Present day tropical plant families survived in warmer, wetter tropics 58 million years ago
Jeremy Hancemongabay.com
October 18, 2009
Despite large changes in the climate and geology since—including a cooling in the tropics—scientists found that many flora species dominating the landscape 58 million years ago, known as the Paleocene, still dominate today, including legumes, palms, avocado, and banana. Their discoveries could have important implications for researchers working to predict how the tropics will react to climate change. Many biologists have feared that a warmer earth will devastate rainforests assuming the flora will simply be unable to withstand hotter temperatures. This study may bring everyone back to the drawing board.
 Leaf in the tropical rainforests of Colombia. Photo by: Rhett A. Butler. |
The fact that the scientists were able to examine fossils made a big difference. Researchers have had to depend on pollen analysis for information about past tropical forests, but pollen only allows identification of species to the family level, while the fossils revealed lineage all the way down to the plant's genus by examining the structure of preserved leafs. Moreover, fossils provide important information about insect types, climate, and forest structure.
Studying the many and varied fossils, researchers found that the Paleocene in Colombia was warmer and wetter than today with an estimated annual temperature of 86 degrees Fahrenheit and 126 inches of rainfall, whereas the average temperature of today's Colombian rainforest is 81 degrees Fahrenheit.
"It is also intriguing that while the Cerrejón rainforest shows many of the characteristics of modern equivalents, plant diversity is lower," Herrera said. Statistical analysis found that the diversity in the ancient tropical forests was 60 to 80 percent less than diversity today. Two different hypotheses have been put forward to explain this: one is that the period represents the epoch in which tropical forest diversification was just beginning; the other is that the forest ecosystem was in the midst of species-recovery after the extinction event that wiped out the dinosaurs and many others.
 A boa constrictor in Colombia--an ancestor of Titanoboa. Photo by: Rhett A. Butler. |
"Like Titanoboa, which is clearly related to living boas and anacondas, the ancient forest of northern Colombia had similar families of plants as we see today in that ecosystem. The foundations of the Neotropical rainforests were there 58 million years ago," said Florida Museum vertebrate paleontologist Jonathan Bloch, who described Titanoboa but was not part of the rainforest study.
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