Early Tremadocian (Ordovician) graptolite biostratigraphy and correlation

A revision of the early Tremadocian graptolites of the genus Rhabdinopora shows that Rhabdinopora proparabola from the Xiaoyang-qiao section, Dayangcha, North China is the oldest species of the genus. Early Tremadocian species of Rhabdinopora can be differentiated easily by the construction of their nemata. The earliest species, Rhabdinopora proparabola, lacks a nema, while a multibranched nema is present in Rhabdinopora campanulatum (= Rhabdinopora parabola). The Rhabdinopora proparabola, Rhabdinopora campanulatum, Rhab-dinopora flabelliformis (Anisograptus matanensis Biozone) and Rhabdinopora anglica biozones can be correlated worldwide. A short inter-val at the base of the Ordovician System does not contain any planktic graptolites.(c) 2022 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights reserved.