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首页> 外文期刊>Palaios: An International Journal of the Society of Economic Paleontologists & Mineralogists >Genus-level taphonomic variation within cladid crinoids from the upper Pennsylvanian barnsdall formation, Northeastern Oklahoma
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Genus-level taphonomic variation within cladid crinoids from the upper Pennsylvanian barnsdall formation, Northeastern Oklahoma

机译：俄克拉荷马州东北部宾夕法尼亚州上巴恩斯达尔构造的包层海百合类内的属水平成因变异

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Previous comparative taphonomic studies have convincingly demonstrated that the taphonomic state of crinoid fossils is controlled largely by paleoenvironmental processes and constructional morphology. While taphonomic variability among depositional facies has a long history of investigation, the degree to which preservational heterogeneity is controlled by crinoid morphology has only recently been addressed and only at relatively coarse levels. Most studies to date have focused on taphonomic variability at the subclass or ordinal level, with little documentation of lower level taphonomic variation within a single crinoid subclass. A remarkably diverse, abundant, and well-preserved crinoid fauna, recovered from a single mudstone interval within the Upper Pennsylvanian (Missourian) Barnsdall Formation in northeastern Oklahoma, midcontinent North America, provides a unique opportunity to examine taphonomic trends among poteriocrine cladid crinoids at refined taxonomic levels. Genus-level variations in specimen completeness, axis of compaction, arm position, and features attributed to decay and scavenging are observed within this assemblage and taphonomic trends related primarily to the size of individuals are detected. These results indicate that taphonomic variability extends at least to genus level within the subclass Cladida. Understanding this variability is important in interpreting the genesis and nature of crinoid-bearing units, as minor variations in morphology, ethology, and scavenger preferences impart unexpected biostratinomic heterogeneity to Copan crinoid fauna that would otherwise be difficult to explain. Taphonomic variability at low taxonomic levels and the influence of preferential scavenging should be accounted for in future crinoid taphonomic grade studies, particularly in Pennsylvanian and younger deposits, in order to avoid taphonomic assumptions that may be overly broad.
机译：以前的比较性研究已令人信服地证明，海百合类化石的种姓状态在很大程度上受古环境过程和构造形态的控制。尽管沉积相之间的形态学变异性已有很长的研究历史，但直到最近才解决了由海百合形形态控制保存异质性的程度，并且仅在相对较粗糙的水平上进行了研究。迄今为止，大多数研究都集中在子类或序数级别的同位异义性上，很少有文献记载单个单齿状亚类中较低水平的同位异义性。从北美中部奥克拉荷马州东北俄克拉荷马州上宾夕法尼亚州（密苏里州）Barnsdall组中的单个泥岩层中发现的一种极其多样，丰富且保存完好的海百合类动物，为研究精制的斜角类海藻类海百合中的趋向性趋势提供了独特的机会。分类水平。在这种组合中观察到了样品完整性，压实轴，臂位置以及归因于腐烂和清除的特征的属水平变化，并且检测到主要与个体大小有关的自相趋势。这些结果表明，在Cladida子类中，拓朴变异性至少扩展到属水平。理解这种变异性对于解释含海百合的单位的起源和性质非常重要，因为形态，行为学和清除剂偏好的微小变化会给科潘海百合的动物群带来意想不到的生物地层学异质性，否则很难解释。为了避免可能的过分假设，在将来的海百合类塔状分级研究中，应考虑低分类学水平下的塔式变异性和优先清除的影响。

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