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Pelvic girdle morphology in Stagonolepis, with remarks on aetosaur systematics

Desmet Hilde G. B., Antczak Mateusz, Bodzioch Adam

Annales Societatis Geologorum Poloniae

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2022

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Vol. 92, No. 3

253--275

EN

In recent years, the Upper Triassic deposits at Krasiejów (south-west Poland) have yielded several tetrapod taxa, both aquatic and terrestrial. Stagonolepis olenkae is one of the terrestrial vertebrates recovered there; a quadrupedal, armoured aetosaur, which belonged to the crocodile-line archosaurs with a characteristic shovel-shaped snout. Several previous studies (osteological, histological and taphonomic) have attempted to understand the mode of life, growth pattern and possible dimorphism of this species and on this basis, to interpret palaeoecological, palaeoclimatic and stratigraphical implications. So far, the pelvic girdle of S. olenkae from Krasiejów remained undescribed. Here, the authors record stagonolepid ilia and pubes and a single ischium from collections housed at the University of Opole, and compare these with the pelvic girdles of other aetosaurian taxa. These well-preserved bones have a typical aetosaurian general outline, but also show some peculiar features. For instance, the preacetabular blade of the ilium is short and flattened and does not exceed the pubic peduncle; several small foramina occur dorsally of the supracetabular crest; the number of pubic foramina is two and the pubic symphysis is less than half the length of the pubis. The material is similar to previously known Stagonolepis robertsoni from the Elgin area, except for the length of the symphysis. The bones presented here differ between each other in thickness, morphology of the preacetabular blade or attachment of sacral ribs, which may be connected with sexual dimorphism. The pelvic girdle of most aetosaurs is not well known. This is unfortunate, because it is an important element in the study of the evolution of the pelvic girdle and in phylogenetic analyses. Thus, the ilia, pubes and ischium of the present study are valuable examples that may contribute to the discussion of the ontogeny and sexual dimorphism in Stagonolepis, as well as to our general knowledge of the Aetosauria.

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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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Preliminary report on the microvertebrate faunal remains from the Late Triassic locality at Krasiejów, SW Poland

Kowalski Jakub, Bodzioch Adam, Janecki Piotr A., Ruciński Maciej R., Antczak Mateusz

Annales Societatis Geologorum Poloniae

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2019

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Vol. 89, No. 3

291--305

EN

Fossil vertebrate remains from the Keuper unit in the vicinity of the village of Krasiejów have been analyzed for almost two decades. However, the main goal of these works was focused mainly on large vertebrates. Here the authors present the first description of microvertebrate fossils from that site. The collection of around 5,000 specimens is mainly comprised of teeth and scales. The most numerous remains belong to osteichthyans: dipnoans (Ptychoceratodus and cf. Arganodus), palaeoniscids, semionotids, redfieldiids and chondrichthyans, such as Lonchidion sp., which is the first indisputable record of that genus in the Upper Triassic of Poland and the first shark at the Krasiejów locality. Tetrapod fossils consist of temnospondyl amphibians, rhynchocephalian lepidosauromorphs and archosauromorphs. Among them, temnospondyl amphibian remains are the most numerous and are represented mostly by Metoposaurus. However, on the basis of diversity in tooth morphotypes, the occurrence of other taxa cannot be excluded. Rhynchocephalians are composed of 7 fragmentary jaw morphotypes with dentition, which could indicate high taxonomic diversity (cf. Planocephalosaurus, cf. Diphydontosaurus and cf. Clevosaurus). The most varied fossil group was assigned to the archosauromorphs. The authors can distinguish at least 19 teeth morphotypes, which show similarities to the dentition of: protorosaurians (cf. Tanystropheidae), pseudosuchians (cf. Protecovasaurus, cf. Revueltosaurus), early crocodylomorphs and basal sauropodomorph dinosaurs. The first occurrence of a theropod dinosaur and cynodonts at the Krasiejów locality is also recorded. However, their remains are very rare. These new records show a high taxonomic diversity at the Krasiejów locality that contributes to our deeper understanding of Late Triassic ecosystem of Poland.

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Calcite pseudomorphs after evaporates from the Muschelkalk (Middle Triassic) of the Holy Cross Mountains (Poland)

Bodzioch Adam

Geologos

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2003

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Vol. 6

169--180

EN

Pseudomorphs after sulphate minerals, together with accompanying phenomena, are the only evidence of evaporites in the Muschelkalk of the Holy Cross Mts. They appear as geodes or full-filled nodules built of coarse-crystalline calcite, and their after-evaporite origin have been interpreted on the ground of lithological, petrographical and geochemical characteristics. Evaporitic conditions of sedimentation are indicated mainly by remnants of sulphate minerals occurring commonly in the geodes, and by remnants of dolomite in the host rocks. Dissolution of sulphates, evidenced by collapse breccias, pseudomorphs, and pervasive calcitization of the geodes-bearing horizons, took place in consequence of fresh water influx, which is suggested by elemental and isotopic data.