Pulsed cephalopod diversification during the Ordovician Kröger, Björn ; Yun-Bai, Zhang Abstract Publication: Palaeogeography Palaeoclimatology Palaeoecology Pub Date: March 2009 DOI: 10.1016/j.palaeo.2008.12.015 Bibcode: 2009PPP...273..174K