Silurian graptolites from Washington Land, western North Greenland

Abstract

Fifty-six graptolite species and subspecies are described from the Silurian sediments of Washington Land and Hall Land, western North Greenland. The graptolite faunas indicate the following ages and zones: Middle Llandovery, the argenteus and convolutus Zones; Upper Llandovery, the turriculatus and spiralis Zones; probably the Llandovery to Wenlock transition; Lower Wenlock, the riccartonensis Zone; Uppermost Wenlock (?) and Lower Ludlow. The bulk of the graptolite species are well known, but some new minor morphological grades are recognised. Four new species and one new subspecies Pseudoclimacograptus (Clinoclimacograptus)? washingtoni, Plectograptus? intermedius, Monograptus kochi, Monograptus teicherti,– and Monograptus bjerringus schucherti – are erected. P. (C.)? washingtoni and P.? intermedius possess morphological characters which are referable to more than one previously described subgenus and genus. The retiolitid fills a gap in the known record of the retiolitids.