The rise and fall of Late Devonian (Frasnian) trilobites from Belgium: taxonomy, biostratigraphy and events
Van Viersen, A.P.; Vanherle, W. (2018). The rise and fall of Late Devonian (Frasnian) trilobites from Belgium: taxonomy, biostratigraphy and events. Geol. Belg. 21(1-2): 73-94. https://dx.doi.org/10.20341/gb.2018.005
In: Geologica Belgica. Geologica Belgica: Brussels . ISSN 1374-8505; e-ISSN 2034-1954, more
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Trilobites; systematic palaeontology; palaeoecology; palaeobiogeography;extinctions |
| Authors | | Top |
- Van Viersen, A.P.
- Vanherle, W.
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| Abstract |
Trilobites are recorded from Frasnian strata in Belgium on the basis of old museum collections and contemporary fieldwork. Of the four third-order Transgressive-Regressive (T-R) cycles recognised here in the latest Givetian to late Frasnian, the last three are each associated with a version of a largely coherent, acastid–scutelluid dominated trilobite fauna. Accents of this “base” fauna encompassed probably primarily allochthonous elements. The timing and effects of the late Frasnian Kellwasser Event in Belgium differ according to fossil group and their position along the ramp. The new data from this study are suggestive of distinct extinction patterns for the trilobite associations of the reefal environments and lateral facies. No evidence was identified for a direct impact of the Kellwasser levels on the Belgian trilobite fauna, although not a single trilobite is known with certainty from strata above the base of the Lower Kellwasser level. Comparisons to trilobite faunas from other countries are suggestive of open, shallow-water migration routes between southern Laurussia and peri-Gondwana during most of the Frasnian. New taxa are Bradocryphaeus echinatus sp. nov., Magreanops renateae gen. & sp. nov. (both Moulin Liénaux Formation), Bradocryphaeus laomedeia sp. nov., Bradocryphaeus neptuni hottonensis ssp. nov., Cyphaspis koimeterionensis sp. nov. (all Grands Breux Formation), Magreanops monachus gen. & sp. nov., Quadratispina excelsa sp. nov. (both Bovesse Formation) and Pterocoryphe platymarginata sp. nov. (Champ Broquet Formation). Magreanops gen. nov. represents the first and only known big-eyed phacopid from Frasnian strata worldwide, breaching the established latest Givetian to late Famennian gap of this group. |
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