Abstract Detail

Paleobotanical Section

Donovan, Michael [1], Iglesias, Ari [2], Wilf, Peter [3], Cuneo, N. Ruben [4], Labandeira, Conrad [5].

Rapid recovery of plant-insect associations in Patagonia after the Cretaceous-Paleogene mass extinction.

Study of the end-Cretaceous mass extinction has been heavily regionally biased towards the western USA. Recently, a growing body of evidence, especially from Patagonia, Argentina, suggests that extinction and recovery dynamics may have been very different in Gondwana. Low pollen extinction across the Cretaceous–Paleogene (K-Pg) boundary, the survival of many vertebrate and typically mid-Mesozoic gymnosperm lineages into the Paleocene, and the discovery of diverse early Paleocene macrofloras have led to the hypothesis that Patagonia provided a refugium for biodiversity during the global catastrophe. Plants and associated insect herbivores provide the foundation for most terrestrial food webs. To test whether Patagonia provided a refuge for associational diversity, we compared insect damage on latest Cretaceous and early Paleocene fossil floras from coastal deposits in Chubut Province, Patagonia to previously studied insect damage from the western USA, which decreased significantly at the K-Pg boundary. We compared ca. 850 leaf fossils from the latest Maastrichtian (67–66 Ma) Lefipán Formation in northwestern Chubut to ca. 2750 fossil leaves from three Danian time intervals, including localities that correlate to paleomagnetic chrons C29n and C28n in the Salamanca Formation and C27n in the overlying Peñas Coloradas Formation. We found that insect damage types (DTs) on both the Cretaceous and Paleocene floras (50 Cretaceous and 61 Paleocene DTs) are more diverse than in the western USA (49 Cretaceous and 44 early Paleocene DTs from much larger sample sizes). Also, comparisons of sampling-standardized DT diversity in Patagonia revealed a lower K-Pg decrease than what has previously been observed in North America during the same interval. In addition, damage diversity, including overall and specialized DT diversity, increased through the three early Paleocene time intervals. We also analyzed the morphology of Patagonian leaf mines to determine if any leaf miners crossed the K-Pg boundary. Our preliminary results do not suggest any clear boundary-crossing leaf mines, even on surviving plant species, similar to the pattern observed in the western USA. Instead, there are many new leaf mine associations that first appear at the early Paleocene localities, providing further evidence for a faster recovery of insect herbivore diversity in Patagonia compared to the western USA. These results, combined with earlier work, support an emerging hypothesis that southern latitudes suffered significant extinctions, but recovered much more quickly from the global environmental disaster after the end-Cretaceous impact.

1 - Pennsylvania State University, Geosciences, 236 Deike Building, University Park, PA, 16802, USA
2 - Universidad Nacional del COMAHUE, Instituto de Investigaciones en Biodiversidad y Medioambiente INIBIOMA-CONICET, Quintral 1250, San Carlos de Bariloche, Río Negro, 8400, Argentina
3 - Penn State Univ., 537 Deike Bldg., University Park, PA, 16802, USA
4 - Mef Av. Fontana 140, Trelew-Chubut, N/A, 9100, Argentina
5 - National Museum of Natural History, Smithsonian Institution, Department of Paleobiology, 10th St. & Constitution Ave. NW, Washington, D.C., 20013, USA

Keywords:
plant-insect interactions
paleobotany
Cretaceous-Paleogene extinction
herbivory
Patagonia.

Presentation Type: Oral Paper:Papers for Sections
Session: 11
Location: Salon 5/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 11:45 AM
Number: 11007
Abstract ID:946
Candidate for Awards:Isabel Cookson Award