Abstract
Trilobite diversity patterns; implications for paleobiological analysis
Abstracts with programs - Geological Society of America, Vol.29(6), p.31
Geological Society of America, 1997 annual meeting
1997
Abstract
Trilobite diversity is examined in light of a comprehensive and critically evaluated compilation of all known Ordovician through Wenlock genera. Using a timescale composed of ten Ordovician stage/subseries divisions and five Silurian stages, all genera are scored for presence/absence in each sampling interval. This allows the tabulation of diversity curves based upon both raw occurrence and occurrence explicitly corrected for the effects of Lazarus taxa. In addition, the identification and compilation of subjective synonyms, based upon our standardized specialist opinion, permits an estimate of the significant effects of taxonomic practice and malpractice on patterns derived from large scale clade compilations. A parallel study compiles all available data on within-habitat (alpha) diversity during the same interval, using a generalized environmental model.The result yields a cumulative global diversity curve with relative slope broadly comparable to that derived from previous more coarsely resolved clade compilations. This cumulative curve, however, is not similar to that derived for any single monophyletic subgroup of trilobites, at any taxonomic level. That is, the overall diversity curve is largely divorced from the pattern represented by any of its natural components. Potential reasons for this are explored, but an important implication is that raw taxon counts may require qualification before use as proxies for macroevolutionary dynamics. Such qualification can only be accomplished through knowledge of the hierarchical relationships within the dataset. In the case of taxa, these relationships are phylogenetic, and hence it is necessary to interpret clade compilations within the constraints imposed by their phylogenetic structure. A second surprising result is that the pattern of global clade diversity is essentially independent from that of alpha diversity. While there was apparently significant change through time in standing clade diversity, this was barely registered at the community level, as the number of trilobite species in most major environments remained generally constant through the study interval. This is particularly significant in the case of the end-Ordovician mass extinctions; while higher diversity was culled by approximately half, within-habitat diversity was unaffected.
Details
- Title: Subtitle
- Trilobite diversity patterns; implications for paleobiological analysis
- Creators
- Jonathan M Adrain - Natural History Museum, Department of Palaeontology London GBR United KingdomRichard A ForteyStephen R Westrop
- Resource Type
- Abstract
- Publication Details
- Abstracts with programs - Geological Society of America, Vol.29(6), p.31
- Conference
- Geological Society of America, 1997 annual meeting
- Publisher
- Geological Society of America (GSA)
- ISSN
- 0016-7592
- Alternative title
- Geological Society of America, 1997 annual meeting
- Language
- English
- Date published
- 1997
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984240905502771
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