How Neotropical rainforests looked 58 million years ago

Washington, October 16 (ANI): A team of scientists has used a rich cache of plant fossils discovered in Colombia to provide the first reliable evidence of how Neotropical rainforests looked 58 million years ago.

esearchers from the Smithsonian Institution and University of Florida (UF), among others, found that many of the dominant plant families existing in today's Neotropical rainforests - including legumes, palms, avocado and banana - have maintained their ecological dominance despite major changes in South America's climate and geological structure.

The study examined more than 2,000 megafossil specimens, some nearly 10 feet long, from the Cerrejón Formation in northern Colombia.

The fossils are from the Paleocene epoch, which occurred in the 5- to 7-million-year period following the massive extinction event responsible for the demise of the dinosaurs.

"Neotropical rainforests have an almost nonexistent fossil record," said study co-author Fabiany Herrera, a graduate student at the Florida Museum of Natural History on the UF campus.

"These specimens allow us to actually test hypotheses about their origins for the first time ever," he added.

The new study provides evidence Neotropical rainforests were warmer and wetter in the late Paleocene than today but were composed of the same plant families that now thrive in rainforests.

"We have the fossils to prove this. It is also intriguing that while the Cerrejon rainforest shows many of the characteristics of modern equivalents, plant diversity is lower," Herrera said.

"These new plant fossils show us that the forest during the time of Titanoboa, 58 million years ago, was similar in many ways to that of today," said Florida Museum vertebrate paleontologist Jonathan Bloch.

"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," he added.

Researchers were surprised by the relative lack of diversity found in the Paleocene rainforest.

Statistical analyses showed that the plant communities found in the Cerrejon Formation were 60 percent to 80 percent less diverse than those of modern Neotropical rainforests.

Evidence of herbivory also showed a low diversity level among insects.

According to researchers, the relative lack of diversity indicates either the beginning of rainforest species diversification or the recovery of existing species from the Cretaceous extinction event.

The researchers estimate the Paleocene rainforest received about 126 inches of rainfall annually and had an average annual temperature greater than 86 degrees.

The Titanoboa study, which used different methods, estimated an average temperature between 89 and 91 degrees. Today, the region's temperatures average about 81 degrees. (ANI)