Publications - Published papers

Please find below publications of our group. Currently, we list 501 papers. Some of the publications are in collaboration with the group of Sonja Prohaska and are also listed in the publication list for her individual group. Access to published papers (access) is restricted to our local network and chosen collaborators. If you have problems accessing electronic information, please let us know:

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

Loïc Villier and Gunther J. Eble

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Paleobiology, 30, 652–665. (2004)

Abstract


he joint quantification of disparity and diversity is an important aspect of recent macroevolutionary studies, and is usually motivated by theoretical considerations on 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 address this issue in the context of the radiation of the echinoid order Spatangoida during the Cretaceous. We compare patterns at the genus- and species-level, 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. Different morphometric methods, however, produce somewhat different signals early in the radiation. 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. Notwithstanding, a general deceleration in morphological diversification is apparent at both the genus and the species level. Moreover, inclusion or exclusion of the sister-order Holasteroida and stem-group Disasteroida in the reference morphospace did not affect proportional changes in spatangoid disparity. The relative robustness of these patterns implies that the choice of temporal scale, morphometric scheme, and taxonomic level may not substantially affect the representation of large-scale morphospace structure and of broad trends in disparity. However, the choice need not be arbitrary, as particular questions may demand certain protocols.