Collaborative Investigation of Earliest Crayfish: Paleobiologic, Paleoecologic, and Paleoclimatic Implications

OPP 9614709 Isbell：OPP 9615045 Babcock：OPP 9614989摘要在1995年至1996年的南极洲夏季野外季节，在南极洲沙克尔顿冰川地区发现了已知最古老的小龙虾化石和已知的最古老的小龙虾洞穴之一。该奖项支持一项合作的跨学科研究，以扩大这些发现。小龙虾爪是在2.8亿至3亿年前冰川环境中沉积的上石炭统至下二叠世塔组中发现的；这一发现将小龙虾的首次出现时间推迟了6500万至7500万年。小龙虾洞穴是在大约2.4亿年前沉积的下三叠统弗雷莫地层中发现的。它们的丰富性和复杂性表明，小龙虾在其漫长的历史中很早就形成了洞穴行为。这项研究的目的是从南极洲收集更多的小龙虾遗体和遗迹化石，利用这些化石进一步了解南极洲部分地区在晚石炭世-早二叠世和早三叠世期间的沉积条件，并研究淡水星形十足类(小龙虾)的早期进化和洞穴历史。具体地说，工作计划是：1)在宝塔组中寻找更多的小龙虾和小龙虾洞穴化石；2)解释宝塔组中小龙虾的生活方式，并将其与小龙虾的形态联系起来；3)重建小龙虾所在岩石记录的沉积环境和古气候；4)在弗莱莫组的洞穴中寻找小龙虾；5)定量描述弗莱莫组中的洞穴；6)将晚石炭世至早二叠世小龙虾和洞穴的形态和行为与早三叠世及更晚的那些进行比较。这项研究将阐明小龙虾的进化和行为历史。现代小龙虾在许多不同的水生生态系统中对能量流动、生物种类组成和生物丰度等参数起着重要的控制作用。这项拟议的研究将提供关于这种环境和行为多样化如何以及何时发生的信息，以及增加对晚古生代和早中生代古气候的了解。

Miller: OPP 9614709 Isbell: OPP 9615045 Babcock: OPP 9614989 Abstract During the 1995-96 Austral summer field season the oldest known fossil crayfish and one of the oldest known occurrences of fossil crayfish burrows were found in the Shackleton Glacier area of Antarctica. This award supports a collaborative, interdisciplinary study to expand on these discoveries. The crayfish claw was found in the Upper Carboniferous to Lower Permian Pagoda Formation deposited in glacial environments 280 to 300 million years ago; the discovery pushes back the first occurrence of crayfish 65 to 75 million years. The crayfish burrows were found in the Lower Triassic Fremouw Formation deposited approximately 240 million years ago. Their abundance and complexity indicate that crayfish developed burrowing behavior early in their long history. The objectives of the study are to collect additional crayfish body and trace fossils from Antarctica, to use these fossils to develop further insight into the depositional conditions in parts of that continent during intervals of the Late Carboniferous- Early Permian and the Early Triassic, and to study the early evolutionary and burrowing history of freshwater astacoid decapods (crayfish). Specifically, the work plan is: 1) to search for more fossil crayfish and crayfish burrows in the Pagoda Formation; 2) to interpret the way of life of the crayfish in the Pagoda Formation and relate it to the crayfish morphology; 3) to reconstruct the depositional environment and paleoclimate recorded by the crayfish-bearing rocks; 4) to search for crayfish within burrows in the Fremouw Formation; 5) to quantitatively describe the burrows in the Fremouw Formation; and 6) to compare the morphology and behavior of Late Carboniferous to Early Permian crayfish and burrows to those of the Early Triassic and later. This study will elucidate the evolutionary and behavioral history of crayfish. Modern crayfish exert an important control on paramet ers such as energy flow, biotic species composition, and biotic abundance in many different aquatic ecosystems. This proposed study will yield information about how and when this environmental and behavioral diversification took place, as well as increase understanding of the late Paleozoic and early Mesozoic paleoclimates.