Fossil Leaves and Fruits of Cercis L. (Leguminosae) from the Eocene of Western North America
Fossil Leaves and Fruits of Cercis L. (Leguminosae) from the Eocene of Western North America
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DOI：
10.1086/675693
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发表时间：
2014-04
影响因子：
2.3
通讯作者：
Hui Jia;S. Manchester
中科院分区：
文献类型：
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作者：
Hui Jia;S. Manchester
研究的前提。需要更详细地了解Cercis L.的化石记录，以此作为重建进化的基础，以了解Caesalpinoideae的辐射。根据俄勒冈州和科罗拉多州的化石水果和树叶，该属现在可以追溯到北美西部的始新世晚期。关键成果。我们在俄勒冈州Teater Road(∼36 Ma)发现了一个新发现的Cercis叶子化石，它与先前在科罗拉多州弗洛里森特(∼34 Ma)发现的Cercis parvifolia Lesqueux物种一致。红叶紫荆的伴生角果。N.代表了Cercis最早被证实的化石果实。在它们不裂的豆荚中，一边有翼状凸缘，这些化石对应于Cercis的主要支系，而不是在系统发育上截然不同的现存物种Cercis chingii。回顾我们从文献中接受的其他事件，我们发现该属在中新世时在北半球广泛存在，尽管一些早期的古植物学报告必须被拒绝。结论。化石记录表明，Cercis是在始新世晚期建立的，到中新世已在北半球广泛分布。始新世晚期记录的叶片形状与中生生境一致，但叶大小相对较小，可能表明对干燥条件的适应。
Premise of research. The fossil record of Cercis L. needs to be understood in better detail as a basis for reconstructing the evolution for understanding the radiation of Caesalpinoideae. The genus can now be traced back to the late Eocene of western North America on the basis of fossil fruits and foliage from Oregon and Colorado. Pivotal results. We present a new occurrence of Cercis leaf fossils from Teater Road, Oregon (∼36 Ma), that conforms to the species Cercis parvifolia Lesquereux, previously recognized from Florissant, Colorado (∼34 Ma). Associated pods of Cercis herbmeyeri sp. n. represent the earliest confirmed fossil fruits of Cercis. In their indehiscent pods with a winglike flange along one margin, the fossils correspond to the main clade of Cercis rather than to the phylogenetically distinct extant species Cercis chingii. A review of other occurrences that we accept from the literature reveals that the genus was widespread in the Northern Hemisphere by the Miocene, although some earlier paleobotanical reports must be rejected. Conclusions. The fossil record indicates that Cercis was established by the late Eocene and had become widespread in the Northern Hemisphere by the Miocene. The late Eocene records have a lamina shape consistent with a mesic habitat but relatively small leaf size, which might indicate adaptation for drying conditions.