Oliver Wings

Biology of the sauropod dinosaurs: the evolution of gigantism

The herbivorous sauropod dinosaurs of the Jurassic and Cretaceous periods were the largest terrestrial animals ever, surpassing the largest herbivorous mammals by an order of magnitude in body mass. Several evolutionary lineages among Sauropoda produced giants with body masses in excess of 50 metric tonnes by conservative estimates. With body mass increase driven by the selective advantages of large body size, animal lineages will increase in body size until they reach the limit determined by the interplay of bauplan, biology, and resource availability. There is no evidence, however, that resource availability and global physicochemical parameters were different enough in the Mesozoic to have led to sauropod gigantism.

No gastric mill in sauropod dinosaurs: new evidence from analysis of gastrolith mass and function in ostriches

Polished pebbles occasionally found within skeletons of giant herbivorous sauropod dinosaurs are very likely to be gastroliths (stomach stones). Here, we show that based on feeding experiments with ostriches and comparative data for relative gastrolith mass in birds, sauropod gastroliths do not represent the remains of an avian-style gastric mill. Feeding experiments with farm ostriches showed that bird gastroliths experience fast abrasion in the gizzard and do not develop a polish. Relative gastrolith mass in sauropods (gastrolith mass much less than 0.1% of body mass) is at least an order of magnitude less than that in ostriches and other herbivorous birds (gastrolith mass approximates 1% of body mass), also arguing against the presence of a gastric mill in sauropods. Sauropod dinosaurs possibly compensated for their limited oral processing and gastric trituration capabilities by greatly increasing food retention time in the digestive system. Gastrolith clusters of some derived theropod dinosaurs (oviraptorosaurs and ornithomimosaurs) compare well with those of birds, suggesting that the gastric mill evolved in the avian stem lineage.

A new xinjiangchelyid turtle from the Middle Jurassic of Xinjiang, China and the evolution of the basipterygoid process in Mesozoic turtles

BackgroundMost turtles from the Middle and Late Jurassic of Asia are referred to the newly defined clade Xinjiangchelyidae, a group of mostly shell-based, generalized, small to mid-sized aquatic froms that are widely considered to represent the stem lineage of Cryptodira. Xinjiangchelyids provide us with great insights into the plesiomorphic anatomy of crown-cryptodires, the most diverse group of living turtles, and they are particularly relevant for understanding the origin and early divergence of the primary clades of extant turtles.ResultsExceptionally complete new xinjiangchelyid material from the ?Qigu Formation of the Turpan Basin (Xinjiang Autonomous Province, China) provides new insights into the anatomy of this group and is assigned to Xinjiangchelys wusu n. sp. A phylogenetic analysis places Xinjiangchelys wusu n. sp. in a monophyletic polytomy with other xinjiangchelyids, including Xinjiangchelys junggarensis, X. radiplicatoides, X. levensis and X. latiens. However, the analysis supports the unorthodox, though tentative placement of xinjiangchelyids and sinemydids outside of crown-group Testudines. A particularly interesting new observation is that the skull of this xinjiangchelyid retains such primitive features as a reduced interpterygoid vacuity and basipterygoid processes.ConclusionsThe homology of basipterygoid processes is confidently demonstrated based on a comprehensive review of the basicranial anatomy of Mesozoic turtles and a new nomenclatural system is introduced for the carotid canal system of turtles. The loss of the basipterygoid process and the bony enclosure of the carotid circulation system occurred a number of times independently during turtle evolution suggesting that the reinforcement of the basicranial region was essential for developing a rigid skull, thus paralleling the evolution of other amniote groups with massive skulls.

Super sizing the giants: first cartilage preservation at a sauropod dinosaur limb joint

Re-examination of the sauropod dinosaur Cetiosauriscus greppini von Huene 1922 (Reuchenette Formation; Kimmeridgian, Late Jurassic) from northwestern Switzerland has revealed a well-preserved cartilage capsule at the distal extremity of the right humerus. The capsule represents hyaline cartilage together with fibrocartilage and can be distinguished by colour, surface structure and histology from the periosteum of the bone. This is the first fossil evidence for articular cartilage in a sauropodomorph dinosaur. It indicates the presence of a large articular capsule on sauropod forelimbs, which was only hypothesized until now, and shows that the forelimb length of sauropods was larger than previously assumed.

Dinosaur tracks from the Langenberg Quarry (Late Jurassic, Germany) reconstructed with historical photogrammetry: Evidence for large theropods soon after insular dwarfism

Here we describe dinosaur tracks from the Langenberg Quarry near Goslar (Lower Saxony) that represent the first footprints from the Late Jurassic of Germany discovered outside the Wiehen Mountains. The footprints are preserved in Kimmeridgian marginal marine carbonates. They vary in length from 36 to 47 cm and were made by theropod dinosaurs. The original tracksite with 20 footprints was destroyed by quarrying soon after its discovery in 2003. Only the five best defined footprints were excavated. Based on scanned-in analog photographs which were taken during the excavation, a three-dimensional (3-D) model of the original tracksite was generated by applying historical photogrammetry. The resulting model is accurate enough to allow a detailed description of the original tracksite. Different preservation types result from changing substrate properties and include both well-defined footprints and deeply impressed footprints with elongated heel and variably defined digit impressions. The tracksite was discovered stratigraphically close to the bone accumulation of the dwarfed sauropod dinosaur Europasaurus holgeri and probably records a sea level fall along with a faunal interchange, which would likely have eliminated the resident dwarf island fauna. The two largest and best preserved footprints differ from most other Late Jurassic theropod footprints in their great width. Two different trackmaker species might have been present at the site. Several hypotheses presented in a recent paper on Late Jurassic dinosaur tracks from the Wiehen Mountains by Diedrich (2011b) are commented upon herein. Jens N. Lallensack. Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Universität Bonn, Nussallee 8, 53115 Bonn, Germany. jens.lallensack@uni-bonn.de; P. Martin Sander. Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Universität Bonn, Nussallee 8, 53115 Bonn, Germany. m.sander@uni-bonn.de Nils Knötschke. Dinosaurier-Freilichtmuseum Münchehagen, Alte Zollstrasse 5, 31547 Rehburg-Loccum, Germany. n.knoetschke@dinopark.de Oliver Wings. Landesmuseum Hannover, Willy-Brandt-Allee 5, 30169 Hannover, Germany & Museum für Naturkunde Berlin, Invalidenstraße 43, 10115 Berlin, Germany. dr.wings@gmail.com PE Article Number: 18.2.31A Copyright: Palaeontological Association May 2015 Submission: 12 December 2014. Acceptance: 12 April 2015 Lallensack, Jens N., Sander, P. Martin, Knötschke, Nils, and Wings, Oliver. 2015. Dinosaur tracks from the Langenberg Quarry (Late Jurassic, Germany) reconstructed with historical photogrammetry: Evidence for large theropods soon after insular dwarfism. Palaeontologia Electronica 18.2.31A: 1-34 palaeo-electronica.org/content/2015/1166-langenberg-tracks LALLENSACK: LANGENBERG TRACKS

Gizzard vs. teeth, it's a tie: food-processing efficiency in herbivorous birds and mammals and implications for dinosaur feeding strategies

Abstract Particle size reduction is a primary means of improving efficiency in herbivores. The mode of food particle size reduction is one of the main differences between herbivorous birds (gizzard) and mammals (teeth). For a quantitative comparison of the efficiency of food comminution, we investigated mean fecal particle sizes (MPS) in 14 herbivorous bird species and compared these with a data set of 111 non-ruminant herbivorous mammal species. In general MPS increased with body mass, but there was no significant difference between birds and mammals, suggesting a comparable efficiency of food processing by gizzards and chewing teeth. The results lead to the intriguing question of why gizzard systems have evolved comparatively rarely among amniote herbivores. Advantages linked to one of the two food comminution systems must, however, be sought in different effects other than size reduction itself. In paleoecological scenarios, the evolution of “dental batteries,” for example in ornithopod dinosaurs, should be considered an advantage compared to absence of mastication, but not compared to gizzard-based herbivory.

Geometric morphometric analysis of intratrackway variability: a case study on theropod and ornithopod dinosaur trackways from Münchehagen (Lower Cretaceous, Germany)

A profound understanding of the influence of trackmaker anatomy, foot movements and substrate properties is crucial for any interpretation of fossil tracks. In this case study we analyze variability of footprint shape within one large theropod (T3), one medium-sized theropod (T2) and one ornithopod (I1) trackway from the Lower Cretaceous of Münchehagen (Lower Saxony, Germany) in order to determine the informativeness of individual features and measurements for ichnotaxonomy, trackmaker identification, and the discrimination between left and right footprints. Landmark analysis is employed based on interpretative outline drawings derived from photogrammetric data, allowing for the location of variability within the footprint and the assessment of covariation of separate footprint parts. Objective methods to define the margins of a footprint are tested and shown to be sufficiently accurate to reproduce the most important results. The lateral hypex and the heel are the most variable regions in the two theropod trackways. As indicated by principal component analysis, a posterior shift of the lateral hypex is correlated with an anterior shift of the margin of the heel. This pattern is less pronounced in the ornithopod trackway, indicating that variation patterns can differ in separate trackways. In all trackways, hypices vary independently from each other, suggesting that their relative position a questionable feature for ichnotaxonomic purposes. Most criteria commonly employed to differentiate between left and right footprints assigned to theropods are found to be reasonably reliable. The described ornithopod footprints are asymmetrical, again allowing for a left–right differentiation. Strikingly, 12 out of 19 measured footprints of the T2 trackway are stepped over the trackway midline, rendering the trackway pattern a misleading left–right criterion for this trackway. Traditional measurements were unable to differentiate between the theropod and the ornithopod trackways. Geometric morphometric analysis reveals potential for improvement of existing discriminant methods.

The vertebrate-bearing Late Triassic Fleming Fjord Formation of central East Greenland revisited: stratigraphy, palaeoclimate and new palaeontological data

Abstract In Late Triassic (Norian–Rhaetian) times, the Jameson Land Basin lay at 40° N on the northern part of the supercontinent Pangaea. This position placed the basin in a transition zone between the relatively dry interior of the supercontinent and its more humid periphery. Sedimentation in the Jameson Land Basin took place in a lake–mudflat system and was controlled by orbitally forced variations in precipitation. Vertebrate fossils have consistently been found in these lake deposits (Fleming Fjord Formation), and include fishes, dinosaurs, amphibians, turtles, aetosaurs and pterosaurs. Furthermore, the fauna includes mammaliaform teeth and skeletal material. New vertebrate fossils were found during a joint vertebrate palaeontological and sedimentological expedition to Jameson Land in 2012. These new finds include phytosaurs, a second stem testudinatan specimen and new material of sauropodomorph dinosaurs, including osteologically immature individuals. Phytosaurs are a group of predators common in the Late Triassic, but previously unreported from Greenland. The finding includes well-preserved partial skeletons that show the occurrence of four individuals of three size classes. The new finds support a late Norian–early Rhaetian age for the Fleming Fjord Formation, and add new information on the palaeogeographical and palaeolatitudinal distribution of Late Triassic faunal provinces.

Gastroliths in the Triassic ichthyosaur Panjiangsaurus from China

Gastroliths (stomach stones) are frequently reported in association with plesiosaur remains, especially elasmosaurids (e.g., Brown, 1904; Williston, 1904; Welles and Bump, 1949; Darby and Ojakangas, 1980; Everhart, 2000; Cicimurri and Everhart, 2001). Stones are also known from several other fossil and modern aquatic vertebrates, including fishes (Dapples, 1938; Thomson, 1966; Trewin, 1986), penguins (Emery, 1963; Stonehouse, 1967; Boswall and MacIver, 1975), crocodilians (Cott, 1961; Neill, 1971; Keller and Schaal, 1992), and pinnipeds (Fleming, 1951; Mohr, 1963; Bryden, 1999). However, gastroliths are very rarely reported in ichthyosaurs, despite the fact that a large number of articulated skeletons are known from this clade. Some ichthyosaurs show preserved gut contents (e.g., Pollard, 1968; Keller, 1976; Kear et al., 2003), and sand is occasionally found in the gastric area of ichthyosaurs (R. Wild, personal commun., 2000; Wings, personal obs.). Gastroliths with grain sizes >2 mm are only known from two specimens: the one described in detail here and a complete but undescribed skeleton from the famous Upper Jurassic Solnhofen Limestone of Germany (Taylor, 1993; Wings, personal observation). The German specimen is probably referable to the genus Nannopterygius Huene, 1922, so far only known from England. The specimen is preserved as a slab, which is on exhibit at the Jura-Museum, Eichstatt, Germany, and a counterslab, which is accessioned to the collections of the Staatliches Museum fur Naturkunde, Karlsruhe, Germany. A description of the stones found in the perfect holotype specimen (Museum of the Yichang Institute of Geology and Mineral Resources # TR00001) of Panjiangsaurus epicharis described by Chen and Cheng (2003) (Fig. 1) is important not only because of the scarcity of ichthyosaurian gastroliths, the find is also relevant for the interpretation of gastrolith function. Panjiangsaurus epicharis …

Archosaur footprints (cf. Brachychirotherium) with unusual morphology from the Upper Triassic Fleming Fjord Formation (Norian-Rhaetian) of East Greenland

Abstract The Ørsted Dal Member of the Upper Triassic Fleming Fjord Formation in East Greenland is well known for its rich vertebrate fauna, represented by numerous specimens of both body and ichnofossils. In particular, the footprints of theropod dinosaurs have been described. Recently, an international expedition discovered several slabs with 100 small chirotheriid pes and manus imprints (pes length 4–4.5 cm) in siliciclastic deposits of this unit. They show strong similarities with Brachychirotherium, a characteristic Upper Triassic ichnogenus with a global distribution. A peculiar feature in the Fleming Fjord specimens is the lack of a fifth digit, even in more deeply impressed imprints. Therefore, the specimens are assigned here tentatively to cf. Brachychirotherium. Possibly, this characteristic is related to the extremely small size and early ontogenetic stage of the trackmaker. The record from Greenland is the first evidence of this morphotype from the Fleming Fjord Formation. Candidate trackmakers are crocodylian stem group archosaurs; however, a distinct correlation with known osteological taxa from this unit is not currently possible. While the occurrence of sauropodomorph plateosaurs in the bone record links the Greenland assemblage more closer to that from the Germanic Basin of central Europe, here the described footprints suggest a Pangaea-wide exchange. Supplementary material: Three-dimensional model of cf. Brachychirotherium pes–manus set (from MGUH 31233b) from the Upper Triassic Fleming Fjord Formation (Norian–Rhaetian) of East Greenland as pdf, ply and jpg files (3D model created by Oliver Wings; photographs taken by Jesper Milàn) is available at https://doi.org/10.6084/m9.figshare.c.2133546