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1 September 2011 Diversity Dynamics of Callovian-Albian Brachiopods in the Northern Caucasus (Northern Neo-Tethys) and a Jurassic/Cretaceous Mass Extinction
Dmitry A. Ruban
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Abstract

The fossil records of the Northern Caucasus (southwestern Russia) provide an exceptional opportunity to reveal the evolution of brachiopods during the Callovian-Albian time interval and to evaluate the regional evidence for a Jurassic/Cretaceous mass extinction. Stratigraphic ranges of 119 species, 52 genera, 25 families, 13 superfamilies, and 2 orders of brachiopods are considered to document the main patterns of their diversity dynamics. The total number of taxa was high in the Callovian-Oxfordian, then dropped in the Kimmeridgian, increased again in the Tithonian, decreased significantly in the Berriasian, and remained relatively low until the end of the Early Cretaceous except for a minor peak in the Barremian. Species, genera, families, and superfamilies of brachiopods declined remarkably in the Northern Caucasus in the Berriasian, which is regional evidence for a Jurassic/Cretaceous mass extinction. Both an acceleration in disappearance rate and a drop in appearance rate contributed to this collapse. Recovery began in the Valanginian-Hauterivian, but it was not completed at the level of species. Transgressions/regressions, growth of the carbonate platform, a salinity crisis, and oxygen depletion were important controls on the brachiopod diversity dynamics in the Northern Caucasus. A regressive episode around the Jurassic-Cretaceous transition seems to be a plausible cause of the relevant brachiopod decline. A comparison of changes in the total number of brachiopod taxa between the Neo-Tethys Ocean and the Alpine Tethys Ocean shows some difference, but both domains provide evidence for a Jurassic/Cretaceous mass extinction, which was less severe in the Swiss Alps and the Jura Mountains (Alpine Tethys) than in the Northern Caucasus (Neo-Tethys).

© by the Palaeontological Society of Japan
Dmitry A. Ruban "Diversity Dynamics of Callovian-Albian Brachiopods in the Northern Caucasus (Northern Neo-Tethys) and a Jurassic/Cretaceous Mass Extinction," Paleontological Research 15(3), 154-167, (1 September 2011). https://doi.org/10.2517/1342-8144-15.3.154
Received: 5 May 2010; Accepted: 1 May 2011; Published: 1 September 2011
JOURNAL ARTICLE
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KEYWORDS
Alpine Tethys
Brachiopods
diversity dynamics
Early Cretaceous
Late Jurassic
mass extinction
Middle Jurassic
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