Upside down: ‘Cryobatrachus’ and the lydekkerinid record from Antarctica

Temnospondyl amphibians are common in non-marine Triassic assemblages, including in the Fremouw Formation (Lower to Middle Triassic) of Antarctica. Temnospondyls were among the first tetrapods to be collected from Antarctica, but their record from the lower Fremouw Formation has long been tenuous. One taxon, ‘Austrobrachyops jenseni,’ is represented by a type specimen comprising only a partial pterygoid, which is now thought to belong to a dicynodont. A second taxon, ‘Cryobatrachus kitchingi,’ is represented by a type specimen comprising a nearly complete skull, but the specimen is only exposed ventrally, and uncertainty over its ontogenetic maturity and some aspects of its anatomy has led it to be designated as a nomen dubium by previous workers. Here, we redescribe the holotype of ‘C. kitchingi,’ an undertaking that is augmented by tomographic analysis. Most of the original interpretations and reconstructions cannot be substantiated, and some are clearly erroneous. Although originally classified as a lydekkerinid, the purported lydekkerinid characteristics are shown to be unfounded or no longer diagnostic for the family. We instead identify numerous features shared with highly immature capitosaurs, a large-bodied clade documented in the upper Fremouw Formation of Antarctica and elsewhere in the Lower Triassic. Additionally, we describe a newly collected partial skull from the lower Fremouw Formation that represents a relatively mature, small-bodied individual, which we provisionally refer to Lydekkerinidae; this specimen represents the most confident identification of a lydekkerinid from Antarctica to date.

THE OLENEKIAN-ANISIAN/EARLY-MIDDLE TRIASSIC BOUNDARY, AND ASSESSMENT OF THE POTENTIAL OF CONODONTS FOR CHRONOSTRATIGRAPHIC CALIBRATION OF THE TRIASSIC TIMESCALE

The conodont Chiosella timorensis (Nogami, 1968) has for a long time been considered to be a suitable biotic proxy for the Olenekian-Anisian/Early-Middle Triassic boundary. The recently acquired ammonoid record around that boundary clearly shows that the FAD of this conodont is located well below the boundary, i.e., in the late Spathian. In the present paper, it is underlined that the conodont Chiosella timorensis was promoted as a proxy for the nominated boundary in the early 1980s when the ammonoid record around the boundary was not yet well established. On the other side, until the mid 1990s the taxonomic definition and the lineage of the conodont Chiosella timorensis were not well stated, and even now there are still controversial interpretations of the taxonomic content of this conodont species. The new data achieved from the ammonoid/conodont record around the nominated boundary, especially in the western USA, and also in the Deşli Caira section in Romania, firmly demonstrate that the conodont Chiosella timorensis is a defunct proxy for the Olenekian-Anisian/Early-Middle Triassic boundary. As a consequence, the present data on the ammonoid-documented Olenekian-Anisian/Early-Middle Triassic boundary requires the recalibration of all physical events that have been tied to the FAD of the conodont Chiosella timorensis. The case of the Albanian Kçira-section, for which the chronostratigraphic interpretation of the ammonoid record is proved incorrect, definitely makes the conodont Chiosella timorensis a defunct proxy for the nominated boundary. Also, the case of the two Chinese sections recently proposed as being “exceptional” GSSP candidates for the Early-Middle Triassic boundary, which is based on an inconsistent ammonoid/conodont biochronology, fully strengthens this conclusion. The history of the controversial usage of the conodont species Chiosella timorensis in defining the Olenekian-Anisian boundary justifies a discussion about the usefulness of conodonts in the chronostratigraphic calibration of the standard Triassic timescale. One may conclude that the conodonts are not qualified, and have not a reasonable potential, to be used to define or to redefine the boundaries of chronostratigraphic units in the standard Triassic timescale, which have been basically defined on ammonoid biochronology.

Preliminary results of XRF and XRD analyzes for lithofacial characteristics of the Doirentsi Formation reservoir carbonates in the south-central part of the Moesian Platform

The main objective of the study is to determine the lithofacial characteristics of the Doirentsi Formation reservoir carbonates in the range of the south-central part of the Moesian platform by XRD and XRF analyzes. The obtained results demonstrate the chemical and phase composition and supplement the field description of the Middle Triassic limestones and dolomites. This will allow the creation of realistic 3-D reservoir models for gas condensate fields Pisarovo and Devetaki in the future.

Triassic marine reptiles and other fossil vertebrates from the area of Godech, Western Bulgaria

Hitherto, the popular understanding was that the Bulgarian fossil record of Mesozoic tetrapods (four-limbed vertebrates) has been restricted to the Upper Cretaceous. In this contribution we report on the discovery of isolated bones of marine reptiles and teeth of various vertebrates from the Middle Triassic carbonate rocks outcropping near the town of Godech, Western Bulgaria. A revision of the currently held orthodoxy that Bulgaria is mostly a barren land when it comes to Mesozoic tetrapods is urged.

Estimation of quantitative criteria of carbonate reservoirs of triassic deposits

This paper discusses the boundary values of the reservoir properties of carbonate rocks of the Triassic sediments of South Mangyshlak, which are important for the interpretation of production geophysical data and for perforating and blasting operations. In terms of lithological composition, Triassic deposits are represented by two types of commercial reservoirs terrigenous and carbonate. Carbonate reservoirs are localized in the volcanic-dolomite and volcanic-limestone strata of the Middle Triassic. These rocks are characterized by a complex type of reservoir: porous-fractured, porous-cavernous and fractured. Sediments of the Upper Triassic occur with erosion on the Middle Triassic sedimentary complex and are represented by alternating tuffaceous, silt-sandy and mudstone rocks. Polymictic sandstones are oil-saturated to varying degrees; oil deposits are confined to them. To substantiate the quantitative criteria of the reservoir, the results obtained during special laboratory studies of the core were used. Filtration studies were carried out, where physical and hydrodynamic characteristics were determined when oil was displaced by displacing reagents. The obtained parameters were used to construct correlations collector non-collector. Using the relationships between the reservoir properties of the reservoir, the dependence of the porosity and permeability on the residual water content, as well as open porosity and permeability on the dynamic porosity, the boundary values were determined.

Review of Triassic insects in China

Studies of Triassic insects in China began in 1956, and so far, a total of 89 genera and 109 species have been found from the Triassic of China. The fossil records are from 17 provinces (or regions) in China are assigned to 11 orders except for two genera and species considered incertae sedis in Insecta. These Chinese Triassic insects including one Early Triassic, 53 Middle Triassic and 55 Late Triassic species are briefly reviewed in taxonomy and distribution, and listed here with detailed taxonomic and stratigraphic information. The Middle Triassic Tongchuan Entomofauna and Late Triassic Toksun Entomofauna are introduced much detailed from the perspectives of composition and taxonomy. Existing data indicate that the Chinese Triassic entomofauna is dominated by Hemiptera, Mecoptera and Coleoptera; the Chinese Early Triassic insects are only known from Fuyuan in Yunnan Province, Middle Triassic ones mainly known from northern China and sporadically from Guizhou Province, southern China, and Late Triassic ones widely seen in both northern and southern China; and the Middle and Late Triassic entomofaunas are similar in abundance but show a pattern of “more in northern China than in southern China”.