Two-pronged kill mechanism at the end-Triassic mass extinction

High-resolution biomarker and compound-specific isotope distributions coupled with the degradation of calcareous fossil remnants reveal that intensive euxinia and decalcification (acidification) driven by Central Atlantic magmatic province (CAMP) activity formed a two-pronged kill mechanism at the end-Triassic mass extinction. In a newly proposed extinction interval for the basal Blue Lias Formation (Bristol Channel Basin, UK), biomarker distributions reveal an episode of persistent photic zone euxinia (PZE) that extended further upward into the surface waters. In the same interval, shelly taxa almost completely disappear. Beginning in the basal paper shales of the Blue Lias Formation, a Lilliput assemblage is preserved consisting of only rare calcitic oysters (Liostrea) and ghost fossils of decalcified aragonitic bivalves. The stressors of PZE and decalcification parsimoniously explain the extinction event and inform possible combined causes of other biotic crises linked to emplacement of large igneous provinces, notably the end-Permian mass extinction, when PZE occurred on a broad and perhaps global scale.

Global ecomorphological restructuring of dominant marine reptiles prior to the K/Pg mass extinction

Mosasaurid squamates were the dominant amniote predators in marine ecosystems during most of the Late Cretaceous. Evidence from multiple sites worldwide of a global mosasaurid community restructuring across the Campanian-Maastrichtian transition may have wide-ranging implications for the evolution of diversity of these top oceanic predators. In this study, we use a suite of biomechanical traits and functionally descriptive ratios to investigate how the morphofunctional disparity of mosasaurids evolved through time and space prior to the Cretaceous-Palaeogene (K/Pg) mass extinction. Our results suggest that the worldwide taxonomic turnover in mosasaurid community composition from Campanian to Maastrichtian is reflected by a notable increase in morphofunctional disparity on a global scale, but especially driven the North American record. Ecomorphospace occupation becomes more polarised during the late Maastrichtian, as the morphofunctional disparity of mosasaurids plateaus in the Southern Hemisphere and decreases in the Northern Hemisphere. We show that these changes are not associated with strong modifications in mosasaurid size, but rather with the functional capacities of their skulls, and that mosasaurid morphofunctional disparity was in decline in several provincial communities before the K/Pg mass extinction. Our study highlights region-specific patterns of disparity evolution, and the importance of assessing vertebrate extinctions both globally and regionally. Ecomorphological differentiation in mosasaurid communities, coupled with declines in other formerly abundant marine reptile groups, indicates widespread restructuring of higher trophic levels in marine food webs was well underway when the K-Pg mass extinction took place.

Means and Meanings of Research Collaboration in the Face of a Suffering Earth: A Landscape of Questions

The Earth is speaking to us in its own language of suffering—rising average temperatures, increasingly extreme weather conditions, mass extinction of species and so on. Academic habits of travelling long distances and/or frequently, as many of us have, affect the Earth and its inhabitants. This chapter argues the need for changing habits not just by developing technical infrastructure but through developing awareness among academics of the issues involved including the dynamics that may be slowing down change. The chapter contributes by discussing the means and meanings of research collaboration in this context. We explore the role of collaboration across distance in scholarship (Erkenntnis), various ways (technical and otherwise) that materialities can affect remote collaboration and reflect on the ethics of commitments intrinsic to academic work. The challenge facing academics is to integrate these three aspects—sharing, the material/technical and the ethical—in developing ways of working which are responsive to the Earth crises. To support this, we indicate a set of questions which can be helpful to consider when, as scholars, we make decisions about why and how to collaborate.

Supplemental Material: Mass extinction or extirpation: Permian biotic turnovers in the northwestern margin of Pangea

Illustrations of Permian brachiopod species from the Kapp Statostin Formation in Spitsbergen and their detailed stratigraphic ranges.

Supplemental Material: Mass extinction or extirpation: Permian biotic turnovers in the northwestern margin of Pangea

Illustrations of Permian brachiopod species from the Kapp Statostin Formation in Spitsbergen and their detailed stratigraphic ranges.