Sandbian [SEP] named after
Sandbian
The Sandbian is the first stage of the Upper Ordovician. It follows the Darriwilian and is succeeded by the Katian. Its lower boundary is defined as the first appearance datum of the graptolite species "Nemagraptus gracilis" around million years ago. The Sandbian lasted for about 5.4 million years until the beginning of the Katian around million years ago.
Naming.
The name Sandbian is derived from the village Södra Sandby (Lund Municipality, Skåne County, Sweden). The name was proposed in 2006.
GSSP.
layered connecting rings. Cameral deposits are prevalent and concentrated more ventrally. The apex is small and spherical and lacks a cicatrix.
The Lituitida, which were originally included in the Tarphycerida as the Lituitidae (Furnish and Glenister) have their beginnings in the Early Ordovician with forms like "Ancistroceras". Their diversity increased after the late Arenigian extinction (Floian-Dapingian) at the end of the Canadian Epoch and take a tumble following the early Cincinnatian (Sandbian) in the early Late Ordovician, from which the group never recovers