Review of the non-tritylodontid synapsids from bone beds in the Rhaetic Sandstone, southern Germany

Abstract

Since the nineteenth century, bone beds in the Rhaetic Sandstone (Rhatsandstein) exposed around Bebenhausen near Tubingen, Baden-Wurttemberg, have been a source of small vertebrate fossils. These bone beds were part of deltas formed during a stillstand in a marine transgression from the western and northern parts of the Germanic Basin. The fossils in these bone beds appear to be time-averaged assemblages of Rhaeto-Liassic or older age. A collection of fossils from excavations at Olgahain made in 1948 augmented those reported by E. von Huene (Jahreshefte des Vereins vaterlandische Naturkunde in Wurttemberg 84:65–128, 1933). The synapsids, other than tritylodonts, represented by fossils from the Olgahain locality include Tricuspes, a non-mammaliaform eucynodont; the haramiyid Thomasia antiqua is the most abundantly represented mammaliaform, and a morganucodontid. Tricuspes tuebingensis was based on a tooth found at the nearby Gaisbrunnen locality. Tricuspes tuebingensis, Thomasia antiqua, and a probably different morganucodontid are known from the Hallau bone bed (Switzerland), which apparently is older than the Olgahain bone bed in Baden-Wurttemberg.