Isolated graptolites from the Telychian (upper llandovery, Silurian) of Latvia and Estonia

Abstract

Isolated material of 21 graptolite species from the upper Telychian of Latvia and Estonia is described. New thecal structures are recognized in Streptograptus, for example enrolment of the disto-lateral margin of the flange in distal S. nodifer thecae, possession of proximal lobes in S. wimani and elongated proximal lobes in sp. 3. spp. 1 and 2 both possess a nozzle, but do not have coiled metathecae. Thecal asymmetry in Oktavites falx is shown to be the reverse of that in O. spiralis. Several new Streptograptus and Monoclimacis species remain to be described. The absence of many of the taxa described herein from Silurian equatorial regions strengthens the case for a distinct equatorial graptolite province. © 2006 The Palaeontological Association.