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Biogeochemical (δ13C, δ15N, and δ18O values) and ecomorphological analyses of the early Pleistocene fauna of Venta Micena (Orce, Guadix-Baza basin, SE Spain) provide interesting clues on the physiology, dietary regimes, habitat preferences, and ecological interactions of large mammals. Such inferences are useful in deciphering aspects of paleocommunity structure and predator-prey relationships. Specifically, the hypsodonty index combined with δ13C values allows classifying the ungulates among grazers from open habitat (Equus altidens, Bison sp., Praeovibos sp., Hemitragus albus, Hippopotamus antiquus, and Mammuthus meridionalis), mixed feeders (Soergelia minor and Pseudodama sp.), and browsers from canopy areas (Stephanorhinus sp. and Praemegaceros cf. verticornis). Given that δ13C values indicate that all these herbivores fed exclusively on C3 plants, significant differences in isotopic values between perissodactyls (monogastric, hindgut fermenters) and ruminants (foregut fermenters) reflect differences in digestive efficiency. Values of δ18O indicate the dietary water source of ungulates, revealing that Pseudodama sp., Hemitragus albus, and Soergelia minor obtained a significant fraction of their metabolic water from vegetation. Carnivores show higher δ15N values than herbivores, which records the isotopic enrichment expected with an increase in trophic level. Hippopotamus antiquus and Praeovibos sp. have unexpectedly high δ15N values, suggesting that they predominantly consumed aquatic plants and lichens, respectively. Inferences on predator-prey relationships, derived from the use of linear mixing models, indicate resource partitioning among sympatric predators; saber-tooth Megantereon whitei and jaguar Panthera cf. gombaszoegensis were ambushers in closed habitat while saber-tooth Homotherium latidens and wild dog Lycaon lycaonoides were coursing predators in open plains. The giant hyena Pachycrocuta brevirostris scavenged the prey of these hypercarnivores.
Climate change has exerted a major influence on the biosphere in historical times, altering the geographic range of many species and elevating the extinction risk in both marine and terrestrial realms. This study investigates marine community change during the major early Permian climatic transition from the late Paleozoic ice age to a largely ice-free greenhouse climate. Quantitative counts of fossil abundance from 71 field assemblages and 15 collections from the literature, spanning the early and middle Permian (Sakmarian– Capitanian) of the Tasmania, Sydney, and Bowen basins of eastern Australia document substantial changes in the composition of marine communities during Sakmarian–Kungurian postglacial warming. During the last stages of glaciation (Sakmarian), communities were dominated by the brachiopod Trigonotreta and the bivalve Eurydesma, whereas communities from the later greenhouse climate (Kungurian–Guadalupian) contained abundant productide brachiopods such as Terrakea and Echinalosia. The shift was broadly synchronous at all paleolatitudes within eastern Australia but appears to have occurred first in offshore habitats. Artinskian communities may also have been much more variable than either earlier or later communities. This variability may have been triggered by rapid climate fluctuations, similar to the changes observed in Artinskian tropical terrestrial ecosystems, but it may also stem from sampling a greater number of depositional environments and habitat types. The ultimate fate of the dominant glacial genera differed after they lost dominance, with Eurydesma becoming extinct during climate warming but Trigonotreta persisting at low abundance levels for a much longer time. These results support the theory that climate change most often causes extinctions through indirect paleoecological effects and underscore the important consequences that even gradual, long-term climate change can have in marine ecosystems.
An isolated limestone deposit preserving thousands of specimens of the dimerelloid brachiopod Peregrinella multicarinata is exposed in fossil-poor Hauterivian strata northwest of the town of Planerskoje on the Crimean Peninsula in southern Ukraine. The limestone consists of micrite that encloses abundant detrital components, mostly brachiopod shell fragments, and also contains authigenic, framboidal pyrite. Cavities are rare; a few have been filled by a sequence of anhedral yellow calcite, seam micrite, banded and botryoidal cement, and equant calcite spar. The limestone preserves a diverse mollusk fauna of low abundance, including modiomorphid, lucinid, and buchiid bivalves and abyssochrysoid, ampullinid, and neritid gastropods. The negative δ13C values of the micrite (as low as −13.6‰) and the character of the associated mollusk fauna indicate that this limestone formed at an ancient hydrocarbon seep. This evidence supports the earlier interpretation of Peregrinella as a seep-restricted brachiopod. The new Ukrainian records of some of the mollusk taxa—notably Caspiconcha and Paskentana—significantly extend the geographic range of these apparently seep-restricted mollusks, suggesting that mollusks at Early Cretaceous seeps had a wider geographical distribution than previously appreciated.
Linking biotic patterns across spatiotemporal scales provides a greater understanding of the processes that drive ecological and evolutionary change. Here, we examine how global patterns of biotic turnover are expressed in the structure of regional biotic gradients from the Illinois Basin (USA) during the late Paleozoic ice age (LPIA)— an interval noted for low global rates of taxonomic turnover. Results indicate that the pre-LPIA interval is characterized by well-defined biotic gradients; depositional environments are dominated by distinct sets of taxa, arrayed along a gradient of substrate composition, and are clearly differentiated by ordination and ANOSIM analyses. There is a marked shift in gradient structure across the onset of the LPIA; environments become weakly distinguished, are dominated by similar sets of taxa that are widespread across the ramp, and are arrayed along a nearshore-offshore gradient. Our results are consistent with findings from global-level studies, which indicate that broadly adapted taxa (eurytopes) increased in importance following the start of the LPIA. Unlike the global level, however, the regional increase in eurytopy is not linked to the extinction of narrowly adapted taxa in response to climate change. Instead, eurytopy increased as the geometry of the Illinois Basin shifted from a flat carbonate ramp, composed of shallower-water and higher-stress environments in the pre-LPIA interval, to a steeper ramp comprising deeper-water and more stable habitats in the LPIA interval. We suggest that increased eurytopy drove (1) a previously documented decrease in regional-level turnover during the late Paleozoic and (2) a perceived pattern of greater persistence in late versus early Paleozoic biotic gradients.
Purple to violet colored millericrinids (Crinoidea) are described from the lower Kimmeridgian of the Małogoszcz quarry, Holy Cross Mountains, Poland. By chemical analysis using high-performance liquid chromatography, ultraviolet/visible spectroscopy, and mass spectrometry, the organic compounds were characterized as a homologous series of hypericinoid pigments ranging from C28H12O8 (fringelite F) to C36H28O8. The results indicate that hypericinoid pigments were more widespread in millericrinids than previously known. The presence of new hypericin derivatives in the fossil crinoids with characteristic alkyl side chains shows that Mesozoic hypericinoid pigments were closely related to recent crinoidal pigments.