Sakmarian Permian Chemnitz Petrified Forest was a wet Oasis in a Variable Semi Arid/Semi Humid Climate

Palaeoclimatic and site-specific conditions in the early Permian fossil forest of Chemnitz—Sedimentological, geochemical and palaeobotanical evidence

Authors:

Luthardt et al

Abstract:

As significant indicators of deep-time palaeoclimate, a number of new palaeontological, pedological and geochemical characteristics are provided for the Chemnitz Fossil Lagerstätte to depict more precisely its environmental conditions. For the first time, several lines of evidence indicate that this fossil forest, instantaneously preserved by volcanic deposits, once received an annual precipitation of around 800–1100 mm, but grew on a nearly unweathered palaeosol. Although the composition of this rich and diverse T0 assemblage suggests a hygrophilous, dense and multi-aged vegetation dominated by conservative lineages, the habitat was affected by environmental disturbances and pronounced seasonality. Repeated changes in local moisture availability are suggested by geochemical proxies, the co-occurrence to intergrowth of calcic and ferric glaebules in the palaeosol and developmental traits of perennial vegetational elements. Specific substrate adaptation is reflected by different root systems and cyclic growth interruptions recorded in the stems, branches and roots of long-lived woody plants. Many differentially adapted terrestrial animals complete the more comprehensive reconstruction of a late Sakmarian ecosystem and its climatic and preservational controls. Albeit spatially confined, this diverse in-situ record may contribute to understand wetland–dryland dynamics of sub-tropical Northern Hemisphere Pangaea.

Week of Vintana: Sudamericid Gondwanatherian Mammal Vtiana Lived in Seasonal, Semiarid Coastal Floodplain of Maastrichtian Cretaceous Madagascar

Introduction, Systematic Paleontology, and Geological Context of Vintana Sertichi (Mammalia, Gondwanatheria) from the Late Cretaceous of Madagascar

Authors:

Krause et al

Abstract:

Vintana sertichi is a sudamericid gondwanatherian mammal known only from the Upper Cretaceous (Maastrichtian) Maevarano Formation in the Mahajanga Basin of northwestern Madagascar. It is based on a single specimen, a well-preserved and virtually complete cranium discovered in 2010 near Lac Kinkony. The cranium is superficially bizarre and constitutes the only cranial remains of the poorly known, phylogenetically enigmatic Gondwanatheria, which are otherwise known only from isolated teeth and fragmentary dentaries. Gondwanatheria are represented by seven other monotypic genera assigned to two families (Ferugliotheriidae and Sudamericidae). Historically, this clade was assigned to Xenarthra, Paratheria (as a sister group to Xenarthra), Multituberculata, Allotheria (as a sister group to Multituberculata), Mammalia incertae sedis, and, most recently, back to Multituberculata or a close relative of Multituberculata. The craniodental evidence provided by Vintana supports inclusion in Sudamericidae, the monophyly of Gondwanatheria, and the position of Gondwanatheria as nested within or sister to Multituberculata. In addition to briefly reviewing the taxonomic composition and phylogenetic history of Gondwanatheria, this introductory chapter sets the stage for the other chapters in the volume by (1) briefly summarizing the inferred life habits of gondwanatherians; (2) reviewing the systematic paleontology of V. sertichi; and (3) providing overviews of the discovery of the holotypic specimen, its preservation, its preparation, and the imaging and measurement techniques used to study it. The chapter closes with an overview of the geological context of V. sertichi, which indicates that the species lived in a coastal floodplain environment and in a highly seasonal, semiarid climate.

Semi Arid Climates may be Resistant to Climate Change

Climate change predictions for the Middle East, like other arid regions of the world, are alarming. In an area known for its water scarcity, rainfall is expected to decrease even further in the near future, spelling disaster for the functioning of unique ecosystems — hotspots of biodiversity and rich genetic fodder for essential crops.

To test these dire predictions, Prof. Marcelo Sternberg of the Department of Molecular Biology and Ecology of Plants at Tel Aviv University's Faculty of Life Sciences, together with ecologists from the University of Tübingen in Germany, subjected natural ecosystems to an experimental drought over the course of nine years, simulating predicted future climate scenarios.

In the course of their experiment, conducted in four different ecosystems ranging from desert (3.5 inches of annual rainfall) to moist Mediterranean woodland (30.7 inches of annual rainfall), the researchers found that, contrary to predictions, no measurable changes in annual vegetation could be seen. None of the crucial vegetation characteristics — neither species richness and composition, nor density and biomass (particularly important for ecosystems traditionally used as rangelands) — had changed appreciably in the course of the rainfall manipulations.

"Based on our study, the going hypothesis that all semiarid regions will react strongly to climate change needs to be revised," states Prof. Sternberg. The surprising results of the study were recently published in Nature Communications.

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