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Microstructural characteristics and seasonal growth patterns observed in Metoposaurus krasiejowensis teeth
Geological Quarterly ( IF 0.9 ) Pub Date : 2022-11-14 , DOI: 10.7306/gq.1658
Łukasz Weryński , Mariusz Kędzierski

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.



中文翻译:

在 Metoposaurus krasiejowensis 牙齿中观察到的显微结构特征和季节性生长模式

红斑甲龙的牙齿微观结构研究观察外部形态、内部微观结构(包括牙本质结构和定向孔隙率作为可能的掠夺性适应)和牙釉质/牙釉质矿物成分。扫描电子显微镜 (SEM) 观察和光学显微镜薄片检查使我们能够识别牙齿横截面中的定向孔隙率,此处将其解释为由 temnospondyls 和相关组显示的迷宫齿结构的一部分。这个运河网络非常复杂,呈现出三维结构。根据距尖端的距离,牙齿呈现出不同的横截面,具有宽的、圆形的、加固的基部和横向压缩的、带切削刃的定向尖牙截面。有趣的是,在M. krasiejowensis中观察到的内部结构牙齿表现出 temnospondyl 牙齿内部结构的奇特变化,因为回旋状的运河状结构似乎不规则并出现在牙齿的上部,而牙齿基部则显示出规则的结构,牙髓腔周围有气孔。此外,观察到被解释为 Andresen 线的增量生长标记带,其特征是明显的颜色变化,对牙本质的季节性生长模式具有强烈的影响。此外,通过扫描电子显微镜-能量色散光谱 (SEM-EDS) 点和映射分析,观察到很大比例 (1.43–2.73%) 的氟化物作为牙釉质的成分,表明牙釉质的氟磷灰石矿物学。

更新日期:2022-11-16
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