1 Biogeography of early to mid Palaeozoic (Cambrian–Devonian) marine 2 phytoplankton 3 Stewart G. Molyneux 1*, Aurélien Delabroye 2, 3, 4 Reed Wicander 4 & Thomas Servais 2 5 1 British Geological Survey, Keyworth, Nottingham NG12 5GG, U.K. 6 (e-mail:
[email protected]) 7 2 UMR 8217 Géosystèmes, CNRS-Université de Lille1, Cité Scientifique, 59655 8 Villeneuve d’Ascq Cedex, France 9 (e-mail:
[email protected]) 10 3 Ichron Limited, Century House, Gadbrook Business Centre, Northwich, Cheshire, 11 CW9 7TL U.K. (email:
[email protected]) 12 4 Department of Geology, Central Michigan University, Mt. Pleasant, MI 48859, 13 U.S.A. (e-mail:
[email protected]) 14 *Corresponding author 15 16 Text: 30,435 words (including references and figure/table captions) 17 References: 336 (10,193 words) 18 Tables: 2 19 Figures: 12 20 Abbreviated title: Palaeozoic phytoplankton biogeography 21 22 Abstract: Early to mid Palaeozoic marine phytoplankton are represented by 23 acritarchs and associated forms, which had a global distribution from the early 24 Cambrian to the early Carboniferous (Mississippian). Palaeozoic phytoplankton 25 assemblages show varying degrees of cosmopolitanism and endemism through time. 26 A high degree of cosmopolitanism was evidently characteristic of the Cambrian and 27 much of the Late Ordovician, Silurian and Devonian, but provincialism was more 28 marked in the Early Ordovician and Hirnantian (latest Ordovician), the latter at a time 29 of major palaeoenvironmental perturbations. Distribution patterns of Palaeozoic 30 phytoplankton are attributed to a number of interacting factors, including 1 31 palaeolatitude, palaeotemperature, oceanic circulation patterns, the disposition of 32 continents, differentiation between oceanic and more cratonic (distal–proximal) 33 assemblages, and sedimentary environments and facies.