Pipimorpha and its crown-group Pipidae possess one of the most extensive fossil records among anurans, which extends into the Early Cretaceous in both Laurasia and Gondwana. This is probably linked to the highly aquatic lifestyle of pipids, which is probably also characteristic of early pipimorphs. In South America, pipids are currently represented only by Pipa, but the fossil record documents an evolutionary radiation of Shelaniinae (a taxon endemic to South America) in the Cretaceous; shelaniines seem to have become extinct in the Eocene. Fewer pipimorph fossils are known from Africa. Our recent redescription of the mid-Late Cretaceous (Coniacian–Santonian) taxon Pachycentrata taqueti from In Becetèn (Niger) partly fills this gap. Our new phylogenetic analysis of Cretaceous and Paleogene pipimorphs shows that this taxon diversified in a West Gondwanan block until about the mid-Cretaceous, but after that, pipimorphs show two distinct evolutionary radiations, one in South America (Pipinae), and the other (Xenopodinae) in Africa. This pattern appears to reflect the breakup of West Gondwana simultaneously with the opening of the South Atlantic during the Cretaceous. This probable vicariant pattern yields slightly different ages for the South Atlantic opening depending on the accepted topology. The tree constrained to reflect the topology of extant taxa supported by molecular data shows a last dispersal between both continents before the Cenomanian (more than 100 Ma), whereas the unconstrained topology that reflects only morphological data is compatible with a more recent last faunal dispersal among pipids. Under this unconstrained topology, the fossil record is too poor to give a reliable minimal age for this last dispersal, but molecular dating analyses suggest that this event harks back to the Mesozoic.
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RBINS Staff Publications 2024 OA
The Senne River has shaped the landscape and development of Brussels for centuries. However, its course and environmental conditions have been continuously altered by human interventions. This study compares freshwater mollusc and caddisfly (Trichoptera) remains from two archaeological sites, one Gallo-Roman (1st-3rd century AD) and one medieval (10th-16th century AD), to reconstruct changes in river flow, sedimentation, and water quality over time. At the Gallo-Roman site, a previously unknown river meander of the Senne river was uncovered, initially characterized by fast-flowing water, as indicated by coarse sand and gravel deposits. Over time, sedimentation patterns show a shift to finer materials, such as silt and organic muds, suggesting a transition to slower-moving or stagnant water before the meander was ultimately cut off. The site is located within a rural environment. In contrast, the medieval site, located within the historic centre of Brussels, represents a heavily modified urban river environment. Mollusc remains indicate predominantly slow-moving water, with occasional stagnant conditions. The discovery of caddisfly larvae cases, including the confirmed presence of Brachycentrus subnubilus, suggests that despite extensive waste dumping, parts of the medieval Senne still maintained sufficient water quality for oxygen-dependent species. By combining data from these two sites, this study attempts to document the Senne’s hydrology, sedimentation, and aquatic ecosystems in a rural and urban environment. The findings describe the river’s natural environment alongside increasing human impact, from early riverbank modifications in Gallo-Roman times to the canalization and pollution of the medieval period.
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RBINS Staff Publications 2025
