DETECTIVE OF THE DEEP PAST
TROPICAL RAINFORESTS ARE AN ACCIDENT OF HISTORY The abominable mystery of flowers
To have this profile of Cretaceous pollen in the tropics could help to understand fascinating things such as the radical transformation that forests underwent with the appearance of flowers. No one has fully comprehended how it is that a forest that 145 million years ago was composed of ferns and gymnosperms, where there was not a single fruit, became the bounty of petals and pulps and sugars from the forests of 65 million years ago to the present. Darwin himself called it “the abominable mystery of flowers”. But, thanks to pollen, Jaramillo has the interesting hypothesis that while the Chixculub meteorite in Yucatan killed the dinosaurs, at the same time it created the flower empire. The impact vaporized the ground, raising an enormous wave of dust that plunged the planet into almost immediate darkness that lasted between six and nine months, followed by decades of poor, dull light. The global temperature dropped from 27 degrees Celsius before the collision to just five, and it took three decades for the climate to recover. Perhaps in this deplorable darkness, the hungry insects that once fed on the decomposed bodies of dinosaurs blindly followed the sweet scent of small flowers that were just beginning to grow, the scientist thinks. And then they pollinated them with their legs and antennae. When the light flooded the world again, the rainforest was something else. “It was a completely different world,” Jaramillo says in an article in Smithsonian magazine. “Almost all plants before the impact had become extinct after the meteorite. There were also big differences between the forests of North and South America. The latitudinal gradient (the increase in biodiversity between the tropics and the
poles) that we see today between the north and the south did not exist. It seems to be something that is related to the presence of flowering plants. “The researchers thought that the first flowers were like magnolias, but now they know that they were small, perhaps aquatic, with tiny petals, and probably scattered by insects. Perhaps angiosperms (flowering plants) ended up having an advantage over gymnosperms (without flowers) because they increasingly adapted to growing in constantly changing habitats. They became stronger, grew faster and climbed to the canopy. And once there, there would be no way for the others to compete.
A saltwater amazon
Listening to or reading Carlos Jaramillo is an endless delight. In 2017 I interviewed him for Scientific American magazine about another interesting study he conducted in the company of Uninorte geologist Jaime Escobar. The work presented evidence of how the Caribbean Sea got into what are now the eastern plains of Colombia, not just once but twice, flooding the land to the Amazon 18 and 14 million years ago, respectively. The sediment cores obtained by the two researchers contained keys such as shark teeth and piles of evidence of organisms that had to learn to live in a saline environment. The evidence forces us to consider the Amazon of those years as a lacustrine and dynamic environment, and has triggered many conjectures about its formidable biodiversity. Jaramillo has been with the Smithsonian in Panama for 13 years. He lives in one of the areas reverted by the Americans, in a house where tucans and wild turkeys arrive. His wife, María Inés Barreto, is an ornithologist graduated from the Universidad Javeriana, and helps him with the logistics of the laboratory and the mundane things of everyday life. I ask how she sees Colombia in matters of paleontology, and if, given the number of recent discoveries, she sees that the country can become a power in this discipline. He answers yes, “even though the investment is still low. That’s why Uninorte is becoming a very important university at a geological and paleontological level, because of Mapuka’s collections, because of its professors with doctorates, because of its growing level of publications, and because it is contributing to build a critical mass of professionals in paleontology. We are going to grow a lot in this decade. Sherlock Holmes himself could not have said it better.
Paleontology at school Edited by Carlos Jaramillo at the Smithsonian Tropical Research Institute, and Luz Helena Oviedo at the Humboldt Institute, and with the support of Uninorte, among other institutions, “A long time ago” is a beautifully illustrated book that traces the history of Colombian paleontology. The work is designed to take this alternative history of the national territory to schools. It included the participation of 28 specialists in the area, of which nine are from the Universidad del Norte. “There is nothing more pleasant than to see the history of Colombian life documented and illustrated as many of us have dreamed of since we were amateur fossil hunters”, Brigitte L.G. Baptiste, General Director of the Humboldt Institute.
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