THE AGE AND DIVERSIFICATION OF TERRESTRIAL NEW WORLD ECOSYSTEMS THROUGH CRETACEOUS AND CENOZOIC TIME
THE AGE AND DIVERSIFICATION OF TERRESTRIAL NEW WORLD ECOSYSTEMS THROUGH CRETACEOUS AND CENOZOIC TIME
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DOI：
10.3732/ajb.1000353
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发表时间：
2011-03-01
影响因子：
3
通讯作者：
Graham, Alan
中科院分区：
文献类型：
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作者：
Graham, Alan
在大约1亿年前的白垩纪，新世界出现了8个生态系统，最终发展成为现代地球公认的12个生态系统。在这段时间内，推动生物变化的强迫机制包括白垩纪末期全球气温的下降，65 Ma的小行星撞击和大陆边缘和内部的海洋排水加剧了全球气温的下降；南美洲与非洲的分离始于大约120 Ma的南部，并向北推进，直到完成90-100 Ma；挪威海的火山喷发可能会释放出1500亿吨甲烷和二氧化碳，导致本已温暖的地球温度上升5至6摄氏度；大约45 Ma时北大西洋陆桥断裂，当时气温正在下降；安第斯山脉的上升开始于大约40 Ma；约32 Ma，南美洲和南极洲之间的德雷克海峡开通，约30 Ma，洪堡寒流形成；北美洲和南美洲的联合约3.5 Ma；所有这些都在进化过程的覆盖范围内。这些过程产生了一系列元素（例如，在整体干燥环境中生长在潮湿栖息地的物种；廊林），早期版本（例如，直到始新世中期没有根藻的红树林群落），以及当今新世界生态系统的基本现代版本。初步估计，化石记录表明，早期的水生群落（包括一个突出的被子植物成分）出现在中白垩世至晚白垩世早期，低地新热带雨林出现在64 Ma （58-55 Ma发育良好），灌木/灌木林-林地-稀树草原和草原出现在中新世中期气候最佳时期约15-13 Ma，沙漠出现在中新世中期/上新世早期约10 Ma，重要的冻原出现在约7-5 Ma。以及此后不久的高山苔原（paramo），由于海拔较高，温度升高，例如在安第斯山脉
Eight ecosystems that were present in the Cretaceous about 100 Ma (million years ago) in the New World eventually developed into the 12 recognized for the modern Earth. Among the forcing mechanisms that drove biotic change during this interval was a decline in global temperatures toward the end of the Cretaceous, augmented by the asteroid impact at 65 Ma and drainage of seas from continental margins and interiors; separation of South America from Africa beginning in the south at ca. 120 Ma and progressing northward until completed 90-100 Ma; the possible emission of 1500 gigatons of methane and CO2 attributed to explosive vents in the Norwegian Sea at ca. 55 Ma, resulting in a temperature rise of 5 degrees-6 degrees C in an already warm world; disruption of the North Atlantic land bridge at ca. 45 Ma at a time when temperatures were falling; rise of the Andes Mountains beginning at ca. 40 Ma; opening of the Drake Passage between South America and Antarctica at ca. 32 Ma with formation of the cold Humboldt at ca. 30 Ma; union of North and South America at ca. 3.5 Ma; and all within the overlay of evolutionary processes. These processes generated a sequence of elements (e. g., species growing in moist habitats within an overall dry environment; gallery forests), early versions (e. g., mangrove communities without Rhizophora until the middle Eocene), and essentially modern versions of present-day New World ecosystems. As a first approximation, the fossil record suggests that early versions of aquatic communities (in the sense of including a prominent angiosperm component) appeared early in the Middle to Late Cretaceous, the lowland neotropical rainforest at 64 Ma (well developed by 58-55 Ma), shrubland/chaparral-woodland-savanna and grasslands around the middle Miocene climatic optimum at ca. 15-13 Ma, deserts in the middle Miocene/early Pliocene at ca. 10 Ma, significant tundra at ca. 7-5 Ma, and alpine tundra (paramo) shortly thereafter when cooling temperatures were augmented by high elevations attained, for example, in the Andes