The Wasatchian Wa-0 mammalian fauna from the Paleocene-Eocene Thermal Maximum (earliest Eocene) is reasonably well sampled in North America, but mammals of small body size are still poorly known. Here we describe a new species of the insectivore Didelphodus based on a cranial rostrum, both dentaries, and a nearly complete upper and lower dentition, all found by screen-washing. The new species, D. caloris, is the oldest species of the genus known in North America. It differs from later early Eocene Didelphodus in being substantially smaller, in having relatively simple premolars, and in having a more reduced M3 relative to preceding molars. Precursors of Didelphodus are not known with certainty, and the species D. caloris may be an immigrant to mid-continent North America. D. caloris is tentatively interpreted as a dwarfed form like other Wa-0 mammals because of its small size relative to the better-known successor species D. absarokae.
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RBINS Staff Publications 2023
A detailed structural mapping and geometrical analysis of distinct bedding-(sub)perpendicular and bedding-parallel quartz veins has been performed in the northeastern part of the High-Ardenne slate belt (Rursee, North Eifel, Germany), with the aim to reconstruct the local fracturing/veining history. The structural relationship of these two types of veins as well as their relationship with cleavage, folds and faults allows attributing a pre- to early-Variscan age to these veins. The first type of veins is oriented (sub)perpendicular to bedding and consists of several, mutual cross-cutting generations, which clearly predate Variscan deformation. The second type of veins, bedding-parallel veins, post-dates the bedding-(sub)perpendicular veins and reflects bedding-parallel thrusting at the onset of Variscan deformation, predating folding. Subsequently, during progressive Variscan compression both types of veins were passively folded within characteristic, NW-vergent, overturned folds. Locally, due to flexural slip folding, reactivation along the bedding-parallel veins may have taken place.
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A chitinozoan biozonation is established for the Upper Ordovician rocks of the Sennette valley in the Fauquez area and the Asquempont area, revising the existing chitinozoan biozonation of the Brabant Massif. The chitinozoans of fi ve formations (the Ittre, Bornival, Huet, Fauquez and Madot formations) are studied from 70 samples. The chitinozoan biozonation is correlated with Baltoscandia and the Avalonian Upper Ordovician type sections in the U.K. This correlation provides an accurate dating of the studied formations. A megaslumping event, affecting a part of the Ittre and Bornival Formation and causing the overturning of a pile of sediments estimated at minimum 200 m thick, may be placed in the mid Oandu (Cheneyan, middle Caradoc, early “Stage 6”). The volcanic rocks in the Fauquez area, formally thought to be restricted to the Ashgill, are confi ned to the late Caradoc - early Ashgill timespan. In addition to this, this paper presents new lithostratigraphical data on the Ittre Formation and the lower member of the Bornival Formation.
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