Evidence Is Weak for Tropical Rainforest 65 Million Years Ago in Africa's Low Latitudes, Paleobotanist Says
ScienceDaily (Oct. 24, 2010) — The landscape of Central Africa 65 million years ago was a low-elevation tropical belt, but the jury is still out on whether the region's mammals browsed and hunted beneath the canopy of a lush rainforest.
This is an ancient leaf fossil discovered in Africa by a team of scientists that included paleobotanist Bonnie Jacobs from SMU in Dallas. (Credit: Jacobs, SMU)
The scientific evidence for a tropical rainforest at that time is weak and far from convincing, says paleobotanist Bonnie F. Jacobs at Southern Methodist University in Dallas.
Fossil pollen from Central and West Africa provide no definitive evidence for communities of rainforest trees at the beginning of the Cenozoic, says Jacobs, an expert in the paleobotany of Africa soon after dinosaurs had gone extinct. It was the start of the age of mammals, and Africa was largely an island continent.
Many Cenozoic mysteries remain to be solved
The rainforest mystery is characteristic of the scientific uncertainty and unknowns surrounding Africa's ancient flora during the period called the Cenozoic. There are large gaps in the fossil record, says Jacobs, a co-author of "A Review of the Cenozoic Vegetation History of Africa." She is an associate professor in SMU's Roy M. Huffington Department of Earth Sciences.
The review, a chapter in "Cenozoic Mammals of Africa" (University of California Press, 2010), is the first of its kind since 1978 to review and interpret the Cenozoic paleobotanical record of Africa with paleogeographic maps showing paleobotanical site distributions through time. Jacobs co-authored the paper with Aaron D. Pan, a paleobotanist at the Fort Worth Museum of Science and History, and Christopher R. Scotese, in the Earth Sciences Department at the University of Texas at Arlington.
The 1008-page "Cenozoic Mammals of Africa" is the first comprehensive scientific reference of its kind since 1978, comprising 48 chapters by 64 experts. The volume summarizes and interprets the published fossil research to date of Africa's mammals, tectonics, geography, climate and flora of the past 65 million years.
Details sparse, but big picture emerges for past 65 million years
Paleobotanical data for Africa are generally meager and uneven for the Cenozoic, according to Jacobs and her co-authors.
In an original series of maps, they chart each Cenozoic Africa paleobotanical locale described in the published research to date. There are a mere 82 sites in all. Most of the sites date to 50 million years ago. Fewer date to 20 million, 30 million, 10 million and -- perhaps most important -- 2 million years ago, when the human family was evolving.
"Africa is disappointingly undersampled," say Jacobs and her colleagues. "This vast continent, roughly three times the area of the United States, has so far been documented by only a handful of Paleogene plant and vertebrate localities, and it has a Neogene record heavily biased toward the depositional basins of the East African Rift."
...
Read more here/Leia mais aqui: Science Daily
