Occurrences of Psigraptus and Chigraptus gen. nov. in the Tremadoc of the Yukon Territory, Canada

• Published in: Geological Magazine
• Main Authors: JACKSON, D. E., LENZ, A. C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1999
• Subjects: Peel River; Yukon
• Online Access: http://dx.doi.org/10.1017/s0016756899002332; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756899002332

The full stratigraphical context of the type materials of Psigraptus arcticus and P. lenzi from Rock River are given, as well as a new occurrence of the Psigraptus–Adelograptus Zone in the Upper Canyon, Peel River of Canada's Yukon Territory. A new monotypic genus Chigraptus is created for a quadriradiate anisograptid graptolite with four unbranched first-order stipes, a horizontal to slightly reclined rhabdosome and isolate autothecae. The genus is found only at the base of the Early Tremadoc Anisograptus–Staurograptus Zone. Chigraptus may have given rise to the Late Tremadoc Psigraptus by a reduction in first-order stipes and by increased reclination.