Showing papers by "Stephen McLoughlin published in 2008"

Seed ferns survived the end-cretaceous mass extinction in Tasmania

Abstract: Seed ferns, dominant elements of the vegetation in many parts of the world from the Triassic to Cretaceous, were considered to have disappeared at the end of the Cretaceous together with several other groups that had occupied key positions in terrestrial and marine ecosystems such as dinosaurs, plesiosaurs, and ammonoids. Seed-fern demise is generally correlated with competition from diversifying flowering plants through the Cretaceous and the global environmental crisis related to the Chicxulub impact event in the paleotropics at the end of the period. New fossils from Tasmania show that one seed-fern lineage survived into the Cenozoic by at least 13 million years. These fossils are described here as a new species, Komlopteris cenozoicus. Komlopteris is a genus of seed ferns attributed to Corystospermaceae and until now was not known from sediments younger than the Early Cretaceous. Discovery of this "Lazarus taxon," together with the presence of a range of other relictual fossil and extant organisms in Tasmania, other southern Gondwanan provinces, and some regions of northern North America and Asia, underscores high-latitude regions as biodiversity refugia during global environmental crises and highlights their importance as sources of postextinction radiations.

Early Jurassic annelid cocoons from eastern Australia

Abstract: A small assemblage of clitellate annelid cocoons (egg cases) is described from the Early Jurassic Marburg Subgroup, Clarence-Moreton Basin, eastern Australia. Two complete specimens are preserved on bedding planes, and numerous fragments were recovered from organic residues prepared for mesofossil analysis. The complete specimens are assigned to Burejospermum Krassilov emend. Manum, Bose & Sawyer, 1991, having a well-developed mesh-like hapsine and a solid layer of underlying alytine. The fragments include a form assigned to Dictyothylakos Horst, 1954 emend. Manum, Bose & Sawyer, 1991 having a mesh-like hapsine but lacking an alytine layer. The cocoons are preserved in floodbasin facies represented by leaf-rich, dark shales. Palynological data indicate a Pliensbachian to earliest Toarcian age for the assemblage. Similarities between the new specimens, congeneric material from the Triassic to Neogene of other continents, and modern egg cases highlight the long-term morphological conservatism of clitellate ...