High-Resolution Chronostratigraphic Constraints on the Biogeography of New Tetrapod Assemblages from Triassic Paleoequatorial Rift Basins of Southeastern North America

该项目的目标是为北美东部最南端的三叠纪裂谷盆地，特别是深河和丹河盆地，以及较小程度上的里士满和泰勒斯维尔盆地，建立高分辨率的年代学、地层学和古地理框架。这些盆地包括唯一的出露大陆序列限制已在赤道地带的三叠纪盘古大陆。一个精确的时空框架的发展，促使令人兴奋的发现意外丰富，似乎地方性的四足动物组合，从这些盆地，建议晚三叠世动物群演化的模式的新的解释。这些动物群包含数量惊人的联会动物（双齿兽、双齿兽和高级犬齿兽），它们将这些古赤道组合与北方三叠纪裂谷的同时代组合以及美国西南部的经典钦勒群区分开来。此外，这些动物群的元素提供了相互矛盾的生物地层学信息，需要独立的机制来评估它们的年龄和相互关系。我们建议使用古地磁和旋回地层的手段，把这些新的和以前发现的组合到一个严格约束的古地理和时间框架相关的定义明确的纽瓦克盆地的时间尺度，通过以前的NSF资助的工作。我们预计，该项目将有重大影响的速率和三叠纪陆地动物群的变化，以及三叠纪-侏罗纪大规模灭绝的特点和后果的分类和地理格局。

The objective of this project is to develop a high-resolution chronologic, stratigraphic, and paleogeographic framework for the southernmost exposed Triassic rift basins in eastern North America, specifically the Deep River and Dan River basins and to a lesser extent, the Richmond, and Taylorsville basins. These basins comprise the only outcropping continental sequences constrained to have been in the equatorial zone of Triassic Pangea. The development of a precise spatiotemporal framework is prompted by the exciting discovery of unexpectedly rich, seemingly endemic tetrapod assemblages from these basins that suggest new interpretations of the pattern of Late Triassic faunal evolution. These faunules contain surprisingly large numbers of synapsids (dicynodonts, traversodonts, and advanced cynodonts) that differentiate these paleoequatorial assemblages from coeval ones of the more northern Triassic rifts, as well as those from the classic Chinle Group of the American Southwest. In addition, elements of these faunules provide conflicting biostratigraphic information requiring independent mechanisms for assessing their age and correlation. We propose to use paleomagnetic and cyclostratigraphic means to place these new and previously discovered assemblages into a tightly constrained paleogeographic and temporal framework correlated to the well-defined Newark Basin time scale developed through previous NSF-funded work. We anticipate that this project will have major implications for the rates and taxonomic and geographic patterns of Triassic terrestrial faunal change, as well as the character and consequences of the Triassic-Jurassic mass extinction.