No abstract

The palaeobiogeographical distribution of the six major clades of Ordovician echinoderms (asterozoans, blastozoans, crinoids, echinozoans, edrioasteroids and stylophorans) is analysed based on a comprehensive and up-to-date database compiling 3701 occurrences (1938 species recorded from 331 localities) of both complete specimens and isolated ossicles. Although historically biased towards a limited number of regions (Europe, North America, Russia), the resulting dataset makes it possible to identify six main palaeobiogeographical provinces for Ordovician echinoderms: Laurentia, Baltica, West Gondwana, East Gondwana, Avalonia and Siberia. At a global scale, the high endemicity of echinoderms during the Early to Middle Ordovician coincides with the time of maximum dispersal of continental masses. Late Ordovician faunas tend to become more cosmopolitan, possibly as a consequence of changing palaeogeography and/or relatively higher sea-levels in the Sandbian–Katian interval. Regional biodiversity patterns of Ordovician echinoderms confirm that their major diversification during the Ordovician is not a single, universal evolutionary event, but rather results from the complex addition of contrasted local evolutionary trends.

No abstract

No abstract

Papers sent to me by the authors have greatly facilitated the co mpilation of this volume and I extend my sincere appreciation to all of you. Crinoid specialists who sent lists of their publications for 1981-1 985 are al�. o kindly c:cknov;ledged as it helped ob:ain some papers via interlibrary loan. Special appreciation is extended to Wen Yang and Qi Cheng Fan for tra11slation of th0 papers by Mu and Lin (1 982; 1983) a:1d Yannjisusuo (1 983). Yu. A. Arendt and '/. G. Klikushin corrected my transliteraticns of some Russian titles. Yuli1 Liao, Gilbert Klapper, John Watkinson, and Pius Weibel provided or helped obtain CO;lies of some papers that I could not obtain by interlib;ary loan. Help of the interlibary loan staff of Washington State Univorsity and the library staff of the Geology Library d! the University of Indiana is gratefully acknowledged. Debbie Marsh kindly upgraded my use of the word processor and Dottie Howell graciously ran copies of the drafts.