenekian brachiopod fauna has been underestimated, which can be caused by a combination of reduced habitats (in geographic size and sedimentary type) compared with the end-Permian, great bed thickness making it difficult to find fossils and most species in the fauna having low abundance. Based on the faunal change in the Datuguan section and environmental changes in South China, it can be inferred that brachiopod recovery in the studied section occurred in the latest Spathian rather than the Smithian when the environment started to ameliorate. Global brachiopod data also indicates that the initial recovery of brachiopods happened in the Spathian, and many genera that widely occurred in the Middle or Late Triassic had originated in the Olenekian. Full article

This report provides oxygen isotopes from apatite of late Middle and Late Ordovician conodonts from the southern Holy Cross Mountains in south-eastern Poland. It was a unique time interval characterised by a significant change in the Ordovician climate, tectonic, and ocean chemistry. In the Middle and early Late Ordovician, the Holy Cross Mountains were located in the mid-latitude climatic zone at the southwestern periphery of Baltica; therefore, the δ¹⁸O_apatite values from this region provide new data on the ¹⁸O/¹⁶O budget in the Ordovician seawater reconstructed mainly from the tropical and subtropical realms. Oxygen isotopes from mixed conodont samples were measured using the SHRIMP IIe/MC ion microprobe in the Polish Geological Institute in Warsaw. The δ¹⁸O_apatite values range from 16.75‰_VSMOW to 20.66‰_VSMOW with an average of 18.48‰_VSMOW. The oxygen isotopes from bioapatite of the studied section display an increasing trend, suggesting a progressive decrease in sea-surface temperature roughly consistent with an overall cooling of the Ordovician climate. Two distinctive positive excursions of δ¹⁸O_apatite have been reported in the upper Sandbian and middle Katian of the studied section and correlated with cooling events recognised in Baltica. They are interpreted as an isotope temperature proxy of climate changes triggered by a growing continental polar ice cap, but increased δ¹⁸O_apatite in the late Sandbian contradicts recently postulated climate warming during that time in subtropical Laurentia. Full article

The Global Stratotype Section and Point (GSSP) of the Silurian/Devonian boundary, Lower Devonian Series and Lochkovian Stage was formally placed in 1977 at Klonk, in the Czech Republic, at the first appearance of the graptolite Uncinatograptus uniformis uniformis (Přibyl). However, since then, correlation of this limit has been often hampered in carbonate facies where graptolites are uncommon or totally absent. A large calcareous deposition occurred at the Silurian/Devonian boundary along the northern and peri-Gondwana margin, thus representing an ideal location to select and test a possible additional biostratigraphic marker of the limit among conodonts. The first appearance of Caudicriodus hesperius almost simultaneously at the base of the Devonian in Bohemia, the Carnic Alps, Sardinia, Morocco and elsewhere indicates that this taxon is the conodont that best approximates the beginning of the Period. The first or last appearance of other species (e.g., Ozarkodina confluens, Zieglerodina klonkensis, Z. remscheidensis and Caudicriodus woschmidti) may help to recognise the boundary as well. Full article