除了世界著名的化石地点梅塞尔和布克斯维莱之外,莱茵河上游地堑(德国西南部)裂谷前阶段的始新世生物群鲜为人知。虽然在这些地点仅发现了陆地和淡水化石,但在这里我们展示了来自莱茵河上游地堑中部的花卉和动物组合,这些组合清楚地表明暂时的咸水环境,并由多样化的孢粉群、钙质超小型浮游生物、有孔虫、介形类和一些鱼类组成和爬行动物遗骸。根据Trochastrites hohnensis 的出现情况,推测卢特阶时代。有有机壁的甲藻包囊,特别是Phthanoperidinium comatum、Phthanoperidinium echinatum、Apetodiniumhomomorphum和Apetodinium quinquelatum,表明年龄为伊普雷世晚期到卢特阶期。花粉和孢子组合包括典型的始新世中期物种,例如Tegumentisporis villosoides、Tricolporopollenites crassostriatus和 Bombacaceae 的代表,但不能排除伊普雷世晚期到普里亚波尼世的年龄。有孔虫和介形类没有进一步完善生物地层分配。因此,最有可能是卢特阶时代。Neocyprideis 、各种有孔虫类群和多样性极低的有机壁甲藻包囊组合的大量出现表明存在微咸水环境。脱节的脊椎动物遗骸包括鳞鱼科的鱼牙、龟板以及双齿龙和哈西亚科鳄的鳄鱼牙齿。目前的古地理情景并未考虑始新世中期从莱茵河上游地堑与北海盆地、高山海/副特提斯海或巴黎盆地的连接。假设莱茵河上游地堑中部是内陆,并且在这段时间内绝对不会受到海洋入侵,我们初步认为微咸水类群可能是通过风(风)、雨、高度流动的昆虫或脊椎动物,如鱼类、鸟类和哺乳动物(内动物/外动物)。新近描述了可能是淡水钙质超小型浮游生物种Nannoserratolithus minutus Martini。
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Eocene sediments and a fresh to brackish water biota from the early rifting stage of the Upper Rhine Graben (west of oil field Landau, southwest Germany): implications for biostratigraphy, palaeoecology and source rock potential
The Eocene biota from the pre-rifting stage of the Upper Rhine Graben (southwest Germany) is, with exception of the world-famous fossil sites Messel and Bouxwiller, poorly known. While from these localities exclusively terrestrial and freshwater fossils were recovered, here we present floral and faunal assemblages from the middle Upper Rhine Graben which clearly indicate a temporarily brackish water environment and consist of a diverse palynomorph association, calcareous nannoplankton, foraminifers, ostracods and some fish and reptile remains. Based on the occurrence of Trochastrites hohnensis, a Lutetian age is assumed. Organic-walled dinoflagellate cysts, in particular Phthanoperidinium comatum, Phthanoperidinium echinatum, Apectodinium homomorphum and Apectodinium quinquelatum, suggest a late Ypresian to Lutetian age. The pollen and spores assemblage includes typical mid Eocene species, such as Tegumentisporis villosoides, Tricolporopollenites crassostriatus and representatives of Bombacaceae, but a late Ypresian to Priabonian age cannot be excluded. Foraminifers and ostracods do not further refine the biostratigraphical assignment. Hence, a Lutetian age is most probable. The mass occurrence of Neocyprideis, various foraminifer taxa and an organic-walled dinoflagellate cyst assemblage of very low diversity are indicative of a brackish water environment. Disarticulated vertebrate remains include fish teeth of Lepisosteidae, turtle plates and alligatoroid teeth of Diplocynodon and Hassiacosuchus. The present palaeogeographical scenarios do not consider a connection from the Upper Rhine Graben to the North Sea Basin, Alpine Sea/Paratethys or Paris Basin during the mid Eocene. Provided that the middle Upper Rhine Graben was land-locked and definitely not reached by a marine ingression during this time interval, we tentatively suggest that the brackish water taxa may have been accidentally introduced into a brackish inland sea by wind (anemochory), rain, highly mobile insects or vertebrates such as fish, birds and mammals (endozoochory/ectozoochory). The presumably freshwater calcareous nannoplankton species Nannoserratolithus minutus Martini is newly described.