Middle Miocene Grasslands of Kenya

这是一项研究化石土壤和草的提议，作为东非中中新世草原及其在类人猿祖先进化中的作用的证据。自查尔斯·达尔文时代以来，草原在人类进化中的作用就一直存在争议，肯尼亚中中新世(14 Ma)草原的存在也一直存在争议。现在有几条证据汇聚在一起，表明肯尼亚存在中中新世草原：(1)化石土壤和哺乳动物牙齿中碳酸盐的同位素研究表明热带草地植被，(2)类似于现代草原(软土)的化石土壤，(3)在羚羊化石上的放牧口吻和抓齿，以及(4)具有丰富的蛋白石(植硅体)和稀少的气孔(气孔)的化石草。这些发现在某些情况下只是基于初步研究，现在需要推广到更多分布在肯尼亚西南部的中中新世(13-16 Ma)遗址：Ombo、Majiwa、Maboko、Nyakach、Fort Ternan、Serek和Kapsibor。将对每个地点的化石土壤进行描述和采样，以便进行实验室分析。化石草也将被收集并送回实验室进行使用计算机数据库进行鉴定所需的显微镜检查。还计划对草和化石土壤进行同位素研究，以确定存在的草和植被的种类(C3或C4草)。该项目以之前成功项目的亮点为基础，提供了东非最早草原的生理、自然、植物组成和范围的详细信息。

This is a proposal to study fossil soils and grasses as evidence for Middle Miocene grasslands in East Africa and their role in the evolution of apelike ancestors of humans. The role of grasslands in human evolution has been debated since Charles Darwin's day, and the existence of Middle Miocene (14 Ma) grasslands in Kenya has continued to be controversial. Several lines of evidence now converge to indicate Middle Miocene grasslands in Kenya: (1) isotopic study of carbonate in fossil soils and apatite of mammalian teeth indicating tropical grassy vegetation, (2) fossil soils similar to those of modern grasslands (Mollisols), (3) grazing muzzle and tooth scratching on antelope fossils, and (4) fossil grasses with the abundant opal (phytoliths) and scarce pores (stomates) of open country grasses. These findings are in some cases based on only preliminary studies and now need to be extended to more sites of Middle Miocene age (13-16 Ma) scattered through southwestern Kenya: Ombo, Majiwa, Maboko, Nyakach, Fort Ternan, Serek and Kapsibor. Fossil soils at each site will be described and sampled for laboratory analysis. Fossil grasses will also be collected and returned to the laboratory for the microscopic examination needed to identify them using a computer database. Also planned are isotopic studies of the grasses and fossil soils to determine the kinds of grasses and vegetation present (C3 or C4 grasses). This project builds on the highlights of a previously successful program to provide a detailed view of the physiology, nature, botanical composition and extent of the earliest East African grasslands.