Daniela Schwarz

A nearly complete skeleton of an early juvenile diplodocid (Dinosauria: Sauropoda) from the Lower Morrison Formation (Late Jurassic) of north central Wyoming and its implications for early ontogeny and pneumaticity in sauropods

A nearly complete skeleton of a juvenile sauropod from the Lower Morrison Formation (Late Jurassic, Kimmeridgian) of the Howe Ranch in Bighorn County, Wyoming is described. The specimen consists of articulated mid-cervical to mid-caudal vertebrae and most appendicular bones, but cranial and mandibular elements are missing. The shoulder height is approximately 67 cm, and the total body length is estimated to be less than 200 cm. Besides the body size, the following morphological features indicate that this specimen is an early juvenile; (1) unfused centra and neural arches in presacral, sacral and first to ninth caudal vertebrae, (2) unfused coracoid and scapula, (3) open coracoid foramen, and (4) relatively smooth articular surfaces on the limb, wrist, and ankle bones. A large scapula, short neck and tail and elongate forelimb bones relative to overall body size demonstrate relative growth. A thin-section of the mid-shaft of a femur shows a lack of annual growth lines, indicating an early juvenile individual possibly younger than a few years old. Pneumatic structures in the vertebral column of the specimen SMA 0009 show that pneumatisation of the postcranial skeleton had already started in this individual, giving new insights in the early ontogenetic development of vertebral pneumaticity in sauropods. The specimen exhibits a number of diplodocid features (e.g., very elongate slender scapular blade with a gradually dorsoventrally expanded distal end, a total of nine dorsal vertebrae, presence of the posterior centroparapophyseal lamina in the posterior dorsal vertebrae). Although a few diplodocid taxa, Diplodocus, cf. Apatosaurus, and cf. Barosaurus, are known from several fossil sites near the Howe Ranch, identification of this specimen, even at a generic level, is difficult due to a large degree of ontogenetic variation.

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.

The first dentary of Lisboasaurus (Crocodylomorpha, ?Mesoeucrocodylia) from the Lower Cretaceous (Barremian) of Uña, Cuenca Province, Spain

Lisboasaurus is a small-sized and poorly understood crocodylomorph from the Upper Jurassic (Kimmeridgian) Guimarota fossil locality in Portugal (Buscalioni et al., 1996; Schwarz and Fechner, 2004). The holotype for the type species L. estesi is an incomplete right maxilla with one in situ tooth. Referred material of L. estesi is restricted to a maxillary fragment and a box of isolated teeth (Milner and Evans, 1991; Buscalioni et al., 1996; Schwarz and Fechner, 2004). In his original descriptions, Seiffert (1970, 1973) erected two species, L. estesi and L. mitracostatus, for material from Guimarota. Because L. mitracostatus was based on extremely fragmentary cranial material of both lacertilians and crocodylomorphs, it was considered a nomen dubium for a long time (Milner and Evans, 1991; Buscalioni et al., 1996). A recent revision of the crocodylomorphs from Guimarota transferred the crocodylomorph specimens originally attributed to L. mitracostatus to the genus Lusitanisuchus (Schwarz and Fechner, 2004), which left L. estesi as the only valid species of Lisboasaurus. The phylogenetic relationships of Lisboasaurus have long been debated. Lisboasaurus originally was described as an anguimorph lacertilian (Seiffert, 1970, 1973), but this interpretation was later questioned (Estes, 1983). Lisboasaurus next was interpreted as an archosaurian, most probably a maniraptoran theropod (Milner and Evans, 1991). Most recently, a phylogenetic analysis placed Lisboasaurus within the clade of mesoeucrocodylian crocodylomorphs (Buscalioni et al., 1996). Recently, an incomplete crocodylomorph dentary with in situ teeth virtually identical to those of Lisboasaurus estesi was identified in collections from the Lower Cretaceous Spanish locality of Uña (Fig. 1). This find extends the spatial and temporal range of Lisboasaurus considerably. Even more importantly, this first known dentary of Lisboasaurus increases our knowledge about the cranial morphology of this taxon, which currently is diagnosed exclusively by maxillary characters, and supports assigning Lisboasaurus to the Crocodylomorpha. The objectives of this paper are to describe this new dentary, provide a revised diagnosis for Lisboasaurus, and discuss how the new dentary furthers our understanding of the genus. The Uña locality is an abandoned coal mine in the village of Uña, in east-central Spain (Fig. 1). The sediments of the coal mine belong to the Barremian age Uña Formation, which is an alternating sequence of limestones and vertebrate fossil-bearing, lignite-coal lenses that are interstratified with marls (GierlowskiKordesch and Janofske, 1989; Brinkmann, 1992). The beds are interpreted to be limnic and fluviatile in origin and to have been deposited under warm, seasonal climatic conditions (GierlowskiKordesch and Janofske, 1989; Schudack, 1989; Brinkmann, 1992). The fossil vertebrate assemblage from Uña includes fish, amphibians, lacertilians, crocodylomorphs, dinosaurs, and mammals (Henkel and Krebs, 1969; Brinkmann, 1992; Kriwet, 1999; Rauhut, 2002). Fossils reported in this paper are housed in the Paleontology Section, Institute of Geological Sciences, Freie Universität Berlin (IPFUB), in Berlin, Germany.