Chapter 27 Cambrian–Ordovician cephalopod palaeogeography and diversity

Abstract

AbstractCephalopods have their earliest occurrence in Late Cambrian shallow-water carbonates on the North China Platform and rapidly dispersed across the globe within the latest Cambrian. Latest Cambrian and initial Ordovician cephalopod occurrences are restricted to the palaeotropical realm. The Ordovician records a unique morphological diversification and expansion of cephalopod habits and habitats which is expressed in a massive morphological diversification and unique palaeogeographical patterns of dispersal. The Ordovician cephalopod diversification was a complex process of appearance and disappearance of higher groups with a specific palaeogeographical signature and a clear selective component. A general Ordovician trend showed decreasing evolutionary turnover rates, increasing number of widespread genera, decreasing proportion of endemic genera, and decreasing beta-diversity. This is interpreted as a result of an increasing ecosystem stability during this time interval.