Kufner Aaron M, Deckman Max E, Miller Hannah R, So Calvin, Price Brandon R, Lovelace David M
Department of Geoscience, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
University of Wisconsin Geology Museum, Madison, Wisconsin, United States of America.
PLoS One. 2025 Apr 2;20(4):e0317325. doi: 10.1371/journal.pone.0317325. eCollection 2025.
Metoposaurid-dominated bonebeds are relatively commonplace in Upper Triassic continental deposits with at least ten monodominant, densely-packed bonebeds globally. The biostratinomy of several classic localities in India, North America, and Poland have been explored in detail; however, variability in methods and resultant conclusions point to the need for a more rigorous approach to understanding both the taphonomic and the ecological origins of metoposaurid-dominated bonebeds. Here we present the first monodominant metoposaurid mass mortality assemblage from the Late Triassic Popo Agie Formation and the stratigraphically lowest known record of several fauna from the Popo Agie Fm including the first occurrence of Buettnererpeton bakeri in Wyoming. We employ previously tested binning methods based on perceived hydrodynamic equivalence ("Voorhies groups") to assess pre-burial skeletal sorting. We suggest a simple counting and normalization method that avoids the inherent bias introduced by the interpretation of hydrodynamic equivalence of skeletal elements in taxa that lack actualistic experimental data. In contrast to other North American metoposaurid bonebeds, the sedimentology and skeletal sorting analyses of the Nobby Knob quarry support an autochthonous origin of this assemblage in a fluvio-lacustrine system with relatively little pre-burial sorting. Despite differences in underlying assumptions regarding the dispersal potential of specific skeletal elements, binning methods tend to follow similar trends regardless of framework used to assess different assemblages.
在晚三叠世大陆沉积物中，甲龙类主导的骨床相对常见，全球至少有十个单优势、密集堆积的骨床。印度、北美和波兰的几个经典地点的生物地层学已得到详细研究；然而，方法的差异和所得出的结论表明，需要一种更严谨的方法来理解甲龙类主导的骨床的埋藏学和生态起源。在此，我们展示了来自晚三叠世波波阿吉组的首个单优势甲龙类大规模死亡组合，以及波波阿吉组几种动物群在地层上已知的最低记录，包括怀俄明州首次出现的贝克氏布氏螈。我们采用基于感知水动力等效性（“沃尔希斯组”）的先前测试过的分类方法来评估埋藏前的骨骼分选情况。我们提出一种简单的计数和归一化方法，避免了在缺乏实际实验数据的分类群中，因解释骨骼元素的水动力等效性而引入的固有偏差。与北美其他甲龙类骨床不同，诺比诺布采石场的沉积学和骨骼分选分析支持了该组合在一个河流 - 湖泊系统中原地形成，且埋藏前分选相对较少。尽管在关于特定骨骼元素扩散潜力的潜在假设上存在差异，但无论用于评估不同组合的框架如何，分类方法往往遵循相似的趋势。
