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The Beginning of the Mesozoic: Paleoecological and Paleo- environmental Analysis of the Lower Triassac Virgin Limestones (Nevada and Utah)

中生代的开始：下三叠纪原始石灰岩（内华达州和犹他州）的古生态和古环境分析

基本信息

批准号：
9004547
负责人：
David Bottjer
金额：
$ 9万
依托单位：
University of Southern California
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
1990
资助国家：
美国
起止时间：
1990-07-01 至 1993-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9004547&HistoricalAwards=false
关键词：
Beginning Mesozoic Paleoecological Paleo environmental

项目摘要

The mass extinction at the end of the Permian has been established as the greatest perturbation which the Earth's biosphere has experienced since the origin of metazoan life. Although relatively little is known about the cause of this mass extinction, even less is known on biotic conditions in its aftermath or the nature of biotic recovery from this event. Fossil faunas and limestones in the Lower Triassic Virgin Member of the Moenkopi Formation (southern Nevada and southwestern Utah), deposited 5 my after the end of the Permian, present an opportunity to learn how benthic faunas in shallow marine carbonate environments were faring in this recovery interval. Preliminary study of the Virgin limestones indicates deposition in a normal marine environment with benthic macroinvertebrate assemblages of relatively low species richness. Of potentially great significance are intervals of apparent normal marine stromatolites, which may represent temporary expansion from marginal marine refugia into normal marine settings due to restriction of grazers, caused by the mass extinction. Evidence for the beginning of recovery is demonstrated through the presence of abundant specimens of the earliest articulate crinoid, which had evolved from some unknown Paleozoic inadunate that survived the crisis. Research will illuminate the way in which biotas recover from mass extinctions.

二叠纪末期的大灭绝这是地球上最大的扰动，自后生动物生命起源以来，生物圈经历了许多变化。尽管我们对这团物质的成因知之甚少灭绝，甚至更少的是已知的生物条件，这一事件的后果或生物恢复的性质。下三叠统原生段的化石动物群和灰岩 Moenkopi组（内华达州南部和西南部犹他州），沉积在二叠纪结束后的5百万年，目前，有机会了解浅海底栖动物碳酸盐岩环境在这一恢复期表现良好。对原始石灰石的初步研究表明在有底栖大型无脊椎动物正常海洋环境中物种丰富度相对较低的群落。潜在具有重要意义的是， stromatectomy，这可能代表暂时的扩张，边缘海洋避难所进入正常的海洋环境，限制食草动物，由大规模灭绝引起。证据复苏的开始是通过最早的有孔虫标本海百合，它是从一些未知的古生代无水植物进化而来的，在危机中幸存下来研究将阐明生物体从大规模灭绝中恢复过来。