Although lags of bones and teeth are commonly cited criteria for marine unconformities, the consistency of the association of vertebrate fossils and discontinuity surfaces, as well as the taphonomic (postmortem) controls on this relationship, are poorly understood. A field test across fluvial, paralic, and shallow marine facies in the Campanian Two Medicine and Judith River formations of Montana indicates that the distribution of vertebrate skeletal concentrations is poorly correlated with the inferred durations of erosional and omissional hiatuses. Instead, vertebrate concentrations associated with discontinuities of all durations tend to be patchy and closely track the abundance of fossil material in underlying and lateral facies. Based on the analysis of 83 measured sections, we found first that erosional bases of channels and minor scours within channels yield vertebrate lags; tidally influenced fluvial deposits are more productive than are “upland” fluvial deposits. Second, erosional shoreface ravinements and their correlative transgressive marine flooding surfaces (fourth‐order sequence boundaries) have well‐developed vertebrate lags only along segments that cut across older shoreface deposits. Third, a nonerosional, widely traceable discontinuity, which is interpreted as the nonmarine extension of a 75.4‐Ma third‐order transgressive surface, is completely lacking in vertebrate concentrations. Despite being unfossiliferous itself, this discontinuity does mark a regional change in the richness of the vertebrate fossil record, with overlying beds characterized by a much greater abundance of skeletal material. Fourth, a laterally extensive set of erosional surfaces, embedded within multistory fluvial sandstone sheets, is the nonmarine extension of an 80‐Ma third‐order sequence boundary in the marine basin and lacks vertebrate concentrations. The strong dependence of vertebrate lag development on preexisting local sources of skeletal material rather than on the magnitude of the erosional vacuity or the duration of the hiatus contrasts with skeletal concentrations of invertebrates in marine successions, where exhumation is generally much less important than the production of new elements during the hiatus. These findings provide a guide to prospecting productive fossil horizons in terrestrial records and underscore fundamental differences in the ways in which bioclastic material accumulates in terrestrial and shallow marine settings, the qualities of paleobiologic data derived from such concentrations, and the relative reliabilities of skeletal material as cues to stratigraphically significant discontinuities.

中文翻译：

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陆地和浅海记录中脊椎动物骨骼浓度和不连续面的关联：蒙大拿州白垩纪的测试

虽然骨骼和牙齿的滞后是海洋不整合的常用标准，但对脊椎动物化石和不连续表面关联的一致性以及对这种关系的埋藏（尸检）控制知之甚少。对蒙大拿州 Campanian Two Medicine 和 Judith River 地层的河流、近海和浅海相进行的实地测试表明，脊椎动物骨骼浓度的分布与推测的侵蚀和遗漏中断持续时间的相关性很差。相反，与所有持续时间的不连续性相关的脊椎动物浓度往往是不完整的，并密切跟踪下伏和侧相中化石材料的丰度。根据对 83 个实测断面的分析，我们首先发现通道的侵蚀基部和通道内的轻微冲刷产生脊椎动物滞后；受潮汐影响的河流沉积物比“高地”河流沉积物的生产力更高。其次，侵蚀性岸面沟壑及其相关的海进海侵面（四阶层序边界）仅沿着穿过较旧岸面沉积物的部分具有发育良好的脊椎动物滞后。第三，一种非侵蚀性的、可广泛追踪的不连续性，被解释为 75.4 Ma 三阶海侵表面的非海相延伸，完全缺乏脊椎动物浓度。尽管本身没有化石，但这种不连续性确实标志着脊椎动物化石记录丰富性的区域变化，上覆层以更丰富的骨骼材料为特征。第四，一组横向广泛的侵蚀面，嵌入多层河流砂岩片中，是海盆中 80-Ma 三阶层序边界的非海相延伸，缺乏脊椎动物。脊椎动物滞后发育强烈依赖于预先存在的局部骨骼物质来源，而不是侵蚀真空的大小或中断的持续时间，这与海洋演替中无脊椎动物的骨骼浓度形成鲜明对比，在海洋演替中，挖掘通常远不如产生骨骼物质重要。中断期间的新元素。这些发现为在陆地记录中勘探生产性化石层提供了指导，并强调了生物碎屑材料在陆地和浅海环境中积累方式的根本差异，