Late Albian adaptive radiation in the calcareous nannofossil genus Eiffellithus

Well preserved nannofossil assemblages in upper Albian and lower Cenomanian hemipelagic sections from Ocean Drilling Program (ODP) Leg 171B preserve a record of the early history and adaptive radiation of the genus Eiffellithus. Seven distinct taxa are recognized and differentiated, with one previou...

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Bibliographic Details
Published in:Micropaleontology 2003-09, Vol.49 (3), p.231-251
Main Authors: Watkins, David K, Bergen, James A
Format: Article
Language:English
Subjects:
Adaptive radiation
Albian
Albian age
algae
assemblages
Atlantic Ocean
biogeography
biologic evolution
Biological taxonomies
Biostratigraphy
Blake Nose
Blake Plateau
correlation
Cretaceous
Eiffellithus
Eiffellithus equibiramus
Eiffellithus parvus
Eiffellithus praestigium
Eiffellithus vonsalisiae
Ellipses
Extinct species
First appearance datums
Holotypes
Leg 171B
Lower Cretaceous
marine environment
Mesozoic
microfossils
nannofossils
new taxa
North Atlantic
Ocean Drilling Program
ODP Site 1050
ODP Site 1052
paleo-oceanography
paleoecology
pelagic environment
Plantae
range
revision
Stover
Stratigraphy
Taxa
taxonomy
upper Albian
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Description
Summary:Well preserved nannofossil assemblages in upper Albian and lower Cenomanian hemipelagic sections from Ocean Drilling Program (ODP) Leg 171B preserve a record of the early history and adaptive radiation of the genus Eiffellithus. Seven distinct taxa are recognized and differentiated, with one previously named taxon (E. monechiae) emended and four new species described: E. praestigium, E. vonsalisiae, E. equibiramus, and E. parvus. Sample census data indicate that most species evolved, rose to dominance, and then rapidly declined to extinction, to be replaced by other members of the genus. Newly evolved species tended to remain at low abundance levels until a significant disruption in the pelagic realm resulted in the precipitous decline of the dominant species. This decline provided open niche space in the pelagic realm into which the new species could rapidly rise to dominance. These major disruptions correspond to significant changes or shifts in the sedimentological and carbon isotopic records associated with the late Albian Oceanic Anoxic Event (OAE-1d), suggesting that major changes in the strength of deep mixing and the structure of the surface water mass drove the early adaptive radiation of Eiffellithus.
ISSN:0026-2803
1937-2795
DOI:10.2113/49.3.231