Search results for "Late triassic"
showing 7 items of 7 documents
Mandible histology in Metoposaurus krasiejowensis (Temnospondyli, Stereospondyli) from the Upper Triassic of Poland
2021
Recent studies that have systematically augmented our knowledge of dermal bones of the Late Triassic temnospondyl amphibian Metoposaurus krasiejowensis have mostly focused on shoulder girdle elements and the skull. So far, histological data on the mandible are still scant. For the present study, two mandibles have been examined, using 50 standard thin sections. Dermal bones of the mandible reveal a uniform diploë structure, with the external cortex consisting of moderately vascularised, parallel-fibred bone, as well as a distinct alternation of thick zones and thinner annuli. Dense bundles of well-mineralised Sharpey’s fibres are seen in the external cortex over the entire length of the man…
Climatic influence on the growth pattern ofPanthasaurus maleriensisfrom the Late Triassic of India deduced from paleohistology
2020
Metoposaurids are representatives of the extinct amphibian clade Temnospondyli, found on almost every continent exclusively in the Late Triassic deposits. Osteohistologically, it is one of the best-known temnospondyl groups, analyzed with a wide spectrum of methods, such as morphology, morphometry, bone histology or computed modelling. The least known member of Metoposauridae isPanthasaurus maleriensisfrom the Pranhita-Godavari basin in Central India, being geographically the most southern record of this family. For the first time the bone histology of this taxon was studied with a focus on the intraspecific variability of the histological framework and the relationship between the observed…
Feeding biomechanics of Late Triassic metoposaurids (Amphibia: Temnospondyli): a 3D finite element analysis approach
2017
The Late Triassic freshwater ecosystems were occupied by different tetrapod groups including large-sized anamniotes, such as metoposaurids. Most members of this group of temnospondyls acquired gigantic sizes (up to 5 m long) with a nearly worldwide distribution. The paleoecology of metoposaurids is controversial; they have been historically considered passive, bottom-dwelling animals, waiting for prey on the bottom of rivers and lakes, or they have been suggested to be active mid-water feeders. The present study aims to expand upon the paleoecological interpretations of these animals using 3D finite element analyses (FEA). Skulls from two taxa, Metoposaurus krasiejowensis, a gigantic taxon …
Palaeohistology helps reveal taxonomic variability in exceptionally large temnospondyl humeri from the Upper Triassic of Krasiejów, SW Poland
2023
For more than twenty years, palaeontological excavations have been carried out at the Upper Triassic site of Krasiejów (south-west Poland), providing thousands of skeletal elements belonging to various tetrapod groups. However, almost all bones are preserved in a disarticulated state. This generates problems in taxonomic assignment among closely related groups, e.g., stereospondyl amphibians. As far as cranial elements, the pectoral girdle bones and the intercentra are very diagnostic, while all other remaining skeletal elements are difficult to unambiguously assign between either the capitosaurid Cyclotosaurus intermedius or the trematosaurid Metoposaurus krasiejowensis, both originating f…
Eucynodont teeth from the Late Triassic of Krasiejów, Southern Poland
2021
Recent discoveries of Mammaliamorph teeth in the Keuper of southern Poland have extended the global record of eucynodonts in the Late Triassic and revealed a significant diversity of the group at that time. Here,we expand on this record with the description of new cynodont postcanine teeth from the Krasiejów bone bed. They show the dental morphology typical for Dromatheriidae, with a single root and crown without cingulum. We assigned them to Polonodon woznikensis, described from Woźniki. None of the 38 teeth from Krasiejów and Woźniki exhibit signs of serious wear, potentially indicating a very fast rate of tooth replacement in Polonodon.
Tethyan magnetostratigraphy from Pizzo Mondello (Sicily) and correlation to the Late Triassic Newark astrochronological polarity time scale
2004
We present the magnetostratigraphy and stable isotope stratigraphy from an expanded (~430-m-thick) Upper Triassic marine limestone section at Pizzo Mondello, Sicily, and review published biostratigraphic information that can be used to defi ne the location of the conodont Carnian-Norian and Norian- Rhaetian boundaries in this section. Pizzo Mondello offers good potential for magnetostratigraphic correlation of marine biostratigraphic and chemostratigraphic data with the continental Newark astrochronological polarity time scale (APTS) for development of an integrated Late Triassic time scale. The relatively stable average values of 18O centered on 0‰ are a strong indication that the Cherty …
Aetosaur pes from the Upper Triassic of Krasiejów (Poland), with remarks on taxonomy of isolated bones
2021
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.