New marsileaceous fossils from the Late Cretaceous of South America and a reevaluation of Marsileaceaephyllum
New marsileaceous fossils from the Late Cretaceous of South America and a reevaluation of Marsileaceaephyllum
复制标题
南美洲晚白垩世新的马西古化石和马西科植物的重新评估
DOI：
--
复制
发表时间：
2014
影响因子：
1.9
通讯作者：
N. Cúneo
中科院分区：
文献类型：
--
作者：
E. Hermsen;M. Gandolfo;N. Cúneo
本文报道了阿根廷丘布特省La科洛尼亚组Campanian至Maastrichtian Cañadón del Irupé地区水生蕨类植物Marsileaceae的新的大型化石和相关的微体化石。大型化石包括复叶、离生小叶和孢子果。小叶的脉络与Marsileaceaephyllum的诊断一致，我们认为这是不明确的。因此，修订了Marsileaceaephyllum的界限和诊断，以限制该分类单元仅包括叶或根茎，其叶具有四个小叶，最像Marsileaceae现存属中的Marsilea。Cañadón del Irupé的叶和小叶被分配到新属Mirasolita，直立以包括具有两个小叶柄小叶的复叶，每个小叶具有肾形叶片和网状脉序。Mirasolita叶和小叶的结构不同于任何活的marsilaceae属的叶。有柄子实体被指定为新属Lugiomarsiglia。它们被认为是Marsileaceae，因为每一个都有一个厚壁细胞壁包围着圆形的身体，解释为孢子囊。相关的大孢子被分配给Molaspora lobata，这是一种地理上广泛分布的、主要是晚白垩世分散孢子分类群。Molaspora lobata与灭绝的marsileaceous叶子形式的共存符合一种模式，其中白垩纪Regnellidium样大孢子与显示多种形态的marsileaceous宏化石相关或原位发现。
Herein we report new macrofossils and associated microfossils representing the aquatic fern family Marsileaceae from the Campanian to Maastrichtian Cañadón del Irupé locality, La Colonia Formation, Chubut Province, Argentina. The macrofossils include compound leaves, detached leaflets, and sporocarps. The venation of the leaflets is consistent with the diagnosis of Marsileaceaephyllum, which we argue is poorly defined. Consequently, the circumscription and diagnosis of Marsileaceaephyllum are emended in order to limit the taxon to include only leaves or rhizomes bearing leaves with four leaflets that most resemble those of Marsilea among extant genera of Marsileaceae. The Cañadón del Irupé leaves and leaflets are assigned to the new genus Mirasolita, erected to encompass compound leaves bearing two petiolulate leaflets, each leaflet having a reniform lamina and reticulate venation. The architecture of Mirasolita leaves and leaflets is distinct from that of leaves of any of the living marsileaceous genera. The stalked sporocarps are assigned to the new genus Lugiomarsiglia. They are attributed to Marsileaceae because each has a sclerenchymatous wall surrounding circular bodies interpreted as sporangia. Associated megaspores are assigned to Molaspora lobata, a geographically widespread, primarily Late Cretaceous dispersed spore taxon. The co-occurrence of Molaspora lobata with an extinct marsileaceous leaf form fits a pattern wherein Cretaceous Regnellidium-like megaspores are associated with or found in situ within marsileaceous macrofossils that display a variety of morphologies.