Article: Isolated graptolites from the Llandovery of Kallholen, Sweden

A graptolite fauna of Monograptus argenteus Biozone age (Aeronian = Middle Llandovery), chemically isolated from limestone nodules formerly thought to be of M. turriculatus Biozone age (Telychian = Upper Llandovery), is described. The total fauna comprises Metadimacograptus hughesi (Nicholson), Glyptograptus aff. incertus Rickards, G. sinuatus sinuatus (Nicholson), Clinoclimacograptus retroversus Bulman and Rickards, Agetograptus primus Obut and Sobolevskaya, Agetograptus sp., ' Orthograptus' cyperoides (Tornquist), 'O.' insectiformis (Nicholson), Monoclimacis sp., Pristiograptus concinnus (Lapworth), Pribylo-graptus leptotheca (Lapworth), Monograptus communis communis Lapworth, M. denticulatus sensu Sudbury, M. millepeda M'Coy and Rastrites peregrinus Barrande. Spines are recognized for the first time on the thecae of M. c. communis and M. millepeda. It is suggested that M. lobiferus evolved from M. millepeda which had itself evolved from M. c. communis. The generic diagnosis for Pribylograptus Obut and Sobolevskaya is emended, as the existing diagnosis for the genus is based upon a misinterpretation of the thecal structure derived from examination of pyrite internal moulds.