Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Museo Paleontológico Egidio Feruglio (MEF), Av. Fontana 140, 9100, Trelew, Chubut, Argentina.
L. H. Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, 410 Mann Library Building, Ithaca, NY, 14853, USA.
Am J Bot. 2018 Jun;105(6):1067-1087. doi: 10.1002/ajb2.1113. Epub 2018 Jul 11.
We describe a new araucarian species, Araucaria lefipanensis, from the Late Cretaceous flora of the Lefipán Formation, in Patagonia (Argentina) based on reproductive and vegetative remains, with a combination of characters that suggest mosaic evolution in the Araucaria lineage.
The studied fossils were found at the Cañadón del Loro locality. Specimens were separated into two leaf morphotypes, and their morphological differences were tested with MANOVA.
The new species Araucaria lefipanensis is erected based on the association of dimorphic leaves with cuticle remains and isolated cone scale complexes. The reproductive morphology is characteristic of the extant section Eutacta, whereas the vegetative organs resemble those of the sections Intermedia, Bunya, and Araucaria (the broad-leaved clade).
The leaf dimorphism of A. lefipanensis is similar to that of extant A. bidwillii, where dimorphism is considered to be related to seasonal growth. The leaf dimorphism in A. lefipanensis is consistent with the paleoclimatic and paleoenvironmental reconstructions previously suggested for the Lefipán Formation, which is thought to have been a seasonal subtropical forest. The new species shows evidence of mosaic evolution, with cone scale complexes morphologically similar to section Eutacta and leaves similar to the sections of the broad-leaved clade, constituting a possible transitional form between these two well-defined lineages. More complete plant concepts, especially those including both reproductive and vegetative remains are necessary to understand the evolution of ancient plant lineages. This work contributes to this aim by documenting a new species that may add to the understanding of the early evolution of the sections of Araucaria.
本研究基于生殖和营养器官，描述了来自巴塔哥尼亚（阿根廷）晚白垩世 Lefipán 组的新南洋杉物种—— Lefipánensis。该物种的特征组合表明在南洋杉谱系中存在镶嵌进化。
研究化石发现于 Cañadón del Loro 地区。将标本分为两种叶形态型，并使用 MANOVA 检验它们的形态差异。
新物种 Araucaria lefipanensis 是根据具有表皮残余物的二形叶和孤立的球果鳞片组合而建立的。生殖形态特征与现生的 Eutacta 组相似，而营养器官则与 Intermedia、Bunya 和 Araucaria（宽叶分支）组相似。
Lefipánensis 的叶片二形性与现生的 A. bidwillii 相似，而二形性被认为与季节性生长有关。Lefipánensis 的叶片二形性与先前对 Lefipán 组提出的古气候和古环境重建一致，认为该组为季节性亚热带森林。新物种表现出镶嵌进化的证据，其球果鳞片形态上与 Eutacta 组相似，叶片与宽叶分支的组相似，构成了这两个明确谱系之间的可能过渡形式。为了更好地理解古植物谱系的进化，需要更完整的植物概念，特别是包括生殖和营养器官的概念。本研究通过记录一个可能有助于理解 Araucaria 各节早期进化的新物种，为此做出了贡献。
