Neogene flora and vegetation development in the Pannonian domain in relation to palaeoclimate and palaeogeography

A survey of the Neogene flora and vegetation pattern of the Pannonian domain based on selected fossil plant assemblages is given. The paper aims to reveal the complex interrelation of tectonic-palaeogeographic evolution, climate, flora and vegetation development through the Neogene of the Pannonian domain. Flora and vegetation patterns are based on well-documented and studied fossil plant assemblages (macrofloras, primarily leaves). There are time intervals well-represented in the fossil record, e.g. the Pannonian or the Sarmatian and others with relatively few localities, e.g. the Badenian. A general but slow cooling trend is definitely observable after the Early Miocene as reflected by both quantitative climate reconstructions and floristic change, i.e. decrease of diversity, slow disappearance of thermophilous and exotic elements, as well as decrease in the variety of vegetation types. A significant decline of coldest month temperatures (as compared to warmest month temperatures) must have played a defining role in forming flora and vegetation through the Neogene. As compared to climate estimates for the Middle/Late Miocene fossil floras, warmer climate conditions are indicated by the Ipolytarnóc flora and vegetation comprising an extremely high number of thermophilous taxa as well as complex vegetation structure. The Early and Middle Miocene fossil assemblages bear a significant relevance to the tectonic pattern of the Pannonian domain. A transitional character in both flora and vegetation is indicated by the Karpatian Magyaregregy locality.Knowledge of the Badenian flora and vegetation is limited to the Middle Badenian Nógrádszakál assemblage indicating cooler climate conditions which contrasts with global climate change. In contrast to the relatively poor azonal vegetation of Nógrádszakáland most Pannonian localities, the more diverse Sarmatian and Pliocene floras display a strong relation to each other—attributable to palaeogeographic constraints

<i>Asclepiadospermum</i> gen. nov., the earliest fossil record of Asclepiadoideae (Apocynaceae) from the early Eocene of central Qinghai-Tibetan Plateau, and its biogeographic implications

Premise: Apocynaceae is common in the fossil record, especially as seed remains from the Neogene of Europe and North America, but rare in Asia. Intrafamilial assignment is difficult due to the lack of diagnostic characters, and new fossil and modern data are needed to understand the paleobiogeography of this group. Methods: We studied three Apocynaceae seed impressions from the Lower Eocene Niubao Formation, Jianglang village, Bangor County, central Qinghai-Tibetan Plateau. Morphological data from living and fossil species were phylogenetically mapped to enable systematic assignment. Results: We describe a new genus, Asclepiadospermum gen. nov., and two new species, A. marginatum sp. nov. and A. ellipticum sp. nov. These species are characterized by an elliptical seed, a margin surrounding the central part of the seed, and polygonal, irregular, and small epidermal cells, and differ mainly in terms of the size of the margin and the shape of the apex. All these characters indicate that this new genus belongs to the subfamily Asclepiadoideae (Apocynaceae). Conclusions: These fossils represent the earliest fossil seed records of Asclepiadoideae. Asclepiadospermum indicates a humid tropical to subtropical flora during the early Eocene in central Tibet. Moreover, our discoveries indicate a close floristic connection between Eurasia and Africa during the early Eocene, which expands our knowledge of the floristic linkage between Tibet and other regions at that time

No post-Cretaceous ecosystem depression in European forests? Rich insect-feeding damage on diverse middle Palaeocene plants, Menat, France

Insect herbivores are considered vulnerable to extinctions of their plant hosts. Previous studies of insect-damaged fossil leaves in the US Western Interior showed major plant and insect herbivore extinction at the Cretaceous–Palaeogene (K–T) boundary. Further, the regional plant–insect system remained depressed or ecologically unbalanced throughout the Palaeocene. Whereas Cretaceous floras had high plant and insect-feeding diversity, all Palaeocene assemblages to date had low richness of plants, insect feeding or both. Here, we use leaf fossils from the middle Palaeocene Menat site, France, which has the oldest well-preserved leaf assemblage from the Palaeocene of Europe, to test the generality of the observed Palaeocene US pattern. Surprisingly, Menat combines high floral diversity with high insect activity, making it the first observation of a ‘healthy’ Palaeocene plant–insect system. Furthermore, rich and abundant leaf mines across plant species indicate well-developed host specialization. The diversity and complexity of plant–insect interactions at Menat suggest that the net effects of the K–T extinction were less at this greater distance from the Chicxulub, Mexico, impact site. Along with the available data from other regions, our results show that the end-Cretaceous event did not cause a uniform, long-lasting depression of global terrestrial ecosystems. Rather, it gave rise to varying regional patterns of ecological collapse and recovery that appear to have been strongly influenced by distance from the Chicxulub structure