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Aetosaur pes from the Upper Triassic of Krasiejów (Poland), with remarks on taxonomy of isolated bones

Górnicki Szymon, Antczak Mateusz, Bodzioch Adam

Annales Societatis Geologorum Poloniae

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2021

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Vol. 91, No. 4

389--396

EN

The incomplete, articulated, right pes of an aetosaur, extracted from the lower bone-bearing horizon of the Krasiejów Late Triassic site, is larger than any other, known from among the Aetosauria. Its individual bones resemble those of at least three genera: Desmatosuchus (astragalus), Typothorax (ungual phalanges), and Stagonolepis (metatarsals). This underscores the highly speculative nature of the taxonomical classification of isolated postcranial bones and makes it impossible to assign the limb to any particular genus. The phalangeal formula is 2-3-4-5-?; for the fifth finger: 2/3/4 is possible. The anatomy of the pes indicates adaptation for digging.

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Age and correlation of Late Triassic tetrapods from southern Poland

Lucas S. G.

Annales Societatis Geologorum Poloniae

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2015

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Vol. 85, No. 4

627--635

EN

Age assignments of Triassic tetrapod fossils can be achieved by direct reference to a scheme of Triassic land-vertebrate faunachrons (LVFs) that correlates Triassic tetrapod fossil assemblages to each other based solely on the tetrapod fossils. Correlation of Triassic tetrapod assemblages to the standard global chronostratigraphic scale (SGCS, the “marine timescale”) is a separate cross correlation between the vertebrate biochronology and marine biochronology that usually relies on other data (e. g., palynostratigraphy, magnetostratigraphy, radioisotopic ages) to be completed. Late Triassic tetrapod fossils in southern Poland are found at two stratigraphic positions, the Krasiejów and Lisowice levels. The tetrapod assemblage of the Krasiejów level is assigned to the early Adamanian LVF based primarily on the stratigraphic overlap of the phytosaur Parasuchus with the Adamanian index aetosaur Stagonolepis. The amphibians Cyclotosaurus and Gerrothorax, a Proterochersis-like turtle and the aetosaur Paratypothorax from the Lisowice level indicate it is assignable to the Revueltian LVF. Cross correlations to the SGCS are less definitive, but suggest that the Krasiejów level is late Carnian and the Lisowice level is early/middle Norian. However, this correlation of the Krasiejów level is confounded by disagreements over correlation of the marine Carnian–Norian boundary to nonmarine strata. Indeed, the possibility that the Krasiejów tetrapods fill a gap in the early Norian record of tetrapods merits consideration. Such difficulties emphasize the value of correlating tetrapod assemblages to each other using a land-vertebrate biostratigraphy/biochronology, instead of immediately attempting the more problematic correlation to the SGCS.

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Late Ladinian radiolarians from the Tahtalidag Nappe of the Antalya nappes, SW Turkey : remarks on the late Middle and Late Triassic evolution of the Tahtalidag Nappe

Tekin U., Sonmez I.

Acta Geologica Polonica

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2010

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Vol. 60, no. 2

199-217

EN

The late Ladinian to Late Triassic succession of the Tahtalidag (upper) Nappe of the Antalya nappes was studied in the Egregindere section, north of the city of Antalya, SW Turkey. The chert bands in the central part of the section have yielded poorly to moderately preserved radiolarians documenting the Late Ladinian Muelleritortis firma and Muelleritortis cochleata radiolarian zones. Based on the Egregindere succession, a major deepening event, evidenced by radiolarian cherts, took place between the middle and late Late Ladinian. The Late Triassic thick-bedded neritic limestones represent a shallowing-upward sequence, which formed as a result of the horst-like rising of the Tahtalidag Nappe during the Late Triassic block faulting. Fifty-nine radiolarian taxa have been determined from the Upper Ladinian of the Egregindere section. One species (Muelleritortis elegans) and two subspecies (Muelleritortis firma equispinosa and Muelleritortis firma globosa) are described as new.

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Evidence for a very low-energy fluvial system: a case study from the dinosaur-bearing Upper Triassic rocks of Southern Poland

Gruszka B., Zieliński T.

Geological Quarterly

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2008

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Vol. 52, No 3

239-239

EN

The Upper Triassic succession in S Poland in which dinosaur bones have been found consists predominantly of siltstones and claystones. Three units are distinguished. The lower most and the upper most units reflect an alluvial environment, whereas the middle one represents lacustrine facies. The lower alluvial unit is interpreted as a record of ephemeral, sinuous, suspended-load channels with rapid vertical accretion. Channel barforms are lack ing. The environmentis interpreted as a low-en ergy anastomosing fluvial system. The clayey middle unit is interpreted as having formed in a wide long-lived lake. The top of the lacustrine deposits shows signs of vertisol-type pedogenesis, most probably under subtropical conditions, with seasonally-inuced wet and dry intervals. The upper unit reflects a low-energy meander ingriver system. Silty point bars were abundant and the channels migrated freely. The energy level of this fluvial system was slightly higher than that of the earlier one, which is interpreted as an effect of base-level lowering in combination with an increasingly humid climate. The al most exclusively silty/clayey alluvial deposits represent an exceptionally rare facies. The drainage basin must have been an extremely flat lowland. The presence of vertebrate bones within the anastomosing and meandering river deposits indicates that low-en - ergy alluvial plains were apparently favourable habitats for both reptiles and amphibians during the Late Triassic: under the subtropical, seasonally dry conditions, the animals must have preferred moist lowareas, i.e. the flood basins and abandoned channels on the flat valley floors.