A new species of Macrocnemus from the Middle Triassic of the eastern Swiss Alps
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A new species of Macrocnemus from the Middle Triassic of the eastern Swiss Alps Nicholas Fraser • Heinz Furrer
Received: 12 February 2013 / Accepted: 3 July 2013 / Published online: 16 November 2013 Ó Swiss Geological Society 2013
Abstract A new species of Macrocnemus is described on the basis of two incomplete specimens from the Lower Ladinian Prosanto Formation of southeastern Switzerland. The new form can be distinguished by its gracile limb elements and having a noticeably longer tibia than either Macrocnemus bassanii or Macrocnemus fuyuanensis. One of the new specimens exhibits soft part preservation in the region of the pelvic girdle. The hind part of this individual is preserved fully articulated and allows a complete count of the caudal vertebrae to be made for the first time with 52 caudals. It is postulated that this specimen was predated upon and that the anterior part of the animal was consumed by a large predator such as a nothosaurid reptile or the actinopterygian fish Saurichthys. Keywords
Protorosaur Europe Triassic Tethys
Institutional abbreviations PIMUZ Pala¨ontologisches Institut und Museum, University of Zu¨rich, Zu¨rich, Switzerland IVPP Institute of Vertebrate Palaeontology and Palaeoanthropology, Beijing, China GMPKU Geological Museum, Peking University, Beijing, China
Editorial handling: L. Cavin & D. Marty. N. Fraser (&) National Museums Scotland, Chambers Street, Edinburgh EH4 2BA, UK e-mail: [email protected] H. Furrer Pala¨ontologisches Institut und Museum der Universita¨t Zu¨rich, Karl Schmid-Strasse 4, 8006 Zu¨rich, Switzerland
1 Introduction The protorosaur Macrocnemus is well known from the Besano Formation (Grenzbitumenzone) of the southern Alps (Monte San Giorgio area in southern Switzerland and northern Italy). It was first described by Nopcsa (1930) as Macrochemus on the basis of a rather poorly preserved specimen then held in the Museo Civico di Storia Naturale in Milano. Unfortunately, this specimen was destroyed during World War II. The name Macrocnemus was first used by F. Bassani on the original specimen label (Peyer 1937; Nopcsa 1930). Peyer’s subsequent excavations in the Besano Formation of Monte San Giorgio resulted in the recovery of much more material and provided the basis of a monographic study of a single species, Macrocnemus bassanii (Peyer 1937). The description relied heavily on one particular specimen, PIMUZ T 4822, which was actually recovered from the somewhat younger Cassina beds of the Meride Formation. Shortly after publication of the monograph another beautifully preserved specimen was excavated. This specimen, PIMUZ T 2472, was described by Kuhn-Schnyder (1962), although his description centred only on the skull, which is surprising given the state of completeness of the specimen. Rieppel and Gronowski (1981), Rieppel (1989), and Renesto and Avanzini (2002) added further detail to the original descriptions. Recently, a second species was described from the Middle Triassic of southern China (Li et al. 2007; Jiang et al. 2011). Despite the gr
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