Paleoenvironmental and Biotic Changes in the Late Triassic of Argentina: Testing Hypotheses of Abiotic Forcing at the Basin Scale

MANCUSO, ADRIANA CECILIA; IRMIS, RANDALL; PEDERNERA, TOMÁS; GAETANO, LEANDRO; BENAVENTE, CECILIA ANDREA; BREEDEN, BENJAMIN

Frontiers in Earth Science

Springer

Año: 2022

2296-6463

Paleoenvironmental factors such as climate change are often hypothesized as critical forecosystem changes over evolutionary time scales. Theoretically, these changes should beobservable in the fossil record, but the robust linkage of biotic shifts to climate eventsremains difficult. The Late Triassic Period is an ideal interval for testing such hypotheseswithin terrestrial ecosystems because of a number of large-scale climate events, such asthe Carnian Pluvial Episode (CPE), and a rich, well-studied fossil record. Nonetheless, atregional to global scales, few linkages have been identified during most of the Late Triassic.Here, we synthesize a multi-proxy basin-scale dataset of paleoenvironmental data,including new information from clay mineralogy and paleosol major- and trace-elementgeochemistry, to understand paleoclimate changes in the Ischigualasto-Villa Unión Basinof northwestern Argentina. In combination with diversity and relative abundanceinformation from the well-sampled plant and tetrapod fossil record in the basin, wethen use accepted evolutionary models of abiotic forcing of changes in ecosystems totest previously proposed hypotheses of floral and faunal variations at a basin scale. We findthat although many patterns are best explained by sampling issues and taphonomy,pseudosuchian archosaur diversity and rhynchosaur relative abundance conform topredictions of paleoenvironmental forcing as the climate changed from warmer, drierconditions to more temperate humid conditions. These data demonstrate how highresolution multi-proxy data and a well-sampled fossil record at a basin-scale can be usedto test hypotheses of abiotic forcing of ecosystems in deep time, and highlights wherefuture efforts should be directed in terms of filling data gaps and testing new hypotheses.