Late Ordovician (Hirnantian) shelly fossils from New Zealand and their significance

Miospore assemblages from Late Ordovician (Katian-Hirnantian), Ghelli Formation, Alborz Mountain Range North-eastern Iran: Palaeophytogeographic and palaeoclimatic implications

Well-preserved miospore assemblages are recorded from the Late Ordovician (Katian-Hirnantian), Ghelli Formation in Pelmis-gorge at the north-eastern Alborz Mountain The palynomorphs were extracted from siliciclastic deposits which are well-dated by using of marine palynomorphs (acritarchs and chitinozoans). The encountered miospore assemblages consist of 14 genera (28 species: 26 cryptospores a...

structure of tropical seas during the Late Ordovician Hirnantian glaciation Lipid biomarkers record fundamental changes in the microbial community

The Late Ordovician mass extinction was linked to climate cooling and glaciation of Gondwana during the terminal Ordovician Hirnantian Age (444.7–443.4 Ma). Extinction patterns have been well described for many marine taxa, but much less is known about marine microbial communities through this interval. To elucidate the structure of microbial communities in tropical marine basins through the La...

Cyanobacterial fossils from 252 Ma old microbialites and their environmental significance

The end-Permian mass extinction was followed by the formation of an enigmatic rock layer with a distinctive macroscopic spotted or dendroid fabric. This deposit has been interpreted as microbial reef rock, digitate dendrolite, digital thrombolite, dendritic thrombolite, or bacterial deposits. Agreement has been reached in considering them as microbialites, but not in their formation. This study...

Notes on the Ordovician Fossils from Bear Island Collected Du Ring the Swedish Expeditions

D uring his Arctic Expedition in the summer of 1898 A. G. NATHORST 1 succeeded in finding fossils in a limestone of the socalled Heclahook-system of Bear Island, the small inlet lying iso1ated between Norway and Spitzbergen, at about 7 41/2 o N. L. (see map p. 91 ). This Heclahook-system consists of a series of limestone, dolomite, quartzitic sandstone and shale, folded and generally very much ...

SR/SR isotopic curve for the mid-Cincinnatian (Upper Katian–Lower Hirnantian, Upper Ordovician), NE North American Shelf (Ontario, Canada) transition to the Hirnantian glaciation