Hard work breaks no bones: A bone from the Wealden facies gets revealed

Jens Lehmann (Germany) The recent find of a big slab of Early Cretaceous lumachelle limestone of the Wealden facies containing a bone (Figs. 1 and 2) made for a time-consuming and technically ambitious preparation process. (Lumachelle limestone is a compact limestone or marble containing fragments of shells, encrinites and other fossils, which are sometimes iridescent, and display a variety of brilliant colours.) The specimen looked disappointing at first sight, but the end result made the hard work worthwhile, as I discuss below. Indeed, the following is intended as an example of the technical aspects of palaeontology, which are too often forgotten or ignored. The specimen was discovered in a loose, but very heavy slab on the beach. Therefore, efforts were made to reduce the size of the rock in the field to make it easier to carry, but, unfortunately, it broke into two pieces (Figs. 1 and 2). Fig. 1. A bone in a limestone from the Early Cretaceous (Barremian, Wealden facies), broken while preparing the slab in the field. Fig. 2. Reverse side of the limestone slab, with masses of freshwater bivalves making up most of the boulder. The original surface of the bone was completely worn – with no details preserved (Fig. 3A) and therefore a transfer preparation had to be planned. On the other side, the cross section (Fig. 3B) gave me a pretty good idea of the shape of the bone before preparation and the exact thickness of the rock that would have to be removed … Read More

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