Sciency Thoughts: Tuebingosaurus maierfritzorum: A new species of Massopodan Sauropodomorph Dinosaur from the Palaeontological Collection of the University of Tübingen.

Monday, 31 October 2022

Tuebingosaurus maierfritzorum: A new species of Massopodan Sauropodomorph Dinosaur from the Palaeontological Collection of the University of Tübingen.

The Palaeontological Collection of the University of Tübingen contains one of the largest assemblages of Sauropodomorph Dinosaurs in Europe, but also one of the least studied. Much of this material was collected from sites around Tübingen, Aixheim and Löwenstein in the nineteenth and early twentieth centuries and classified under the genus Plateosaurus.

The genus Plateosaurus was once used to classify almost all non-Sauropod Sauropodomorph Dinosaurs, and by the mid twentieth century contained over 20 species, of which only four are considered valid today. Unfortunately, while it is now recognised that the non-Sauropod Sauropodomorph Dinosaurs are a more diverse group than once understood, and that understanding this diversity is the key to understanding the emergence of the true Sauropods, one of the most remarkable groups of organisms ever to appear on Earth, several rival schemes for the classification of this group have appeared, hampering this understanding.

In a paper published in the journal Vertebrate Zoology on 8 September 2022, Omar Rafael Regalado Fernández of the Fachbereich Geowissenschaften an der Universität Tübingen, and Ingmar Werneburg, also of the Fachbereich Geowissenschaften an der Universität Tübingen, and of the Senckenberg Centre for Human Evolution and Palaeoenvironment an der Universität Tübingen, describe a new species of Sauropodomorph Dinosaur from the Palaeontological Collection of the University of Tübingen, based upon a specimen, GPIT-PV-30787, collected from Lower Dinosaur Bed at Obere Mühle in 1932.

The complex nature of Sauropodomorph Dinosaur taxonomy meant that Regalado Fernández and Werneburg were obliged to carry out multiple phylogenetic analyses in order to try to accommodate specimen GPIT-PV-30787 into the competing phylogenies for the group. Fortunately, these produced reasonably consistent results, with the specimen being found to be closely related to Schleitheimia schutzi, making it a Massopodan Sauropodomorph, close to the origin of the true Sauropods.

Based upon this information, Regalado Fernández and Werneburg describe specimen GPIT-PV-30787 as the holotype of a new species, giving it the name Tuebingosaurus maierfritzorum, where 'Tuebingosaurus' refers to Tübingen and 'maierfritzorum' honours Wolfgang Maier, professor of evolutionary zoology in Tübingen from 1987 to 2007, and Uwe Fritz, former editor-in-chief of the journal Vertebrate Zoology.

Specimen GPIT-PV-30787 comprises a complete pelvis (three sacral vertebrae, two ilia, two pubes, two ischia), five anterior caudal vertebrae, four chevrons, left femur, left tibia, left and right fibulae, left astragalus, left calcaneum, metatarsal I, and pedal fingers 3 and 4.

Reconstruction of Tuebingosaurus maierfritzorum, as a quadruped Dinosaur, using the outline of Riojasaurus as a base, next to the silhouette of Friedrich von Huene. The drawing of the bones is based on and modified from the original illustrations of specimen 'GPIT IV' (the name originally ascribed to GPIT-PV-30787) by von Huene. The right fibula is marked in grey as it was found nearby with similar measurements to the left fibula and has been assumed to be part of the same individual. Regalado Fernández & Werneburg (2022).

Regalado Fernández and Werneburg's phylogeny suggests that Tuebingosaurus maierfritzorum is a Massopodan, making it the earliest member of the group known from the Upper Triassic Trossingen Beds. Despite this taxonomic placement, Tuebingosaurus maierfritzorum still shares a number of features more generally associated with Plateosaurian Sauropodomorphs, most notably a heel-like projection in the posterior part of the ischiadic peduncle of the ilium and a straight lateral margin in metatarsal II, features which led to the assumption that this was a specimen of Plateosaurus.

This presence of Plateosaurian-like features in early Massopodan Dinosaurs is unlikely to be unique to Tuebingosaurus maierfritzorum, and re-examination of other historic specimens at Tübingen and other palaeontological collections may provide more examples, helping to unravel the origins of the Sauropods.

Reconstruction of the last moments in the life of Tuebingosaurus maierfritzorum (collection number of the painting: GPIT-PV-41827). The cortical bone on the left side of the fossil is fractured into flakes, which can be explained if the carcass was exposed over a long time on the mud, two to four years, before being buried – in the reconstruction, the Animal will fall to its right body side. The reconstruction shows the animal sinking in a mud trap, attacked by a Rauisuchian, Teratosaurus, which has also been found in the Trossingen Formation in Baden-Württemberg. In the background, a herd of Plateosaurus trossingensis runs away from the scene. The flora in the swamp is reconstructed based on fossils from the Germanic basin, with shoots of Horsetails and Ferns covering the swamp and a forest comprising Cycads (Taeniopteris), Lycophytes (Lepacyclotes) and Coniferous Plants (Brachyphyllum). Regalado Fernández & Werneburg (2022).