A systematic revision of the Ordovician plectambonitoidean brachiopods Chonetoidea and Sericoidea

The revised Treatise on Invertebrate Paleontology, part H: Brachiopoda regards Chonetoidea Jones and Sericoidea Lindström synonymic, on the basis of characters that were considered common to both genera (e.g. ornament type, number of septules). However, some features (e.g. number of septules) discriminate specimens at species level, rather than at generic level as previously thought. Other morphological features, never taken into account or described before, e.g. the position of the ventral diductor scars or the presence of a pair of septules developed anterolaterally to the socket ridges (named praeculmen septules) in Chonetoidea solely, permit a confident separation of the two genera. The ornament is not useful for diagnosing the genera. A review of all species belonging to each genus is made in light of the emended diagnoses of both Chonetoidea and Sericoidea. Based on the internal morphologies of their lophophoral supporting structures and on sedimentological data, Chonetoidea and Sericoidea are interpreted as living in different bathymetric conditions. Chonetoidea was adapted to a more dynamic environment, with higher nutrient levels. Sericoidea needed a wider area for trapping food, in an environment (open water) with three to six times less nutrients than mid to inner shelf environments. The palaeogeographic and stratigraphic distributions of Chonetoidea and Sericoidea indicate the progressive disappearance of Sericoidea and adaptative radiation of Chonetoidea in a palaeoworld where epicontinental seas were shallowing, prior to the end of Ordovician glaciation events which coincided with the extinction of Chonetoidea

The chalicothere Metaschizotherium bavaricum (Perissodactyla, Chalicotheriidae, Schizotheriinae) from the Miocene (MN5) Lagerstatte of Sandelzhausen (Germany): description, comparison, and paleoecological significance

Within the fossil collection from the Sandelzhausen Lagerstätte in the Upper Freshwater Molasse near Mainburg, Germany, are remains of the schizotheriine chalicothere Metaschizotherium bavaricum, von Koenigswald, 1932. This new material includes elements from a large part of the body, and allows the dentition and postcranial skeleton of Metaschizotherium to be described in detail for the first time. At approximately 16 Ma (MN5), M. bavaricum is now the best-known Early and Middle Miocene European schizotheriine and is important for comparative studies. It differs to some degree from earlier Miocene (MN2–MN4) European material attributed to Moropus sp. or Metaschizotherium wetzleri (Kowalewsky, 1873) and to a larger degree from the Late Miocene species Ancylotherium pentelicum (Gaudry and Lartet, 1856). At Sandelzhausen, M. bavaricum apparently lived in a moist forested environment, where it probably fed on leaves, fruit, and seeds. Members of the Chalicotheriinae, such as Anisodon and Chalicotherium, are not found at Sandelzhausen and may not have been present in Europe at this time. M. bavaricum, like other Schizotheriinae, did not have the bizarre gorilla-like proportions of the Chalicotheriinae. Instead, its general body proportions resemble those of contemporary schizotheriine chalicotheres on other continents, for example, Moropus from North America. M. bavaricum is slightly smaller than the type species of Metaschizotherium, M. fraasi von Koenigswald, 1932 (MN6–MN7) and differs from it in small ways that are still being explored as variation within and differences between these species are clarified. The schizotheriine chalicothere from La Grive St.-Alban (France) referred to M. fraasi by von Koenigswald (Palaeontographica, Beitrage zur Naturgeschichte der Vorzeit 8:1–24, 1932) and Viret (Nouvelles Archives Musée d’Histoire Naturelle de Lyon 6:53–81, 1961) should be restudied and referred to a different taxon.85-12