Search

Phylogenetic relationships within the important ichthyosaur family Ophthalmosauridae are not well established, and more specimens and characters, especially from the postcranial skeleton, are needed. Three ophthalmosaurid specimens from the Tithonian (Late Jurassic) of the Slottsmøya Member Lagerstätte on Spitsbergen, Svalbard, are described. Two of the specimens are new and are referred to Keilhauia sp. and Ophthalmosauridae indet. respectively, whereas the third specimen consists of previously undescribed basicranial elements from the holotype of Cryopterygius kristiansenae. The species was recently synonymized with the Russian Undorosaurus gorodischensis, but despite many similarities, we conclude that there are too many differences, for example in the shape of the stapedial head and the proximal head of the humerus; and too little overlap between specimens, to warrant synonymy on species level. A phylogenetic analysis of Ophthalmosauridae is conducted, including all Slottsmøya Member specimens and new characters. The two proposed ophthalmosaurid clades, Ophthalmosaurinae and Platypterygiinae, are retrieved under some circumstances, but with little support. The synonymy of three taxa from the Slottsmøya Member Lagerstätte with Arthropterygius is not supported by the present evidence. [ABSTRACT FROM AUTHOR]

Phylogenetic relationships within the important ichthyosaur family Ophthalmosauridae are not well established, and more specimens and characters, especially from the postcranial skeleton, are needed. Three ophthalmosaurid specimens from the Tithonian (Late Jurassic) of the Slottsmøya Member Lagerstätte on Spitsbergen, Svalbard, are described. Two of the specimens are new and are referred to Keilhauia sp. and Ophthalmosauridae indet. respectively, whereas the third specimen consists of previously undescribed basicranial elements from the holotype of Cryopterygius kristiansenae. The species was recently synonymized with the Russian Undorosaurus gorodischensis, but despite many similarities, we conclude that there are too many differences, for example in the shape of the stapedial head and the proximal head of the humerus; and too little overlap between specimens, to warrant synonymy on species level. A phylogenetic analysis of Ophthalmosauridae is conducted, including all Slottsmøya Member specimens and new characters. The two proposed ophthalmosaurid clades, Ophthalmosaurinae and Platypterygiinae, are retrieved under some circumstances, but with little support. The synonymy of three taxa from the Slottsmøya Member Lagerstätte with Arthropterygius is not supported by the present evidence. [ABSTRACT FROM AUTHOR]

The palaeontology of the Lower to Middle Triassic succession in Spitsbergen has been studied for more than a century and a half. Our ability to properly interpret the evolutionary and ecological implications of the faunas requires precise stratigraphic control that has only recently become available. Within such a detailed stratigraphic framework, the Spitsbergen fossil material promises to contribute to our understanding of the faunal recovery after the end-Permian mass extinction. [ABSTRACT FROM AUTHOR]

We report on the discovery of large cephalopod arm hooks (mega-onychites) from the Kimmeridgian and Volgian of Spitsbergen (Agardhfjellet Formation). This includes a largely uncompressed hook in a seep carbonate,with preservation of surface sculpture. We suggest the use of logarithmic spirals as morphological descriptors for the outer part of cephalopod arm hooks, with implications for systematics and functional morphology. Comparison with Upper Jurassic material from Greenland, northern Norway and the North Sea demonstrates a remarkably consistent morphology, which we assign to the same form species, Onychites quenstedti. Considering the relatively small stratigraphic (Kimmeridgian- Volgian) and biogeographic (Boreal) range of this large form, it is likely that it represents a single biological species or genus. [ABSTRACT FROM AUTHOR]

A Mongolian ankylosaurid specimen identified as Tarchia gigantea is an articulated skeleton including dorsal ribs, the sacrum, a nearly complete caudal series, and in situ osteoderms. The tail is the longest complete tail of any known ankylosaurid. Remarkably, the specimen is also the first Mongolian ankylosaurid that preserves impressions of the keratinous scales overlying the bony osteoderms. This specimen provides new information on the shape, texture, and arrangement of osteoderms. Large flat, keeled osteoderms are found over the pelvis, and osteoderms along the tail include large keeled osteoderms, elongate osteoderms lacking distinct apices, and medium-sized, oval osteoderms. The specimen differs in some respects from other Tarchia gigantea specimens, including the morphology of the neural spines of the tail club handle and several of the largest osteoderms. [ABSTRACT FROM AUTHOR]

Two samples of a vertebra and a jawbone from two specimens of the Upper Jurassic Pliosaurus funkei from Spitsbergen have been described with respect to findings of fluorescing inclusions of liquid petroleum hosted in mineral precipitates representing a former primary skeletal porosity. Analyses were undertaken to elucidate potential animal and/or petroleum derivation(s) of the fluid(s) and possibly the timing of infilling with respect to the burial history of the hosting Pliosaurus. The fluid inclusion temperatures of homogenisation range from 47 to 117 °C. The earliest trapped fluids are primary aqueous inclusions occurring in calcite and barite close to the boundary to the skeletal matrix, followed by (or penecontemporaneously with) isolated, bluish-fluorescing, primary petroleum inclusions in vicinity of the aqueous fluid inclusions in barite. These inclusions homogenise at the highest measured temperatures. Subsequently trapped hydrocarbons homogenise at lower temperatures as their density increases. Such observations of decreasing API (increasing density) with decreasing temperature may be related to secondary changes in migrated petroleum during earlier documented uplift at Spitsbergen. Biomarkers reflect a depositional condition for the Upper Jurassic shales, i.e., the source rock expelling petroleum was potentially the rock occurring just below the Pliosaurus-bearing strata. In addition to inclusions validating a petroleum origin, a few low-viscosity, reddish- brown colored inclusions, not likely to represent a bituminous liquid, are observed, potentially of an animal origin. [ABSTRACT FROM AUTHOR]

Ichthyosaur diversity near the Jurassic-Cretaceous boundary, particularly from high paleolatitudes, is poorly known. Two recently collected specimens of medium- to large-bodied ichthyosaurs from the Slottsmøya Member of the Agardhfjellet, Svalbard, Norway represent two new taxa of ophthalmosaurids. The holotype specimen of Cryopterygius kristiansenae gen et sp. nov., PMO 214.578, is a nearly complete and largely articulated skeleton. The specimen consists of a nearly complete skull, the entire presacral and preflexural vertebral series, numerous dorsal ribs and gastralia, an articulated pectoral girdle and nearly complete forelimb, and an articulated left pelvic girdle and hindlimb. The new taxon is diagnosed on a unique suite of features, including a robust and moderately elongate rostrum, a reduced supranarial process, an elongate maxilla that bears a high number of teeth, the absence of a lacrimal-external naris contact, and an anteroposteriorly broad postorbital bar possessing an unidentified element (supratemporal?) that lies posterior to the quadratojugal. Cryopterygius has 52 presacral vertebrae, a distinctive forelimb, including a humerus that bears only two facets at its distal end, and an articulated left pelvic girdle and hindlimb, which facilitates the unequivocal orientation of the ophthalmosaurid femur. The holotype specimen of Palvennia hoybergeti, SVB 1451, includes a nearly complete skull and fragmented postcranial remains. It is diagnosed on its relatively short rostrum, greatly enlarged orbit, narrow postorbital bar, very large pineal foramen, basioccipital with broad extracondylar area laterally, and a gracile stapedial shaft. The Slottsmøya Lagerstätte is established as one of the most productive horizons for Upper Jurassic ichthyosaurs and considerably expands our knowledge of ophthalmosaurid diversity and distribution in the latest Jurassic. [ABSTRACT FROM AUTHOR]

Paleontological fieldwork on Spitsbergen, 2004-2011, has revealed the presence of abundant plesiosaur and ichthyosaur remains, a series of 15 seep carbonate bodies, as well as a rich invertebrate fauna from the Upper Jurassic - Lower Cretaceous Slottsmoya Member of the Agardhfjellet Formation, a 70-100 metre-thick unit of dark grey to black shale and paper shale. Deposition of the Slottsmoya Member occurred at high paleolatitudes, at or near the Arctic Circle, and molluscan and foraminiferal biostratigraphy indicates an Early Volgian - Ryazanian age for the unit. In this volume we present the organic carbon isotope chemostratigraphy, cyclostratigraphy, lithostratigraphy and sedimentology for the Member. A well preserved assemblage of fossil echinoderms, the first ultrastructural information on the lingulid brachiopod Lingularia and microfacies of nine seep carbonatesare described. Comparative analyses of the marine reptile material found in the Slottsmoya Member indicate a diverse assemblage of new plesiosaurians (two new genera and three new species of plesiosauroids and one new species of pliosaurid) and ichthyosaurians (two new genera and species). Placed within a high-resolution stratigraphic framework, the diverse invertebrate and vertebrate assemblage of the Slottsmoya Lagerstatte provides an unparallelled opportunity to study the evolution and paleoecology of a high-latitude, Mesozoic, marine ecosystem. [ABSTRACT FROM AUTHOR]

Eight seasons of fieldwork in the Upper Jurassic black shales of the Slottsmoya Member of the Agardhfjellet Formation (Upper Jurassic; Middle Volgian) in the Arctic archipelago of Svalbard have yielded numerous skeletal remains of plesiosaurs and ichthyosaurs. Among the new discoveries from the Slottsmoya Member are two very large specimens of short-necked plesiosaurians. Dental and postcranial morphology suggest that they represent a new species of the genus Pliosaurus, a taxon known from several specimens of Kimmeridgian and Tithonian-aged strata in England, France and Russia. Skeletal dimensions of this new taxon suggest that it was one of the largest members of the Pliosauridae and that it possessed comparatively longer front limbs than other known pliosaurids. A morphometric analysis of pliosaurids indicates they had a wide range of interspecific variability in relative paddle lengths compared to body size. [ABSTRACT FROM AUTHOR]

At present, our knowledge of plesiosauroid diversity from the uppermost Jurassic (Tithonian/Volgian) is very limited. Newly discovered material from the Slottsmoya Member of the Agardhfjellet Formation of central Spitsbergen, Svalbard, contributes significant new information on this poorly known interval and helps bridge a temporal gap between better known plesiosaurians from the older Jurassic deposits of Europe, and Cretaceous of North America. The partially articulated skeleton of a juvenile long-necked plesiosaurian, PMO 216.839, is one of the most complete plesiosaur fossils known from Spitsbergen and represents a new taxon, Djupedalia engeri gen. et sp. nov. Whilst sharing some similarities with previously described taxa from the Oxford Clay (Muraenosaurus, Tricleidus, and Cryptoclidus) and the Kimmeridge Clay formations (Kimmerosaurus) of England, the new taxon can be diagnosed by features of the cervical vertebrae, including centrum proportions and morphology, a very pronounced posterior shift in the neural spines relative to the centrum, fused prezygapophyses and greatly elongated postzygapophyses, as well as extremely short dorsal neural spines and femora that are longer than the humeri. The new taxon can also be distinguished from other newly-described plesiosauroids from Svalbard, thus indicating that several plesiosaurian taxa existed at high paleolatitudes during the Late Jurassic. [ABSTRACT FROM AUTHOR]

At present, very little is known regarding the diversity and morphological disparity of long-necked plesiosaurs in Tithonian-aged (latest Jurassic) units globally. Here, we describe two species of a new, long-necked plesiosaur genus Spitrasaurus from the Upper Jurassic Slottsmøya Member of the Agardhfjellet Formation on Svalbard. The holotype species of the genus, S. wensaasi, is the most complete long-necked specimen found in this unit to date and is readily diagnosed on the basis of having at least 60 cervical vertebrae possessing a prominent lateral longitudinal ridge, as well as the presence of a column of well-developed preaxial accessory ossicles in the limbs. A second taxon, S. larseni, includes a partial skull that broadly resembles the Kimmeridgian taxon Kimmerosaurus, but differs in the morphology of its basioccipital, and in having a distinctive lower jaw with a greatlyelongate and strongly dorsally inflected retroarticular process, among other characteristics. Each species of Spitrasaurus can be differentiated on the basis of cervical vertebral proportions and in the morphology of the cervical ribs, rib facets and neural arches, in addition to being stratigraphically separated. The high number of cervical vertebrae in Spitrasaurus significantly exceeds that for described Middle to Late Jurassic plesiosaurs, but is comparable to some Cretaceous elasmosaurids. The Middle Volgian age of this material helps to bridge the temporal and morphological gap between better known Middle and Late Jurassic plesiosaurians from Europe and Late Cretaceous taxa primarily known from North America. [ABSTRACT FROM AUTHOR]

A partial postcranial plesiosaurian skeleton uncovered on Svalbard in the winter of 1930-31 was described and named Tricleidus svalbardensis Persson, 1962. However, the precise geographic location and stratigraphic unit in which the skeleton was found were not published. Recent fieldwork on Svalbard has uncovered two more plesiosaur skeletons that are demonstrated herein to be conspecific with the 1931 taxon. These new specimens, along with recently discovered historic documents produced by the excavation members of the 1930-31 expedition, reveal that the holotype specimen, PMO A 27745, was recovered from the Upper Jurassic Slottsmoya Member of the Agardhfjellet Formation, which is Middle Volgian in age. Collectively, the Svalbard material is neither morphologically nor stratigraphically consistent with the Callovian taxon Tricleidus Andrews, 1909 and is here referred to Colymbosaurus Seeley, 1874 from the Kimmeridge Clay Formation (Kimmeridgian to Tithonian) of the UK. [ABSTRACT FROM AUTHOR]

A new discovery of ornithopod dinosaur tracks from Svalbard is described. The Lower Cretaceous (Barremian) section at Isfjorden consists of sandstones and interbeds consistent with an alluvial flood plane. The newly discovered tracks are situated on two different horizons stratigraphically below the original horizon found in 1960. Footprint evidence from Festningen and Kvalvågen suggests that during the Early Cretaceous there was a diverse dinosaur fauna on Svalbard and that both theropods and ornithopods were present at the time. [ABSTRACT FROM AUTHOR]

We present a synopsis of high-rank multituberculate systematicsand a manually generated cladogram illustrating multituberculate interrelationships. We divide the Multituberculata into the paraphyletic suborder 'Plagiaulacida', an apparently monophyletic suborder Cimolodonta, and one family incertae sedis. Within 'Plagiaulacida' we recognise three informal lines: paulchoffatiid (three families), plagiaulacid (three families) and allodontid (two families and the genus Glirodon). The Cimolodonta are divided into an informal Paracimexomys group; three superfamilies: Ptilodontoidea, Djadochtatherioidea (new), and Taeniolabidoidea (restricted to Taeniolabididae); and five families (superfamily incertae sedis): Eucosmodontidae, Microcosmodontidae, Cimolodontidae, Boffiidae, and Kogaionidae; and some genera incertae sedis. New characters used in our analysis are (1) a tendency of molar cusps to coalesce; and (2) ornamentation of grooves, pits, and ridges on the molars. We argue that the Ptilodontoidea, and less certainly also the Cimolodontidae and Boffiidae, might have originated from amongthe plagiaulacid line, a possible intermediate link being the Paracimexomys group. The remaining Cimolodonta might have originated from unknown members of the Paracimexomys group with separated molar cusps and smooth enamel. The origin of two types of prismatic enamel and a relationship between them are stumbling blocks in understanding the origin of the Cimolodonta; we conclude that microprismatic enamel made its appearance only once. Revised diagnoses of high-rank multituberculate taxa, including lists of all known genera, are given. [ABSTRACT FROM AUTHOR]