There are a number of fundamental problems in assessing the astronomically forced cyclostratigraphy of the Jurassic Period. First, Jurassic geochronology is not well constrained, due to a general scarcity of radiometric dates, inferior precision of the existing ones, and large inaccuracies in stratigraphic constraints. These problems are particularly troublesome in the Early to Middle Jurassic ...

The tectonic assembly of the Northern Cordillera is currently disputed and directly impacts Paleozoic-to-recent paleogeographic plate reconstructions North America. In this study, we present new U-Pb zircon geochronology from allochthonous Yukon-Tanana terrane parautochthonous Cassiar south-central Yukon, Canada. Our data provide constraints for in region. Metasedimentary samples Ingenika Group...

Sauropodomorph dinosaurs originated in the Southern Hemisphere in the Middle or Late Triassic and are commonly portrayed as spreading rapidly to all corners of Pangaea as part of a uniform Late Triassic to Early Jurassic cosmopolitan dinosaur fauna. Under this model, dispersal allegedly inhibited dinosaurian diversification, while vicariance and local extinction enhanced it. However, apomorphy-...

Flower, enclosed ovule and tetrasporangiate anther are three major characters distinguishing angiosperms from other seed plants. Morphologically, typical flowers are characterised by an organisation with gynoecium and androecium surrounded by corolla and calyx. Theoretically, flowers are derived from their counterparts in ancient ancestral gymnosperms. However, as for when, how and from which g...

study of plant macrofossils of jurassic sediments of shemshak group in eshkevarat-e-olia areas led to identification of two species consisting lobifolia rotundifolia from ferns group (division pteridophyta & filicales order) and ptilophyllum vasekgahense from gymnospermae group (division cycadophyta & order bennettitales) that had been reported from rhaetian (late triassic) and dogger (middle j...

The Upper Jurassic to Lower Cretaceous shallow water platform carbonates of the Northern Calcareous Alps (Plassen Formation, “Lärchberg Formation”) and the resedimented deposits of the latter within basinal series (Barmstein Limestone, Tressenstein Limestone) are currently under re-investigation (SCHLAGINTWEIT et al., 2003; GAWLICK et al., 2005). This shallow water development is directly linke...

We describe a range of triconodont mammalian teeth from the Forest Marble (Middle Jurassic) of Kirtlington Quarry (Oxfordshire), Watton Cliff, and Swyre (both Dorset), and demonstrate the presence of a variety of morganucodontans, including Morganucodon tardus sp. n., Cherwellia leei gen. et sp. n., and Stylidens hookeri gen. et sp. n. “Amphilestidae” are represented by three species, Phascolot...

To ascertain the Early-to-Middle Jurassic tectonic setting in central Great Xing’an Range, this study investigated Early and Middle granitoids exposed Chaihe area Range based on isotopic chronology petrogeochemistry. The results of show that have emplacement ages 179–172 Ma. Moreover, are high-K calc-alkaline unfractionated I-type fractionated granitoids, respectively. magma sources both origin...