Departmentof Biological Sciences, Kent State University, Kent, Ohio 44242; andFlorida Museum of Natural History, Gainesville, Florida32611.
Am J Bot. 1998 Oct;85(10):1426-38.
An assemblage of 17 identified and four unknown pollen and sporetypes is reported from the Pliocene Rio Banano Formation of southeasternCosta Rica. The most abundant are monolete fern spores, Palmae, cf.Antrophyum, Symphonia, Pelliceria,Lacmella (previously unreported in the fossil record),Alchornea, and Sabicea. These arrange into twopaleocommunities-mangroves and lowland tropical rain forest. Annual precipitation is estimated at near the present ∼3500 mm, butless seasonal, and the MAT (mean annual temperature) at ∼27°C. No pollen taxa representing distinctly arid or high-altitude vegetationwas being blown or washed into the coastal depositional basin, and nopollen grains were recovered of northern temperate elements that arepresent in Neogene floras to the north in Guatemala and southeasternMexico. These data are consistent with those from 12 other Miocene andPliocene palynofloras from northern Latin America, indicating the lateappearance of dry habitats and moderate paleoelevations and aprogressive southward introduction of northern temperate elements withlate Cenozoic cooling.
本文报告了哥斯达黎加东南部上新世 Rio Banano 地层中 17 种已鉴定和 4 种未知花粉和孢子类型的组合。最丰富的是单沟蕨类孢子、 Palmae、cf. Antrophyum、Symphonia、Pelliceria、Lacmella（以前在化石记录中未报道过）、Alchornea 和 Sabicea。这些组合成两个古群落——红树林和低地热带雨森林。估计年降水量接近目前的 3500 毫米，但季节性较差，MAT（年平均温度）约为 27°C。没有代表明显干旱或高海拔植被的花粉类群被吹或冲入沿海沉积盆地，也没有回收到在中美洲北部的危地马拉和墨西哥东南部的上新世植物群中存在的北温带元素的花粉粒。这些数据与来自北拉丁美洲的其他 12 个中新世和上新世孢粉组合的数据一致，表明干旱生境和中等古海拔的出现较晚，以及随着新生代冷却，北温带元素逐渐向南引入。
