6533b85cfe1ef96bd12bc911

RESEARCH PRODUCT

Long bone histology of Metoposaurus diagnosticus (Temnospondyli) from the Late Triassic of Krasiejów (Poland) and its paleobiological implications

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ABSTRACT Long bones of the temnospondyl Metoposaurus diagnosticus krasiejowensis from the Late Triassic of Krasiejow, Poland, were studied using histological analysis. Six femora, three humeri, a radius, and an ulna were prepared for thin-sectioning. In all bones, the dominant type of primary bone matrix is parallel-fibered bone with secondary, or rarely primary, deposition of lamellar bone inside vascular canals. Two small humeri and the smallest femur showed incipient fibrolamellar bone, which may be a character typical for juvenile individuals. The medullary region is filled with well-developed trabecular bone. The growth marks in all bones are organized as thick layers of highly vascularized zones and thick compact annuli with numerous rest lines, which may correspond with favorably wet and long, unfavorably dry seasons. The thickness of the annuli is similar to the thickness of zones for reasons still unknown. Based on the highest estimated number of growth cycles in the femora, the long bones from K...