DOI: 10.5061/dryad.h9w0vt4dz
title: The environmental factors limiting the distribution of shallow-water terebratulid brachiopods

description: The Cenozoic genus Terebratula seems to be an exception to the
 Post-Permian trend in brachiopod retreat to offshore habitats because it
 was species-rich and numerically abundant in warm-temperate shallow-water
 environments in the Mediterranean and the Paratethys realms. This was so
 despite the general dominance of bivalves and the pervasive bioturbation
 and predation pressure during the Neogene. Terebratula, however, went
 extinct in the Calabrian (Pleistocene). The optimal environmental
 conditions for Terebratula during its prime are poorly known. The Águilas
 Basin (SE Spain) is an ideal study area to investigate the habitat of
 Terebratula because shell beds of this brachiopod occur there cyclically
 in early Pliocene deposits. We evaluate the paleoecological boundary
 conditions controlling the distribution of Terebratula by estimating its
 environmental tolerances using benthic and planktic foraminiferal and
 nannoplankton assemblages and oxygen isotopes of the secondary layer
 brachiopod calcite. Our results suggest that Terebratula in the Águilas
 Basin favored oligotrophic to mesotrophic, well-oxygenated environments at
 water depths of 60-90 m. Planktic foraminiferal assemblages and oxygen
 isotopes point to sea-surface temperatures between ~16 and 22ºC, and
 bottom-water temperatures between 17 and 24ºC. The analyzed proxies
 indicate that Terebratula tolerated local variations in water depth,
 bottom temperature, oxygenation, productivity and organic enrichment.
 Terebratula was probably excluded by grazing pressure from well-lit
 environments and preferentially occupied sediment-starved, current-swept
 upper offshore habitats where coralline red algae were absent. Narrow
 temperature ranges of Terebratula species might have been a disadvantage
 during the high-amplitude seawater temperature fluctuations that started
 about 1 Myr ago, when the genus went extinct.
description: The samples were collected from the Cabezo Alto section and
 additional Terebratula outcrops from the same stratigraphic sequence
 (early Pliocene, Águilas Basin, SE Spain).
description: SUPPLEMENTARY FIGURE 1. Two-way (Q-mode, R-mode) Paired Group Average (UPGMA) cluster analysis. The samples associated with <i>Terebratula</i> are indicated by thick white vertical lines. SUPPLEMENTARY FIGURE 2. Distribution of the main planktonic foraminifera (first two rows) and calcareous nannoplankton (last row) taxa in the Cabezo Alto section. The red and blue bands represent warm and cold periods identified with transfer functions of planktonic foraminifera. <i>Globigerinoides</i> gr. <i>ruber</i> includes <i>G. ruber</i>, <i>G. obliquus</i> and <i>G. extremus</i>. SUPPLEMENTARY TABLE 1. Habitats of some extant Terebratulida bathymetrically equivalent to <i>Terebratula</i>. Datasets include: depth ranges and abundance of benthic foraminifera, relative abundance of ecological groups of benthic foraminifera from the rarefied dataset (rarefied to 200 specimens per sample), relative abundance of aggregated species of planktonic foraminifera categorized as cold-eutrophic and warm-oligotrophic and abundance of calcareous nannoplankton.