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; ARI IGLESIAS; WILF PETER; CÚNEO RUBEN; LABANDEIRA CONRAD
Lugar:
Colorado
Reunión:
Congreso; Geological Sociaty of America Annual Meeting; 2013
Institución organizadora:
Geological Sociaty of America
Resumen:
In the western
USA, insect feeding-damage diversity on fossil leaves decreased significantly
across the Cretaceous-Paleogene (K‒Pg)
boundary as a result of the Chicxulub impact. However, little is known about
plant-insect associations across this interval in the Southern Hemisphere. We
present preliminary results comparing insect damage on latest Cretaceous with
early Paleocene fossil floras from coastal deposits in Chubut Province,
Patagonia, Argentina, the first such study done outside the western USA. We
compared ca. 1000 leaf fossils from two sites in the late Maastrichtian Lefipán
Formation in northwestern Chubut to approximately 2000 leaf fossils from two
sites in the Danian Salamanca Formation, located ca. 360 km to the southeast
(~50° south paleolatitude).
Insect damage on both the Cretaceous and Paleocene
floras appears more diverse than North American analogs and includes many new
associations. Examples of new fossil damage types 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. Most
early Paleocene plant localities from the western USA are associated with low
plant and damage type diversity and a homogenous, generalized composition
across sites. In contrast, the Paleocene Salamanca floras are associated with
high damage type diversity and a number of new damage types. Examples include
concentric rings of piercing and sucking marks, small holes surrounded by dark,
blotched reaction tissue, and mines and two gall types on the oldest known Agathis. These preliminary results
suggest that extinction of insect herbivores at the K‒Pg
boundary was less severe or recovery was more rapid in southern South America compared to previously studied North American analogs.
High early Paleocene damage diversity, combined with earlier work demonstrating
minimal overall pollen extinction across the K‒Pg
boundary in the Lefipán Formation, supports
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.