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Microstructural characteristics and seasonal growth patterns observed in Metoposaurus krasiejowensis teeth

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Weryński Ł. , Kędzierski M.

2022

tom Vol. 66, No. 3

art. no. 26

The tooth microstructure of Metoposaurus krasiejowensis was studied to observe external morphology, internal microstructure (comprising dentine structure and directional porosity as possible predatory adaptations) and enamel/enameloid mineral composition. Scanning electron microscopy (SEM) observation and thin-section inspection by light microscope enabled us to recognize a directional porosity in the tooth cross-sections, interpreted here as a part of the labyrinthodont structure displayed by temnospondyls and related groups. This network of canals is highly complicated and reveals a three-dimensional structure. The teeth present different cross-sections based on the distance from the tip, with a wide, circular, reinforced base and lateral compressed, directional cuspidal section with cutting edge. Interestingly, the internal structure observed in M. krasiejowensis teeth exhibit a peculiar variation of internal structure of temnospondyl teeth, as the convoluted canal-like structure seems to be irregular and appears in the upper section of teeth, while teeth bases show a regular structure with a pulpal cavity circled by pores. Furthermore, bands of incremental growth marks interpreted as Andresen lines, characterized by pronounced colour variation, were observed with strong implications for seasonal growth patterns in dentine. Additionally, a significant proportion (1.43–2.73%) of fluoride was observed as a component of enamel by scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) point and mapping analyses, suggesting a fluorapatite mineralogy of enamel.

Summary of a decade of research at the Owadów–Brzezinki Lagerstätte (Tithonian, central Poland): A review and perspectives for the future

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Błażejowski B. , Weryński Ł. , Wierzbowski A. , Michalska M. , Hryniewicz K. , Uchman A. , Kugler S. , Bącal P. , Hołda-Michalska A.

2023

tom Vol. 21

83--98

For over ten years, the Lower to Upper Tithonian boundary beds cropping out in the Owadów–Brzezinki quarry have yielded numerous fossils of ammonites, bivalves, brachiopods, xiphosurans, decapods, insects, and vertebrates – including actinopterygian fishes and various reptiles and others, all of which exhibit fine preservation of their anatomical details due to special environmental conditions during their fossilization. The Owadów–Brzezinki section is also important for stratigraphical correlations because it contains ammonite faunas indicative of the NE European and NW European Subboreal zonal schemes, as well as Tethyan calpionellids. The whole faunal as- semblage, which represents taxa of many iconic groups of Mesozoic animals, has created the opportunity to establish the ‘Owadów– Brzezinki geopark’, a geoeducation area where the public, and especially the young, can learn about the beauty of the natural history of the region.