Data from: Deep time diversity of metatherian mammals: implications for evolutionary history and fossil-record quality

Despite a global fossil record, Metatheria are now largely restricted to Australasia and South America. Most metatherian palaeodiversity studies to date are limited to particular subclades, time intervals and/or regions, and few consider uneven sampling. Here, we present a comprehensive new dataset on metatherian fossil occurrences (Barremian to end-Pliocene). These data are analysed using standard rarefaction and Share-holder Quorum Subsampling (including a new protocol for handling ‘Lagerstätten’-like localities). Global metatherian diversity was lowest during the Cretaceous, and increased sharply in the Paleocene, where the South American record begins. Global and South American diversity rose in the early Eocene then fell in the late Eocene, contrasting the North American pattern. In the Oligocene diversity declined in the Americas but this was more than offset by Oligocene radiations in Australia. Diversity continued to decrease in Laurasia with final representatives in North America (excluding the later entry of Didelphis virginiana) and Europe in the early Miocene, and Asia in the middle Miocene. Global metatherian diversity appears to have peaked in the early Miocene, especially in Australia. Following a trough in the late Miocene, the Pliocene saw another increase in global diversity. By this time, metatherian biogeographic distribution had essentially contracted to that of today. Comparison of the raw and sampling-corrected diversity estimates, coupled with evaluation of ‘coverage’ and number of prolific sites, demonstrates that the metatherian fossil record is spatially and temporally extremely patchy. Therefore, assessments of macroevolutionary patterns based on the raw fossil record (as in most previous studies) are inadvisable.尽管后兽下纲（Metatheria）拥有全球范围的化石记录，但现生类群目前仅局限于澳大拉西亚与南美洲。迄今为止，绝大多数后兽类古生物多样性研究仅针对特定亚支、时间区间或区域展开，且极少考虑采样不均衡的问题。本文首次发布一套涵盖后兽类化石产出记录的综合全新数据集，时间跨度从巴列姆期（Barremian）至上新世末期。本研究采用标准稀疏法与股东配额重采样法（Share-holder Quorum Subsampling，包含一套处理特异埋藏化石库（Lagerstätten）类遗址的全新方案）对上述数据进行分析。 全球后兽类多样性在白垩纪达到最低值，并在古新世出现显著跃升——这一时期南美洲的后兽类化石记录首次被发现。全球及南美洲的后兽类多样性在始新世早期上升，随后在始新世晚期下降，这与北美地区的多样性变化模式截然相反。渐新世时期，美洲地区的后兽类多样性有所下滑，但澳大利亚在该时期的辐射演化远超弥补了这一损失。劳亚大陆的后兽类多样性持续走低：北美地区（不含后续迁入的弗吉尼亚负鼠（Didelphis virginiana））与欧洲的最后一批化石代表出现于中新世早期，亚洲的最后代表则见于中新世中期。全球后兽类多样性的峰值大致出现在中新世早期，其中澳大利亚地区的多样性跃升最为显著。晚中新世经历一次多样性低谷后，上新世时期全球后兽类多样性再度回升。至此时段，后兽类的生物地理分布已基本收缩至现今的分布范围。 通过对比原始多样性估计值与经采样校正后的多样性估计值，并结合对采样覆盖度与高产遗址数量的评估，结果显示后兽类的化石记录在空间与时间尺度上均存在极强的碎片化特征。因此，基于原始化石记录开展的宏观演化模式评估（如绝大多数既往研究）并不恰当。