Reconstructing Cenozoic Patagonian biotas using multi-proxy fossil records

PALAZZESI, L,; VIZCAINO, S.; BARREDA, V.; CUITIÑO, JOSÉ I.; DEL RÍO, C. J.; GOIN, F.; GONZALEZ ESTEBENET, M.; GULER, M.V.; GANDOLFO, M.A.; KAY, R.; PARRAS, A.; REGUERO, M.; ZAMALOA, M.C.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2021

0895-9811

The fossil record from Cenozoic sediments provides a great deal of information that has direct bearing on theearly assembling of modern Patagonian ecosystems. In this synthesis, we revise selected fossil marine andterrestrial records from the last 66 Ma with the aim of understanding major shifts of Patagonian biotas. From thePaleocene to the mid Eocene this region supported outstandingly diverse terrestrial assemblages that show strongconnections to modern-day Australasia (e.g. gum trees, casuarinas, monotremes). Nearshore marine biotasconfirm peak warmth conditions, with tropical species with Tethyan affinities. The late Eocene and earlyOligocene marks the onset of a period of overall regional cooling, drying, and increasingly variable ecologicalconditions. The rise of palm-dominated flammable biomes in hinterlands and the prevalence of Gondwanangallery forest (e.g. southern beeches and podocarps) along river-sides supported the existence of mosaic habitatsmaintained by edaphic and regional climatic conditions. This shift in landscapes reflects the evolution of a widerange of herbivorous mammals (e.g. Notoungulata, Litopterna, and Astrapotheria). The late Oligocene and earlyto-mid Miocene witnessed a dramatic modification of landscapes including the incursion of high sea-level episodes,the emergence of specialized coastal (i.e. salt-marsh) plant taxa and the expansion of large herbivorousmammals with predominantly high-crowned teeth (e.g. Notoungulata: Hegetotheriidae, Interatheriidae, andMesotheriidae). The cooling trend of this interval was interrupted by a mid-Miocene transient warming event,with the dispersion of terrestrial (e.g. platyrrhine monkeys, palms) and marine (e.g. Tuberculodinium vancampoae)elements with tropical affinity into southernmost South American regions. Seasonally-dry conditions increasedtowards the end of the Miocene, yet subtropical species persisted either in terrestrial (e.g. malpighs, passionvines, capybaras), and marine (e.g. Subtropical and Caribbean molluscs) environments. The increasing ariditycaused by the Andean uplift wiped out most of the forest species and promoted the diversification of open-habitatspecies; the emergence of the current grass-dominated Patagonian Steppe occurred later on, probably during theQuaternary.