Collaborative Research: A New Paleogene Fauna from the Chilean Andes: A Critical Interval in South American Mammalian History

Andre Wyss（加州大学圣巴巴拉分校）和Mark Norell（纽约美国自然历史博物馆）将进行合作研究。在几乎整个新生代都与其他大陆隔绝的南美洲，发展出了一种非常独特和特有的陆地哺乳动物，一个多世纪以来，进化生物学家和古生物学家一直对这种动物感兴趣。来自智利中部安第斯山脉的一种非凡的新动物群，属于南美洲第三纪记录中最鲜为人知的时期，大约1500万年后穆斯特桑（始新世中期），前迪斯丹（始新世中期）。晚渐新世)段。由于这一跨度与一个主要的动物群转变相吻合，它对于理解几个长期存在的问题是至关重要的，这些问题是关于南美本土主要哺乳动物化石群体之间的系统发育关系的。因此，新的动物群标志着第一个有代表性的动物群，澄清了大陆始新世-渐新世的过渡。除了具有重要的古生物意义外，这些新的动物群对解释安第斯山脉中部一大片地区的地层学和构造历史也有重要意义。这项研究有三个重点。第一项措施包括继续开展有力的实地收集和侦察计划。第二个问题是如何描述这种多样化的、保存完好的、高度出乎意料的化石组合，并将其成分置于一个严格的系统发育框架中。第三是将该发现置于一个高度整合的地质年代学背景中。为此目的，将采用生物年代学、磁地层学和放射性同位素方法。

Collaborative research will be conducted between Andre Wyss (University of California, Santa Barbara) and Mark Norell (American Museum of Natural History, NY). Isolated from other continents for nearly all of the Cenozoic, there developed in South America a highly peculiar and endemic land mammal fauna that has captured the interest of evolutionary biologists and paleontologists for more than a century. An extraordinary new fauna from the Andes of central Chile falls within what previously represented the most poorly known span of the South American Tertiary record, an approximately 15 million year post-Mustersan (middle Eocene), pre-Deseadan (?late Oligocene) interval. As this span coincides with a major faunal transition, it is crucial to the understanding of several long-standing problems of phylogenetic relationship among the major groups of indigenous South American fossil mammals. The new fauna thus marks the first well represented fauna clarifying the Eocene-Oligocene transition from the continent. In addition to being of major paleobiologic importance, the new fauna bears significantly on interpretation of the stratigraphy and tectonic history in a very broad segment of the central Andes. This study has three points of focus. The first involves a continued vigorous field collection and reconnaissance program. The second concerns description of this diverse, well preserved, and highly unexpected fossil assemblage, and placement of its constituents into a rigorous phylogenetic framework. The third consists of the discovery's placement into a highly integrated geochronologic context. To that end, biochronologic, magnetostratigraphic, and radioisotopic methods will be employed.