DOI: 10.5061/dryad.7gg70
title: Data from: Evenness and diversity in Upper Cambrian – Lower Ordovician trilobite communities from the Central Andean Basin (Cordillera Oriental, Argentina)

description: Community evenness has recently received much attention, either because it
 is related to ecosystem functioning or because it may affect estimation of
 diversity. Temporal and environmental trends in diversity and evenness of
 trilobite communities during the Late Cambrian – Early Ordovician of the
 Cordillera Oriental (north-western Argentina) are here analysed. Richness
 and evenness increase through time in both deep subtidal (between
 fair-weather and storm wave base) and offshore (below storm wave base)
 communities. Two significant patterns are superimposed on this general
 trend: (1) the magnitude of the increase in evenness is much more
 pronounced in deep than in shallower settings, and (2) richness and
 evenness trajectories are decoupled (while a significant rise in evenness
 is recorded in the middle Tremadocian (Tr2), an increase in richness is
 delayed until the late Tremadocian (Tr3)). In contrast to expectations, a
 single family (Olenidae) is dominant in samples associated with this
 earlier rise in evenness relative to richness. Hence, this trend is
 explained neither by the number of families present in the communities nor
 by the familial identity of the most abundant taxon. Large-scale
 comparisons of the timing and geographical components of these trends are
 restricted to the patterns recognized in Laurentian North American
 studies. Results from the Cordillera Oriental mirror those of Laurentia
 regarding the rise in both metrics in deep marine settings. Nevertheless,
 the timing of this increase in richness and evenness is delayed in the
 Cordillera Oriental, supporting the idea that palaeogeographical regions
 differed in the nature and timing of ecological changes. Finally, the rise
 in trilobite alpha-diversity through the Late Cambrian – Early Ordovician
 of the Cordillera Oriental supports the idea that trilobite
 alpha-diversity did not decline worldwide, suggesting that the relative
 decline in trilobite alpha-diversity is most probably caused by the
 dilution effect.
description: Tremadocian 3
 datasetAbundance dataset.
 Samples were collected from restricted 10-20 cm shale intervals.
 Localities and depositional environments are indicated. Individuals were
 counted using the MNI protocol. The dataset was taxonomically standardized
 by the authors.Tr3.csvFloian 1 datasetAbundance dataset. Samples were collected from restricted 10-20 cm shale intervals. Localities and depositional environments are indicated. Individuals were counted using the MNI protocol. The dataset was taxonomically standardized by the authors.Fl1.csvFloian 2 datasetAbundance dataset. Samples were collected from restricted 10-20 cm shale intervals. Localities and depositional environments are indicated. Individuals were counted using the MNI protocol. The dataset was taxonomically standardized by the authors.Fl2.csvTremadocian 1 datasetAbundance dataset. Samples were collected from restricted 10-20 cm shale intervals. Localities and depositional environments are indicated. Individuals were counted using the MNI protocol. The dataset was taxonomically standardized by the authors.Tr1.csvTremadocian 2 datasetAbundance dataset. Samples were collected from restricted 10-20 cm shale intervals. Localities and depositional environments are indicated. Individuals were counted using the MNI protocol. The dataset was taxonomically standardized by the authors. Part of this dataset has been published by Balseiro et al. 2011 LethaiaTr2.csvFurongian datasetAbundance dataset. Samples were collected from restricted 10-20 cm shale intervals. Localities and depositional environments are indicated. Individuals were counted using the MNI protocol. The dataset was taxonomically standardized by the authors. Part of this dataset has been published by Balseiro et al. 2011 PalaiosFurongian.csv