caa a22 4500 386384770 CHVBK 20180307112055.0 cr unu---uuuuu 161130s1989 xx s 000 0 eng 10.1017/S0263593300028716 doi S0263593300028716 pii (NATIONALLICENCE)cambridge-10.1017/S0263593300028716 Morris S. Conway Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, U.K. The persistence of Burgess Shale-type faunas: implications for the evolution of deeper-water faunas [Elektronische Daten] [S. Conway Morris] Discoveries, most of them recently, in more than thirty Lower and Middle Cambrian horizons with soft-bodied fossils have shown that forty-one of the genera occur also in the celebrated Burgess Shale (Middle Cambrian). Significantly, they tend to have lengthy stratigraphic durations which together encompass an interval from the early Lower Cambrian (Tommotian) to near the end of the Middle Cambrian. At least some genera have also wide geographical ranges, with occurrences around much of the Laurentian (N America) craton, and also in N and S China, Australia, Siberia, Spain and Poland. Although a few genera, e.g. Isoxys, may have been pelagic, for the most part these distributions are explained in terms of a deeper-water biota with an evolutionarily conservative aspect. Both the origins and further recruitment to this biota may have been from shallower water, with more limited in situ diversification. It is speculated that this distinctive Cambrian biota was gradually driven to extinction with the arrival of Ordovician competitors, although some relics may have survived until at least the Devonian. This history has implications for our understanding of deeper-water faunas throughout the Phanerozoic, and supports the notion that archaic forms may take refuge in this environment. Copyright © Royal Society of Edinburgh 1989 Cambrian nationallicence Lagerstätten nationallicence migration nationallicence Transactions of the Royal Society of Edinburgh: Earth Sciences Royal Society of Edinburgh Scotland Foundation 80/3-4(1989), 271-283 0263-5933 80:3-4<271 1989 80 TRE https://doi.org/10.1017/S0263593300028716 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0263593300028716 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Morris S. Conway Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, U.K NATIONALLICENCE 773 0- Transactions of the Royal Society of Edinburgh: Earth Sciences Royal Society of Edinburgh Scotland Foundation 80/3-4(1989), 271-283 0263-5933 80:3-4<271 1989 80 TRE CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge