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| Titel |
The Miocene Cyprideis species flock (Ostracoda; Crustacea) of western Amazonia (Solimões Formation) |
| VerfasserIn |
Martin Gross, Maria Ines F. Ramos, Werner E. Piller  |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250107283
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| Publikation (Nr.) |
 EGU/EGU2015-6976.pdf |
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| Zusammenfassung |
| The Miocene mega-wetland of western Amazonia holds a diverse, largely endemic aquatic
invertebrate fauna (e.g., molluscs, ostracods). Among ostracods, the genus Cyprideis
experienced a remarkable radiation. Micropalaeontologic investigations of a 400-m-long
sediment core (~62 km SW Benjamin Constant, Amazonia, Brazil) permitted a taxonomic
revision of about two-thirds of hitherto described Cyprideis species. Ostracod index species
enabled a biostratigraphic allocation of the well succession to the Cyprideis minipunctata to
Cyprideis cyrtoma biozones (late middle to early late Miocene age). The current study
underlines once more Cyprideis’ remarkable capability to produce species flocks and western
Amazonian Cyprideis comply with the criteria of a species flock: i) endemicity: up to now
not a single species is recorded in adjacent areas; ii) monophyly: although hardly
verifiable to date and probably Amazonian Cyprideis is not monophyletic s.str., several
closely related, quite rapidly evolving species are proved; iii) speciosity: due to the
present study, 30 formally described species exist; several further species, left in
open nomenclature, are recorded in the literature, which strongly hints to a much
higher, still unrecorded species richness; iv) ecological diversity: based on rare
sedimentologic cross-references, ecological diversity within a highly structured wetland
is possible; the current results demonstrate the sympatric occurrence of up to 12
Cyprideis species, which may indicate adaptations to different microhabitats; v) habitat
dominance: regularly Cyprideis holds more than >90 % in western Amazonian ostracod
assemblages during the early and middle Miocene. Explanations for this extreme habitat
monopolisation are still arguable and touch the highly disputed question about the
nature of western Amazonia‘s environments during the Miocene. It seems, however,
evident that a strictly actualistic approach to endemic Neogene Amazonian biota is
highly problematic. This study was funded by Austrian Science Fund (FWF project
P21748-N21). |
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