Spatiotemporal changes in fossil specimen completeness can bias our understanding of a group's evolutionary history. The quality of the sauropodomorph fossil record was assessed a decade ago, but the number of valid species has since increased by 60%, and 17% of the taxa from that study have since undergone taxonomic revision. Here, we assess how 10 years of additional research has changed our outlook on the group's fossil record. We quantified the completeness of all 307 sauropodomorph species currently considered valid using the skeletal completeness metric, which calculates the proportion of a complete skeleton preserved for each taxon. Taxonomic and stratigraphic age revisions, rather than new species, are the drivers of the most significant differences between the current results and those of the previous assessment. No statistical differences appeared when we use our new dataset to generate temporal completeness curves based solely on taxa known in 2009 or 1999. We now observe a severe drop in mean completeness values across the Jurassic–Cretaceous boundary that never recovers to pre‐Cretaceous levels. Explaining this pattern is difficult, as we find no convincing evidence that it is related to environmental preferences or body size changes. Instead, it might result from: (1) reduction of terrestrial fossil preservation space due to sea level rise; (2) ecological specificities and relatively high diagnosability of Cretaceous species; and/or (3) increased sampling of newly explored sites with many previously unknown taxa. Revisiting patterns in this manner allows us to test the longevity of conclusions made in previous quantitative studies.

中文翻译：

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十年的发现：重新审视蜥脚类恐龙的化石记录

化石标本完整性的时空变化可能会使我们对一个群体的进化史的理解产生偏差。sauropodomorph化石记录的质量在十年前进行了评估，但是此后有效物种的数量增加了60％，并且该研究中17％的分类单元已经进行了分类修订。在这里，我们评估了10年的额外研究如何改变了我们对该小组化石记录的看法。我们使用骨架完整性度量标准量化了当前被认为有效的所有307种鳞茎类目物种的完整性，该度量计算每个分类单元保存的完整骨架的比例。分类学和地层学年龄修订，而不是新物种，是当前结果与先前评估结果之间最显着差异的驱动因素。当我们仅使用2009年或1999年已知的分类单元使用新数据集生成时间完整性曲线时，没有统计差异。我们现在观察到侏罗纪-白垩纪边界的平均完整性值出现了严重下降，从未恢复到白垩纪前的水平。很难解释这种模式，因为我们没有令人信服的证据表明它与环境偏好或体重变化有关。相反，这可能是由于：（1）由于海平面上升而减少了陆地化石的保存空间；（2）白垩纪物种的生态特异性和较高的可诊断性；和/或（3）增加对许多以前未知的分类单元的新勘探站点的采样。以这种方式重新审视模式，使我们能够检验以前的定量研究得出的结论的寿命。