Abstract
Regional Silurian trilobite turnover coincident with graptolite mass extinction
Abstracts with programs - Geological Society of America, Vol.32(7), p.367
Geological Society of America, 2000 annual meeting
2000
Abstract
Recent work has established that alpha (within-habitat) diversity of trilobites was relatively unaffected by the great end-Ordovician mass extinction. In fact, deep subtidal trilobite alpha diversity reached an all time peak during the Wenlock. However, it is clear that trilobites began to decline soon after. Latest Silurian and Devonian trilobite assemblages are of markedly decreased diversity, and increasingly restricted to only local abundance. The nature and causes of this decline are not well understood. It has long been recognized that graptolites experienced a major mass extinction during the late Wenlock (Homerian), often termed the "lundgreni event". Cyrtograptids became extinct, while monograptids and plectograptids were severely culled. Previously, no turnover of benthic shelly animals has been recognized at this event. Evidence from the Cape Phillips Fm. of Arctic Canada reveals a significant extinction and turnover of trilobites, coincident with the pelagic lundgreni event. Six trilobite genera present in the northern Laurentia became globally extinct, other major clades disappeared permanently from the northern Laurentian record, and the generic composition of succeeding trilobite faunas was significantly altered. Post-extinction trilobite faunas show an immediate and sustained drop in alpha diversity of about 50 percent, and no known faunas worldwide return to pre-lundgreni levels. It may be that the ultimate decline of trilobites was precipitated by this previously undetected extinction event.
Details
- Title: Subtitle
- Regional Silurian trilobite turnover coincident with graptolite mass extinction
- Creators
- Jonathan M Adrain - University of Iowa
- Resource Type
- Abstract
- Publication Details
- Abstracts with programs - Geological Society of America, Vol.32(7), p.367
- Conference
- Geological Society of America, 2000 annual meeting
- Publisher
- Geological Society of America (GSA)
- ISSN
- 0016-7592
- Alternative title
- Geological Society of America, 2000 annual meeting
- Language
- English
- Date published
- 2000
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984240883702771
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