Abstract
Silurian trilobite alpha diversity and the end-Ordovician extinction
Abstracts with programs - Geological Society of America, Vol.30(7), p.285
Geological Society of America, 1998 annual meeting
1998
Abstract
A new data set of 126 collections yielding 25,000 trilobites, mostly from Laurentia, eastern Avalonia, and Baltica, provides a record of within-habitat (alpha) species diversity during the Silurian through a spectrum of shelf environments. The end-Ordovician extinction had surprisingly little impact on long-term alpha diversity trends in Laurentia: apart from a brief drop in the Ordovician-Silurian boundary interval, the number of trilobite species in local habitats between the Llandovery and the Ludlow remained at levels no lower than those of both the Late Cambrian and the Middle Ordovician. Recovery from the end-Ordovician event was achieved well before the end of the Llandovery. Laurentian trilobite alpha diversity during each series of the Silurian is not significantly different from levels for shelf habitats in other parts of the world. An earlier analysis of the Ordovician of Laurentia is now supplemented by a dataset of Middle and Late Ordovician collections from other paleocontinents. These data confirm that Laurentian and global patterns are in broad agreement: collections from eastern Avalonia, Armorica, Baltica, and South China indicate shelf trilobite alpha diversity as high or higher than those of Laurentia. The apparent stability of species alpha diversity is particularly surprising in view of the long-term Ordovician-Silurian decline in global taxonomic richness of trilobites, which resulted in a total number of genera for the Early Silurian (Wenlock) that was only 40% of the number in the Middle Ordovician (Whiterock). This decline must be a consequence of large scale controls on diversity, such as a reduction in levels of provinciality among trilobites in the Late Ordovician. The results of the analysis affirm the need for a hierarchical approach to the analysis of diversity in the fossil record.
Details
- Title: Subtitle
- Silurian trilobite alpha diversity and the end-Ordovician extinction
- Creators
- Jonathan M Adrain - Natural History Museum, Department of Palaeontology London GBR United KingdomStephen R Westrop - Oklahoma Museum of Natural History USA United StatesBrian D. E Chatterton - University of AlbertaLars Ramskold - University of Uppsala SWE Sweden
- Resource Type
- Abstract
- Publication Details
- Abstracts with programs - Geological Society of America, Vol.30(7), p.285
- Conference
- Geological Society of America, 1998 annual meeting
- Publisher
- Geological Society of America (GSA)
- ISSN
- 0016-7592
- Alternative title
- Geological Society of America, 1998 annual meeting
- Language
- English
- Date published
- 1998
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984240912602771
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