Supplementary data from: Decoupling of morphological disparity and taxonomic diversity during the end-Permian mass extinction

An increasing number of unexpectedly diverse benthic communities are being
reported from microbially-precipitated carbonate facies in shallow-marine
platform settings after the end-Permian mass extinction. Ostracoda, which
was one of the most diverse and abundant metazoan groups during this
interval, recorded their greatest diversity and abundance associated with
these facies. Previous studies, however, focused mainly on their taxonomic
diversity and, therefore, left room for discussion of paleoecological
significance. Here, we apply a morphometric method (semi-landmarks) to
investigate morphological variance through time to better understand the
ecological consequences of the end-Permian mass extinction, and to examine
the hypothesis that microbial mats played a key role in ostracod survival.
Our results show that taxonomic diversity and morphological disparity were
decoupled during the end-Permian extinction, and that morphological
disparity declined rapidly at the onset of the end-Permian extinction,
even though the high diversity of ostracods initially survived in some
places. The decoupled changes in taxonomic diversity and morphological
disparity suggest that the latter is a more robust proxy for understanding
the ecological impact of the extinction event, and the low morphological
disparity of ostracod faunas is a consequence of sustained environmental
stress or a delayed post-Permian radiation. Furthermore, the similar
morphological disparity of ostracods between microbialite and
non-microbialite facies indicates that microbial mats most likely
represent a taphonomic window rather than a biological refuge during the
end-Permian extinction interval.