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Assessing the robustness of disparity estimates; the impact of morphometric scheme, temporal scale, and taxonomic level in spatangoid echinoids

Loic Villier and Gunther J. Eble
Assessing the robustness of disparity estimates; the impact of morphometric scheme, temporal scale, and taxonomic level in spatangoid echinoids
Paleobiology (2004) 30 (4): 652-665

Abstract

The quantification of disparity is an important aspect of recent macroevolutionary studies, and it is usually motivated by theoretical considerations about the pace of innovation and the filling of morphospace. In practice, varying protocols of data collection and analysis have rendered comparisons among studies difficult. The basic question remains, How sensitive is any given disparity signal to different aspects of sampling and data analysis? Here we explore this issue in the context of the radiation of the echinoid order Spatangoida during the Cretaceous. We compare patterns at the genus and species levels, with time subdivision into subepochs and into stages, and with morphological sampling based on landmarks, traditional morphometrics, and discrete characters. In terms of temporal scale, similarity of disparity pattern accrues despite a change in temporal resolution, and a general deceleration in morphological diversification is apparent. Different morphometric methods also produce similar signals. Both the landmark analysis and the discrete character analysis suggest relatively high early disparity, whereas the analysis based on traditional morphometrics records a much lower value. This difference appears to reflect primarily the measurement of different aspects of overall morphology. Disparity patterns are similar at both the genus and species levels. Moreover, inclusion or exclusion of the sister order Holasteroida and the stem group Disasteroida in the sampled morphospace did not affect proportional changes in spatangoid disparity. Similar results were found for spatangoid subclades vis-a-vis spatangoids as a whole. The relative robustness of these patterns implies that the choice of temporal scale, morphometric scheme, and taxonomic level may not affect broad trends in disparity and the representation of large-scale morphospace structure.


ISSN: 0094-8373
EISSN: 1938-5331
Coden: PALBBM
Serial Title: Paleobiology
Serial Volume: 30
Serial Issue: 4
Title: Assessing the robustness of disparity estimates; the impact of morphometric scheme, temporal scale, and taxonomic level in spatangoid echinoids
Affiliation: Universitaet zu Berlin, Institut fuer Palaeontologie, Berlin, Federal Republic of Germany
Pages: 652-665
Published: 2004
Text Language: English
Publisher: Paleontological Society, Lawrence, KS, United States
References: 43
Accession Number: 2005-024982
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: illus. incl. 2 tables
Secondary Affiliation: Universitaet Leipzig, DEU, Federal Republic of Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200510
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