First glimpse into Lower Jurassic deep-sea biodiversity: in situ diversification and resilience against extinction.
Owing to the assumed lack of deep-sea macrofossils older than the Late Cretaceous, very little is known about the geological history of deep-sea communities, and most inference-based hypotheses argue for repeated recolonizations of the deep sea from shelf habitats following major palaeoceanographic perturbations. We present a fossil deep-sea assemblage of echinoderms, gastropods, brachiopods and ostracods, from the Early Jurassic of the Glasenbach Gorge, Austria, which includes the oldest known representatives of a number of extant deep-sea groups, and thus implies that in situ diversification, in contrast to immigration from shelf habitats, played a much greater role in shaping modern deep-sea biodiversity than previously thought. A comparison with coeval shelf assemblages reveals that, at least in some of the analysed groups, significantly more extant families/superfamilies have endured in the deep sea since the Early Jurassic than in the shelf seas, which suggests that deep-sea biota are more resilient against extinction than shallow-water ones. In addition, a number of extant deep-sea families/superfamilies found in the Glasenbach assemblage lack post-Jurassic shelf occurrences, implying that if there was a complete extinction of the deep-sea fauna followed by replacement from the shelf, it must have happened before the Late Jurassic.
Natural History Museum Luxembourg, Department of Palaeontology, 24, rue Münster, Luxembourg 2160, Luxembourg nebyuht@yahoo.com.
Ben
B
Thuy
Geoscience Centre, Geobiology Group, University of Göttingen, Goldschmidtstrasse 3, Göttingen 37077, Germany.
Steffen
S
Kiel
Hungarian Natural History Museum, Department of Palaeontology and Geology, 1431 Budapest, Pf. 137, Hungary.
Alfréd
A
Dulai
School of Earth and Environmental Sciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth PO1 3QL, UK.
Andy S
AS
Gale
Natural History Museum Vienna, Department of Geology and Palaeontology, Burgring 7, Vienna 1010, Austria.
Andreas
A
Kroh
Senckenberg Research Institute, Micropalaeontology I, Senckenberganlage 25, Frankfurt 60325, Germany.
Alan R
AR
Lord
Natural History Museum Luxembourg, Department of Palaeontology, 24, rue Münster, Luxembourg 2160, Luxembourg.
Lea D
LD
Numberger-Thuy
Swedish Museum of Natural History, PO Box 50007, Stockholm 10405, Sweden.
Sabine
S
Stöhr
Senckenberg am Meer, Marine Research Department, Südstrand 40, Wilhelmshaven 26382, Germany.
Max
M
Wisshak
D000818:Animals; D001317:Austria; D044822:Biodiversity; D005075:Biological Evolution; D053476:Extinction, Biological; D005580:Fossils; D007448:Invertebrates / Q000502:physiology*; D009792:Oceans and Seas
evolution of deep-sea biota; in situ diversification; onshore-offshore patterns; resilience against extinction