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Mats Eriksson

Mats Eriksson

Professor

Mats Eriksson

Diversification and biogeography of scolecodont-bearing polychaetes in the Ordovician

Author

  • Olle Hints
  • Mats Eriksson

Summary, in English

Scolecodonts are common microfossils in Palaeozoic rocks, bearing witness to the extensive radiation of jawed polychacte worms during the Ordovician Period. Information on Ordovician scolecodonts is increasing, though it is still patchy and strongly skewed towards Baltica and Laurentia. Comparison of the faunas of these two palaeocontinents indicates that approximately 50% of the genera, but only a few species, had intercontinental distribution. Meagre data from other terranes also show that several genera were cosmopolitan. In total, more than 50 Ordovician genera are known. The first records are from the Furongian (latest Cambrian), but scolecodont diversity and abundance remained very low until the Darriwilian. The earliest jawed polychaetes had primitive, usually symmetrical, placognath/ctenognath type jaw apparatuses. Xanioprionids, tetraprionids? and/or conjungaspids seem to have played an important role in the early evolution and diversification of scolecodont-beating polychactes. The first more advanced taxa, such as the polychaetaspids with labidognath type jaw apparatuses and mochtyellids with placognath type apparatuses and compound maxillae, are first recorded in the earliest Mid Ordovician. The most significant increase in global generic diversity, but also regional species-level diversity, occurred in the late Mid Ordovician, when many common taxa appeared. Accordingly, the origination rate is highest in that interval. Since many Ordovician polychaete genera are relatively long-ranging, extending into the Silurian, the extinction rate is low throughout the Period, increasing only slightly in the latest Late Ordovician. The normalised diversity curve is characterised by an increasing trend in the Mid Ordovician, followed by a plateau in the Late Ordovician. (c) 2006 Elsevier B.V. All rights reserved.

Department/s

  • Lithosphere and Biosphere Science

Publishing year

2007

Language

English

Pages

95-114

Publication/Series

Palaeogeography, Palaeoclimatology, Palaeoecology

Volume

245

Issue

1-2

Document type

Journal article

Publisher

Elsevier

Topic

  • Geology

Keywords

  • polychaete jaws
  • scolecodonts
  • palaeobiogeography
  • Ordovician
  • diversification

Status

Published

ISBN/ISSN/Other

  • ISSN: 1872-616X