INIBIOMA   20415
INSTITUTO DE INVESTIGACIONES EN BIODIVERSIDAD Y MEDIOAMBIENTE
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
First comparison of latest Cretaceous and Early Paleocene insect damage in the Southern Hemisphere supports a Patagonian biodiversity refugium
Autor/es:
DONOVAN MICHAEL; IGLESIAS ARI; WILF, P. D.; CÚNEO RUBEN; LABANDEIRA CONRAD
Lugar:
Mendoza
Reunión:
Congreso; 4th International Paleontological Congress; 2014
Institución organizadora:
CONICET-MENDOZA
Resumen:
Most research on terrestrial ecosystems after the Cretaceous-Paleogene (K-Pg) asteroid impact comes from a relatively small area of the western USA, severely limiting our understanding of global extinction and recovery patterns. In that region, plants and associated insect-damage diversity decreased significantly at the K-Pg boundary, and specialized damage types (DTs) were disproportionately affected in the extinction. Here, we present results comparing insect damage on latest Cretaceous and early Paleocene fossil floras from coastal deposits in Chubut Province, Patagonia, Argentina, comprising the first study of its kind done outside the western USA. We compared ca. 850 leaf fossils from the latest Maastrichtian (67-66 Ma) part of the Lefipán Formation in northwestern Chubut to approximately 2000 leaf fossils from the early Danian Salamanca Formation, located ca. 360 km to the southeast (~50° south paleolatitude). Insect damage to both the Cretaceousand Paleocene floras (56 DTs each) is more diverse than in the western USA (49 Cretaceous and 44 Paleocene DTs from a much larger sample size) and includes many new associations. Examples of new DTs from the Lefipán Formation are spheroidal galls on primary veins surrounded by a wide rim of thickened woody tissue, and ellipsoidal to spheroidal galls composed of carbonized material with striated surfaces. The Paleocene Salamanca floras are also associated with high DT diversity, including 12 specialized DTs not found at the Lefipán localities, suggesting a more rapid recovery of insect herbivory in Patagonia compared to the western USA. Examples of new, Paleocen especialized DTs include concentric rings of piercing and sucking marks, mines, and galls on the oldest known Agathis. Comparisons of sampling-standardized DT diversity from the Cretaceousto Paleocene revealed a lower decrease than what has previously been observed in North America during the same interval.These results, combined with earlier work demonstrating minimal overall pollen extinction across the K‒Pg boundary in the Lefipán Formation, support an emerging hypothesis that southern latitudes were buffered from the global environmental disaster after the end-Cretaceous impact. This buffering provided a refugium for associational diversity, as well as the survival of a long list of nominally Mesozoic plant and vertebrate clades.