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Silurian (Ludlow) acastid trilobites from Gotland and Scania,Sweden |
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| Authors: | Lars Ramsköld Stockholm Gregory D Edgecombe |
| Institution: | 1. Sektionen f?r Palaeozoologi, Naturhistoriska Riksmuseet, Box 50007, S-10405, Stockholm, Sweden 2. Department of Historical Geology & Palaeontology, University of Uppsala, Norbyv?gen 22, S-75236, Uppsala, Sweden 3. Department of Geology, University of Alberta, T6G 2E3, Edmonton, Canada 4. Division of Earth Sciences, Australian Museum, P.O. Box A285, NSW 2000, Sydney South, Australia |
| Abstract: | Acastid trilobites from Ludlow strata on Gotland include three stratigraphically non-overlapping species ofAcastella Reed:Acastella madidipes n. sp. (Hemse Marl and Eke Beds),A. breviceps (Angelin 1851) (Burgsvik Beds), andA. amatrix n. sp. (Hamra Beds, and probably Burgsvik Beds). Type and other material ofA. breviceps (Angelin) from the Klinta Formation, Scania, is revised. Meraspid and early holaspid material ofAcastella is described. Some characters supportAcaste and allied taxa of mostly Wenlock age as a monophyletic subfamily Acastinae.Acastella as widely recognized is a grade with Devonian species more closely related to Asteropyginae than to the Ludlow type species. Baltic Ludlow-P?00ED;dolí species previously placed inScotiella Delo form a distinct group,Ewacaste n. gen., that includes a species from the uppermost Eke Beds on Gotland. |
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