Data from: Preservation is predictable: quantifying the effect of taphonomic biases on ecological disparity in birds

Evolutionary inferences from fossil data often require accurately reconstructing differences in richness and morphological disparity between fossil sites across space and time. Biases such as sampling and rock availability are commonly accounted for in large-scale studies; however, preservation bias is usually dealt with only in smaller, more focused studies. Birds represent a diverse, but taphonomically fragile, group commonly used to infer environmental conditions in recent (Pleistocene and later) fossil assemblages, and their relative scarcity in the fossil record has led to controversy over the timing of their radiation. Here, I use simulations to show how even weak taphonomic biases can distort estimates of richness, and render variance sensitive to sample size. I then apply an ecology-based filtering model to recent bird assemblages to quantify the distortion induced by taphonomy. Certain deposit types, such as caves, show less evidence of taphonomic distortion than others, such as fluvial and lacustrine deposits. Archaeological middens unsurprisingly show some of the strongest evidence for taphonomic bias, and they should be avoided when reconstructing Pleistocene and early Holocene environments. Further, these results support previously suggested methods for detecting fossil assemblages that are relatively faithfully preserved (e.g., presence of difficult-to-preserve taxa), and I use these results to recommend that future large-scale studies include facies diversity along with metrics such as rock volume, or compare only sites with similar taphonomic histories.基于化石数据开展的演化推演，往往需要精准重建不同时空维度下各化石点间的类群丰富度与形态分异度（morphological disparity）差异。在大规模研究中，采样偏差与岩石可获取性偏差等干扰因素通常已得到充分校正与控制；然而，保存偏差（preservation bias）的处理往往仅见于规模更小、针对性更强的专项研究中。 鸟类是一类类群多样但埋藏学上易受破坏的类群，常被用于推断更新世（Pleistocene）及更晚近的化石组合的环境条件；而其在化石记录中的相对稀缺性，引发了学界关于鸟类演化辐射时间节点的争议。 本研究通过模拟实验证实，即便是微弱的埋藏偏差（taphonomic bias）也会扭曲类群丰富度的估算结果，并使方差对样本量产生敏感响应。随后，本研究将基于生态学的过滤模型应用于晚近鸟类化石组合，以量化埋藏作用（taphonomy）所引发的失真程度。 部分沉积类型（如洞穴堆积）相较于河流相（fluvial）、湖相（lacustrine）沉积等类型，埋藏失真的迹象更为微弱。考古贝冢（archaeological midden）无疑是埋藏偏差证据最为显著的沉积类型之一，在重建更新世与全新世早期（early Holocene）的古环境时，应避免采用此类堆积。 此外，本研究结果支持此前提出的识别保存状态相对完好的化石组合的方法（例如，检测难以保存的类群是否存在）；基于上述结论，本研究建议未来的大规模研究应纳入岩相多样性（facies diversity）与岩石体积等度量指标，或仅对埋藏历史相近的化石点开展对比分析。