Abundant new ichthyosaur material has recently been documented in the Slottsmøya Member of the Agardhfjellet Formation from the Svalbard archipelago of Norway. Here we describe a partial skeleton of a new taxon, Janusaurus lundi, that includes much of the skull and representative portions of the postcranium. The new taxon is diagnosed by a suite of cranial character states including a very gracile stapedial shaft, the presence of a dorsal process on the prearticular and autapomorphic postcranial features such as the presence of an interclavicular trough and a conspicuous anterodorsal process of the ilium. The peculiar morphology of the ilia indicates a previously unrecognized degree of morphological variation in the pelvic girdle of ophthalmosaurids. We also present a large species level phylogenetic analysis of ophthalmosaurids including new and undescribed ichthyosaur material from the Upper Jurassic of Svalbard. Our results recover all Svalbard taxa in a single unresolved polytomy nested within Ophthalmosaurinae, which considerably increases the taxonomic composition of this clade. The paleobiogeographical implications of this result suggest the presence of a single clade of Boreal ophthalmosaurid ichthyosaurs that existed during the latest Jurassic, a pattern also reflected in the high degree of endemicity among some Boreal invertebrates, particularly ammonoids. Recent and ongoing descriptions of marine reptiles from the Slottsmøya Member Lagerstätte provide important new data to test hypotheses of marine amniote faunal turnover at the Jurassic-Cretaceous boundary.

BackgroundThe best European locality for complete Eocene mammal skeletons is Grube Messel, near Darmstadt, Germany. Although the site was surrounded by a para-tropical rain forest in the Eocene, primates are remarkably rare there, and only eight fragmentary specimens were known until now. Messel has now yielded a full primate skeleton. The specimen has an unusual history: it was privately collected and sold in two parts, with only the lesser part previously known. The second part, which has just come to light, shows the skeleton to be the most complete primate known in the fossil record.Methodology/Principal FindingsWe describe the morphology and investigate the paleobiology of the skeleton. The specimen is described as Darwinius masillae n.gen. n.sp. belonging to the Cercamoniinae. Because the skeleton is lightly crushed and bones cannot be handled individually, imaging studies are of particular importance. Skull radiography shows a host of teeth developing within the juvenile face. Investigation of growth and proportion suggest that the individual was a weaned and independent-feeding female that died in her first year of life, and might have attained a body weight of 650–900 g had she lived to adulthood. She was an agile, nail-bearing, generalized arboreal quadruped living above the floor of the Messel rain forest.Conclusions/Significance Darwinius masillae represents the most complete fossil primate ever found, including both skeleton, soft body outline and contents of the digestive tract. Study of all these features allows a fairly complete reconstruction of life history, locomotion, and diet. Any future study of Eocene-Oligocene primates should benefit from information preserved in the Darwinius holotype. Of particular importance to phylogenetic studies, the absence of a toilet claw and a toothcomb demonstrates that Darwinius masillae is not simply a fossil lemur, but part of a larger group of primates, Adapoidea, representative of the early haplorhine diversification.

In spite of a fossil record spanning over 150 million years, pelvic girdle evolution in Ichthyopterygia is poorly known. Here, we examine pelvic girdle size relationships using quantitative methods and new ophthalmosaurid material from the Slottsmøya Member Lagerstätte of Svalbard, Norway. One of these new specimens, which preserves the most complete ichthyosaur pelvic girdle from the Cretaceous, is described herein as a new taxon, Keilhauia nui gen. et sp. nov. It represents the most complete Berriasian ichthyosaur known and the youngest yet described from the Slottsmøya Member. It is diagnosed on the basis of two autapomorphies from the pelvic girdle, including an ilium that is anteroposteriorly expanded at its dorsal end and an ischiopubis that is shorter or subequal in length to the femur, as well as a unique character combination. The Slottsmøya Member Lagerstätte ichthyosaurs are significant in that they represent a diverse assemblage of ophthalmosaurids that existed immediately preceding and across the Jurassic–Cretaceous boundary. They also exhibit considerable variation in pelvic girdle morphology, and expand the known range in size variation of pelvic girdle elements in the clade.

ABSTRACT. We present a synopsis of high-rank multituberculate systematics and 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 ®ve families (superfamily incertae sedis): Eucosmodontidae, Microcosmodontidae, Cimolodontidae, Bof®idae, 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 Bof®idae, might have originated from among the 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.

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Abstract:The Late Jurassic Slottsmøya Member Lagerstätte on Spitsbergen offers a unique opportunity to study the relationships between vertebrate fossil preservation, invertebrate occurrences and depositional environment. In this study, 21 plesiosaurian and 17 ichthyosaur specimens are described with respect to articulation, landing mode, preservation, and possible predation and scavenging. The stratigraphic distribution of marine reptiles in the Slottsmøya Member is analysed, and a correlation between high total organic content, low oxygen levels, few benthic invertebrates and optimal reptile preservation is observed. A new model for 3D preservation of vertebrates in highly compacted organic shales is explained.

A Mongolian ankylosaurid specimen identified as Norge, Postboks 73, Norway; Tom E. Guldberg [tguldberg@miswaco.com ], Fossekleiva 9, Norway; Jørn H. Hurum [j.h.hurum@nhm.uio.no]