Clark James W, Donoghue Philip C J
Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath BA2 7AY, UK.
Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, Bristol BS8 1TQ, UK.
R Soc Open Sci. 2025 May 28;12(5):242158. doi: 10.1098/rsos.242158. eCollection 2025 May.
The timing of the origin of crown-angiosperms exemplifies the impact of competing approaches to establishing evolutionary timescales. Fossils of unequivocal crown-angiosperms are not known from before the Cretaceous, and yet molecular estimates range from the Late Jurassic to the Permian. We show that the disagreement between molecular and palaeobotanical estimates is an artefact of interpretations of the fossil record. We employ relaxed molecular clock methods that reflect competing interpretations of the fossil record to show that such methods are entirely capable of recovering an explosive diversification of angiosperms if the fossil record can be interpreted confidently to support this. We argue that older putative angiosperm records have insufficient claim on crown-angiosperm affinity to justify their use in divergence time estimation and, in their absence, estimate crown-angiosperms to have diverged in a Late Jurassic-Early Cretaceous interval. This diminishes the Jurassic gap between molecular clock estimates and literal interpretations of the fossil record but expands the Jurassic gap in the fossil record of stem-angiosperms that is not readily rationalized. Attention should be refocused on the history of stem-angiosperms in which the body plan of this most successful lineage of land plants was assembled.
冠层被子植物起源的时间体现了建立进化时间尺度的不同方法所产生的影响。确凿的冠层被子植物化石在白垩纪之前并不为人所知,然而分子估计的时间范围从晚侏罗世到二叠纪。我们表明,分子估计与古植物学估计之间的分歧是对化石记录解释的人为产物。我们采用反映对化石记录不同解释的宽松分子钟方法,以表明如果化石记录能够被可靠地解释以支持这一点,那么这些方法完全能够揭示被子植物的爆发式多样化。我们认为,早期假定的被子植物记录对冠层被子植物亲缘关系的主张不足,无法证明其在分歧时间估计中的使用合理性,并且在缺乏此类记录的情况下,估计冠层被子植物在晚侏罗世 - 早白垩世期间发生了分歧。这缩小了分子钟估计与化石记录字面解释之间的侏罗纪差距,但扩大了难以合理解释的基部被子植物化石记录中的侏罗纪差距。注意力应重新聚焦于基部被子植物的历史,在这段历史中,这种陆地植物最成功谱系的身体结构得以形成。