Fósseis do Paleoceno Inferior da Formação Cerrejón, Colombia: o registro mais antigo de floresta neotropical

Late Paleocene fossils from the Cerrejón Formation, Colombia, are the earliest record of Neotropical rainforest

Scott L. Wing a,1, Fabiany Herrera b,c, Carlos A. Jaramillo b, Carolina Gómez-Navarro b,d, Peter Wilf e and Conrad C. Labandeira a

+ Author Affiliations

aDepartment of Paleobiology, P.O. Box 37012, Smithsonian Institution, National Museum of Natural History, Washington, DC 20013;

bSmithsonian Tropical Research Institute, Apartado Postal 0843-03092, Balboa, Ancon, Panamá, República de Panamá;

cFlorida Museum of Natural History and Department of Biology, University of Florida, P.O. Box 117800, Gainesville, FL 32611-7800;

dDepartment of Plant and Microbial Biology, University of California, Berkeley, CA 94720; and

eDepartment of Geosciences, Pennsylvania State University, University Park, PA 16802

Edited by Peter H. Raven, Missouri Botanical Garden, St. Louis, MO, and approved September 4, 2009 (received for review May 11, 2009)

Abstract

Neotropical rainforests have a very poor fossil record, making hypotheses concerning their origins difficult to evaluate. Nevertheless, some of their most important characteristics can be preserved in the fossil record: high plant diversity, dominance by a distinctive combination of angiosperm families, a preponderance of plant species with large, smooth-margined leaves, and evidence for a high diversity of herbivorous insects. Here, we report on an ≈58-my-old flora from the Cerrejón Formation of Colombia (paleolatitude ≈5 °N) that is the earliest megafossil record of Neotropical rainforest. The flora has abundant, diverse palms and legumes and similar family composition to extant Neotropical rainforest. Three-quarters of the leaf types are large and entire-margined, indicating rainfall >2,500 mm/year and mean annual temperature >25 °C. Despite modern family composition and tropical paleoclimate, the diversity of fossil pollen and leaf samples is 60–80% that of comparable samples from extant and Quaternary Neotropical rainforest from similar climates. Insect feeding damage on Cerrejón fossil leaves, representing primary consumers, is abundant, but also of low diversity, and overwhelmingly made by generalist feeders rather than specialized herbivores. Cerrejón megafossils provide strong evidence that the same Neotropical rainforest families have characterized the biome since the Paleocene, maintaining their importance through climatic phases warmer and cooler than present. The low diversity of both plants and herbivorous insects in this Paleocene Neotropical rainforest may reflect an early stage in the diversification of the lineages that inhabit this biome, and/or a long recovery period from the terminal Cretaceous extinction.


diversity stability paleoclimate paleobotany Fabaceae

Footnotes

1To whom correspondence should be addressed. E-mail: wings@si.edu

Author contributions: S.L.W., F.H., and C.A.J. designed research; S.L.W., F.H., C.A.J., C.G.-N., P.W., and C.C.L. performed research; S.L.W., C.A.J., P.W., and C.C.L. analyzed data; and S.L.W., F.H., C.A.J., and P.W. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

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NOTA IMPERTINENTE DESTE BLOGGER:

58 milhões de anos e a seleção natural não fez nada? 2.000 exemplares de megafósseis, de um período de 5 a 8 milhões de anos após a extinção dos dinossauros, e a única diferença entre a floresta antiga e a moderna é que a última tem mais diversidade?

E o que dizer então da toda-poderosa e onipresente seleção natural: não fez nada em um grande nicho ecológico durante 58 milhões de anos?

A evolução da baleia ocorreu em menos tempo do que isso, não é mesmo? É, a evolução tem coisas sobre a seleção natural que a própria razão desconhece...