The annulated orthoceridans of the Middle and Late Ordovician of Baltoscandia are described and their systematic frame is revised. The revision of these nautiloids, which are part of the Orthocerida and Pseudorthocerida, is based on the investigation of characters of the septal neck, the siphuncular tube, and the apex. An unequivocal terminology of these characters is suggested and applied. The...

BACKGROUND Sphaerexochinae is a speciose and widely distributed group of cheirurid trilobites. Their temporal range extends from the earliest Ordovician through the Silurian, and they survived the end Ordovician mass extinction event (the second largest mass extinction in Earth history). Prior to this study, the individual evolutionary relationships within the group had yet to be determined uti...

-The Ordovician Radiation exhibited a global transition in dominance from the Cambrian evolutionary fauna (e.g., trilobites), to the Paleozoic and Modern faunas (e.g., articulate brachiopods and bivalve molluscs). Although its causes have yet to be determined definitively, the transition coincided with increased global tectonism. Erosion of source areas uplifted during orogenic activity increas...

Klonowska, I. 2017. Deep subduction of the Seve Nappe Complex in the Scandinavian Caledonides. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1595. 63 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-513-0139-6. This thesis seeks to improve our understanding of the processes involved in continental collision zones, with a particular f...

The strata in the Shita Mountain, Yunkai region, are predominantly composed of clastic rocks with intercalated limestones. However, precise stratigraphic age remains uncertain due to scarcity fossils. Previously, conglomerate layers this region were considered indicative Yunan Orogeny during Cambrian–Ordovician transition. through identification 12 lithofacies types and 5 combinations Mountain ...