Ben Creisler
New non-dino papers:
MÃnica R. Carvalho, Carlos Jaramillo, Felipe de la Parra, Dayenari Caballero-RodrÃguez, Fabiany Herrera, Scott Wing, Benjamin L. Turner, Carlos DâApolito, Millerlandy Romero-BÃez, Paula NarvÃez, Camila MartÃnez, Mauricio Gutierrez, Conrad Labandeira, German Bayona, Milton Rueda, Manuel Paez-Reyes, Dairon CÃrdenas, Ãlvaro Duque, James L. Crowley, Carlos Santos & Daniele Silvestro (2021)
Extinction at the end-Cretaceous and the origin of modern Neotropical rainforests.
Science 372(6537): 63-68
DOI: 10.1126/science.abf1969
https://science.sciencemag.org/content/372/6537/63The birth of modern rainforests
The origin of modern rainforests can be traced to the aftermath of the bolide impact at the end of the Cretaceous. Carvalho et al. used fossilized pollen and leaves to characterize the changes that took place in northern South American forests at this time (see the Perspective by Jacobs and Currano). They not only found changes in species composition but were also able to infer changes in forest structure. Extinctions were widespread, especially among gymnosperms. Angiosperm taxa came to dominate the forests over the 6 million years of recovery, when the flora began to resemble that of modern lowland neotropical forest. The leaf data also imply that the forest canopy evolved from relatively open to closed and layered, leading to increased vertical stratification and a greater diversity of plant growth forms.
Abstract
The end-Cretaceous event was catastrophic for terrestrial communities worldwide, yet its long-lasting effect on tropical forests remains largely unknown. We quantified plant extinction and ecological change in tropical forests resulting from the end-Cretaceous event using fossil pollen (>50,000 occurrences) and leaves (>6000 specimens) from localities in Colombia. Late Cretaceous (Maastrichtian) rainforests were characterized by an open canopy and diverse plantâinsect interactions. Plant diversity declined by 45% at the CretaceousâPaleogene boundary and did not recover for ~6 million years. Paleocene forests resembled modern Neotropical rainforests, with a closed canopy and multistratal structure dominated by angiosperms. The end-Cretaceous event triggered a long interval of low plant diversity in the Neotropics and the evolutionary assembly of todayâs most diverse terrestrial ecosystem.
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Summary
About 66 million years ago (Ma), at the boundary of the Cretaceous-Paleogene (K/Pg) period, a sudden mass extinction was triggered by the impact of a bolide, destroying an estimated three-quarters of Earth's plant and animal species. The long-term effects of this event varied across Earth, and little is known about the outcome in low-latitude regions of the world. On page 63 of this issue, Carvalho et al. (1) report analyses of fossil pollen and leaf data across the K/Pg boundary, ~1500 km south of the Chicxulub crater left behind by the impact. They assessed plant diversity and structure in the lowland tropics before and after the catastrophe, put their interpretations into the broader context of flowering plant (angiosperm) evolution, and answer one of the biggest questions in paleobotany: When and how did the diverse, angiosperm-dominated, stratified tropical forests of South America emerge?
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