How disastrous was Oceanic Anoxic Event 2? A shelf versus deep-sea comparison from the echinoderm perspective
Final Report Abstract
By late Aptian/Albian times, deep-sea echinoderm assemblages of modern composition were distributed globally rather than restricted to the North Atlantic, which was confirmed due to the fact that all investigated early Cretaceous sites showed typical representatives of deep-sea echinoderm families (especially Ophiuroidea and Holothuroidea), which are also well-known from today. Although the South (e.g., Falkland Plateau) and North Atlantic (e.g., Blake Nose) share most taxa – indicative of faunal exchange between the areas – some asteroid families and ophiuroid genera are lacking in the North Atlantic assemblage. This clearly demonstrates that the slightly younger South Atlantic echinoderm assemblages recruited its taxonomic inventory not only by southward migration of North Atlantic forms, but guests from other areas (Pacific?) immigrated also. Furthermore, the last major re-organisation of deep-sea echinoderm communities predates all Cretaceous Oceanic Anoxic Events. In fact, the Hauterivian (lower Lower Cretaceous) brittle star fauna from the Lower Exmouth Plateau (off NW Australia) shows a co-occurrence of ophiacanthid and ophiolepidid brittle stars, which is typical of modern bathyal ophiuroid communities. As the Hauterivian assemblage from the Indian Ocean predates all Cretaceous Oceanic Anoxic Events (OAEs), our suggested hypothesis was verified. Therefore, the immigration of modern-type deep-sea echinoderm assemblages must be located even in pre-Hauterivian times. This, on the other hand, raises the question, whether OAEs were disastrous for deep-sea echinoderms at all and if, how disastrous these sensible deep-sea communities were truly affected. The occurrence of atelostomate echinoid spines in deep-sea sediments since the latest Early Cretaceous (Albian) shows that the Atelostomata (Echinoidea) resisted all palaeoceanographic perturbations. There is no evidence that OAEs impacted the Atelostomata diversity at all. Interestingly, from the Upper Cretaceous to the Mid-Miocene (no younger data available so far), atelostomate echinoids dominated the deep-sea, while other Echinodermata were apparently scarce to absent. This pattern is anactualistic compared to the recent dominance especially of sea cucumbers (Holothuroidea) and brittle stars (Ophiuroidea) in the deep sea. When the ‘true’ modern-style deep-sea echinoderm assemblage established remains still unclear. Spiegel Online: http://www.spiegel.de/wissenschaft/natur/tiefsee-lebewesen-im-atlantik-forscher-entdecken-lebende-fossiliena-860602.html Science ORF: http://science.orf.at/stories/1706226/ N-TV: http://www.n-tv.de/wissen/Tiefsee-Tiere-aelter-als-gedacht-article7443576.html WDR 5: http://www.wdr5.de/sendungen/leonardo/s/d/11.10.2012-16.05/b/lebensraum-tiefsee-extrem-aber-vor-katastrophen-sicherer.html
Publications
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(2012): Ancient Origin of the Modern Deep-Sea Fauna. PLoS ONE 7 (10): 1-11
Thuy, B.; Gale, A. S.; Kroh, A.; Kucera, M.; Numberger-Thuy, L. D.; Reich, M. & Stöhr, S.
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(2012): Late Cretaceous phymosomatids and the true identity of Cidarites granulosus Goldfuss, 1829 (Echinoidea, Phymosomatoida). Zootaxa 3271: 17-30
Schlüter, N.; Kutscher, M.; Smith, A. B., Jagt, J. W. M. & Lees, J. A.
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(2012): On Mesozoic laetmogonid sea cucumbers (Echinodermata: Holothuroidea: Elasipodida). Zoosymposia 7: 185-212
Reich, M.
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(2013): How many species of fossil holothurians are there ? [In:] Johnson, C. (ed.): Echinoderms in a Changing World. Proceedings of the 13th International Echinoderm Conference, University of Tasmania, Hobart Tasmania, Australia, 5-9 January 2009: 23-51, Boca Raton (CRC Press)
Reich, M.
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(2013): Temporary expansion to shelf depths rather than an onshore-offshore trend: the shallow-water rise and demise of the modern deep-sea brittle star family Ophiacanthidae (Echinodermata: Ophiuroidea). European Journal of Taxonomy 48: 1-242
Thuy, B.
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(2014): Santonian sea cucumbers (Echinodermata: Holothuroidea) from Sierra del Montsec, Spain. Göttingen Contributions to Geosciences 77: 147-160
Reich, M. & Ansorge, J.
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(2014): Shallow-water brittle-star (Echinodermata: Ophiuroidea) assemblage from the Aptian (Early Cretaceous) of the North Atlantic: first insights into bathymetric distribution patterns. Göttingen Contributions to Geosciences 77: 163-182
Thuy, B.; Gale, A. S.; Stöhr, S. & Wiese, F.
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(2015): Systematic assessment of the Atelostomata (Spatangoida and Holasteroida; irregular echinoids) based on spine microstructure. Zoological Journal of the Linnean Society 175 (3): 510-524
Schlüter, N.; Wiese, F. & Reich, M.
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(2017): First report of sea cucumbers (Echinodermata: Holothuroidea) from the latest Cretaceous of Bavaria, Germany. Zitteliana 89: 285-289
Reich, M.
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(2017): Molecular phylogeny of extant Holothuroidea (Echinodermata). Molecular Phylogenetics and Evolution 111: 110-131
Miller, A.K.; Kerr, A.M.; Paulay, G.; Reich, M.; Wilson, N.G.; Carvajal, J.I. & Rouse, G.W.
