Eocene Araucaria Sect. Eutacta from Patagonia and floristic turnover during the initial isolation of South America
Eocene Araucaria Sect. Eutacta from Patagonia and floristic turnover during the initial isolation of South America
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DOI：
10.1002/ajb2.1467
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发表时间：
2020-05-09
影响因子：
3
通讯作者：
Andruchow-Colombo, Ana
中科院分区：
文献类型：
--
作者：
Rossetto-Harris, Gabriella;Wilf, Peter;Andruchow-Colombo, Ana
巴塔哥尼亚的前始新世植物群记录了冈瓦纳最终分离的生物反应。南洋杉属（Araucaria）是一种分布于世界各地的针叶树属，在中生代时分布于南美洲和澳大拉西亚之间。化石分配到澳大利亚南洋杉组Eutacta通常是由孤立的器官，使诊断困难。南洋杉Berry产于始新世中期阿根廷巴塔哥尼亚的Rio Pichileufu（RP）遗址，最初被归入Eutacta组，后来在始新世早期的拉古纳德尔洪科（LH）地区被报道。然而，A. pichileufensis与Sect.Eutacta的同源性以及南洋杉属材料在巴塔哥尼亚植物区系中的同源性尚未用现代方法进行过检验。pichileufensis旁边的大型（n = 192）新的化石收集南洋杉LH和RP，包括多器官保存的叶状枝，胚珠复合体，和花粉锥。结果在LH中描述了南洋杉Araucaria huncoensis sp. nov.，在RP中改进了南洋杉Araucaria pichileufensis的全植物概念。这两个物种分别解决在冠和茎的组。Eutacta.Conclusions我们的研究结果证实的存在，并表明在南美洲的组。Eutacta在南极分离早期的生存。这些异常完整的化石明显早于冠层真核生物的几个分子年龄估计。两种南洋杉的分化表明针叶树周转在气候变化和最初的南美隔离从早到中始新世。
Premise Eocene floras of Patagonia document biotic response to the final separation of Gondwana. The conifer genus Araucaria, distributed worldwide during the Mesozoic, has a disjunct extant distribution between South America and Australasia. Fossils assigned to Australasian Araucaria Sect. Eutacta usually are represented by isolated organs, making diagnosis difficult. Araucaria pichileufensis E.W. Berry, from the middle Eocene Rio Pichileufu (RP) site in Argentine Patagonia, was originally placed in Sect. Eutacta and later reported from the early Eocene Laguna del Hunco (LH) locality. However, the relationship of A. pichileufensis to Sect. Eutacta and the conspecificity of the Araucaria material among these Patagonian floras have not been tested using modern methods.Methods We review the type material of A. pichileufensis alongside large (n = 192) new fossil collections of Araucaria from LH and RP, including multi-organ preservation of leafy branches, ovuliferous complexes, and pollen cones. We use a total evidence phylogenetic analysis to analyze relationships of the fossils to Sect. Eutacta.Results We describe Araucaria huncoensis sp. nov. from LH and improve the whole-plant concept for Araucaria pichileufensis from RP. The two species respectively resolve in the crown and stem of Sect. Eutacta.Conclusions Our results confirm the presence and indicate the survival of Sect. Eutacta in South America during early Antarctic separation. The exceptionally complete fossils significantly predate several molecular age estimates for crown Eutacta. The differentiation of two Araucaria species demonstrates conifer turnover during climate change and initial South American isolation from the early to middle Eocene.