The birth of the modern rainforest
The origin of the modern rainforest can be traced back to the consequences of the boride impact at the end of the Cretaceous.Carvalho Wait. Fossil pollen and leaves are used to characterize the changes that occurred in the forests of northern South America at this time (see Jacobs and Currano’s “View”). They not only found changes in species composition, but were also able to infer changes in forest structure. Extinctions are common, especially in gymnosperms. After 6 million years of restoration, the angiosperm flora gradually became the dominator of the forest. At that time, the flora began to resemble modern lowland neotropical forests. The leaf data also implied that the forest canopy changed from relatively open to closed and stratified, leading to increased vertical stratification and diversity of plant growth forms.
science, This question p. 63; see also age 28
The end-Cretaceous events were disastrous for terrestrial communities around the world, but their lasting effects on tropical forests remain largely unknown. We used fossil pollen (>50,000 times) and leaves (>6000 samples) from the Columbia area to quantify the extinction and ecological changes of tropical forests caused by the end-Cretaceous events. The late Cretaceous (Maastrichtian) rainforest was characterized by an open canopy and a variety of plant-insect interactions. In the Cretaceous-Palaeozoic world, plant diversity declined by 45% and did not recover in approximately 6 million years. Paleocene forests are similar to modern neotropical rain forests, with closed canopies and multi-layered structures dominated by angiosperms. The end-Cretaceous events triggered long periods of low plant diversity in the neotropical region and triggered the evolution of today̵