Pliocene to Pleistocene Fauna of Central America: The Isthmus as a Biogeographic Barrier

巴拿马地峡大约出现在280万至320万年前。它形成了一个主要的海洋屏障，将美洲热带海洋分成了两个新的领域，它们的海洋环流、盐度、温度和营养物质截然不同。它还连接了两个迄今分离的、不同的陆地动物群和植物群。这可能是过去6000万年来最重要的海洋、气候和生物地理事件。该项目将定位和描述地峡两侧的沉积层，其年代从大约600万年到现在。利用微观和宏观的化石，科茨博士和他的同事们将测定沉积物的年代，并试图确定地峡最终关闭的准确时间。该项目包括1)收集和切片测量野外考察，2)大规模样品处理以提取标本，3)识别和描述物种，4)确定地层和化石的年龄和古环境，5)将所有这些信息输入专门设计的计算机数据库。所建立的数据库将是独特的，因为它有可能解决生物学中的一些基本问题，例如与具体的重大环境事件有关的各种海洋动植物物种起源和灭绝的原因和模式。

The Isthmus of Panama emerged about 2.8-3.2 million years ago. It formed a major marine barrier splitting the American tropical ocean into two new realms with profoundly different ocean circulation, salinity, temperature and nutrients. It also connected two hitherto separate and different terrestrial faunas and floras. It was perhaps the single most important oceanic, climatic and biogeographic event in the last 60 million years. This project will locate and describe the sedimentary strata on each side of the isthmus dating from about 6 million years to the present. Using micro and macro fossils Dr. Coates and his colleagues will date the sequence of sediments and attempt to establish the precise time of final closure of the isthmus. The project entails 1) collecting and section measuring field expeditions, 2) large-scale sample processing to extract specimens, 3) identifying and describing species, 4) assigning ages and paleoenvironments to the strata and fossils, 5) entering all this information into a specially designed computer database. The database generated will be unique in its potential to address some fundamental questions in biology, such as the causes and patterns of origination and extinction of species in a variety of marine animals and plants, related to a specific major environmental event.