Survivorship and recovery of early triassic tetrapods following the permo-triassic extinction event

二叠纪-三叠纪灭绝事件后早期三叠世四足动物的生存和恢复

• 批准号: 288126-2007
• 负责人: Modesto, Sean
• 金额: $ 2.21万
• 依托单位: Cape Breton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=363642
• 关键词: Survivorship; recovery; early; triassic; tetrapods

Of the five known mass extinction events, the Permo-Triassic extinction event is regarded unanimously as the most severe in Earth history. The consensus view has been that 70-90% of species became extinct 251 million years ago. Such estimates of high species mortality were based on ranks-based studies of low taxonomic resolution (family-level groups). My own investigations, using phylogenetic studies of higher resolution (species and genera), suggest that terrestrial vertebrates (tetrapods) experienced low extinction pressure during the Permo-Triassic extinction event.     To date I have examined the Permo-Triassic boundary survivorship of amniotes (mammals, reptiles, birds, and their fossil relatives). The two reptile groups examined, procolophonoid parareptiles and archosauromorph diapsids, exhibit roughly 29% and 14-17% extinction, respectively. Current work on therocephalians, a group of synapsid amniotes, suggests that they experienced 43% extinction. Judging from published phylogenies, cynodont synapsids suffered 40-50% extinction. The evidence so far suggests that the amniote extinctions were not as severe as commonly believed, and that the effects of extinction were not even handed among the groups.     Procolophonoids and therocephalians are the most diverse and, after lystrosaurids, the most commonly encountered amniotes in the Karoo Basin of South Africa, the country with the best fossil record for studying the effect of this extinction event on tetrapods. I propose to continue my phylogenetically-based research on the survivorship of the above mentioned amniote groups through the Permo-Triassic boundary. I will expand my program by looking at the post-extinction survivorship of amniotes in the Karoo, in light of a recent suggestion that a "survivor fauna" succumbed to a second pulse of extinctions that followed the main extinctions at the Permo-Triassic boundary. The results of the study will help to elucidate the differences of effect of the Permo-Triassic extinctions on tetrapods with respect to that on plants and marine invertebrates, which experienced a single extinction pulse followed by a recovery period of 4-5 million years.

在已知的五次大灭绝事件中，二叠纪-三叠纪灭绝事件被一致认为是地球历史上最严重的灭绝事件。普遍的观点是，70-90%的物种在2.51亿年前灭绝。物种死亡率高的这种估计是基于对低分类分辨率（科一级群体）的等级研究。我自己的调查，使用更高分辨率的系统发育研究（种和属），表明陆生脊椎动物（四足动物）经历了低灭绝压力在二叠纪-三叠纪灭绝事件。 到目前为止，我已经研究了二叠纪-三叠纪界线的恐龙（哺乳动物、爬行动物、鸟类及其化石亲属）的生存情况。研究的两个爬行动物类群，原喙类副爬行动物和初龙型双足类，分别表现出大约29%和14-17%的灭绝。目前对兽头目（一组突触纲动物）的研究表明，它们经历了43%的灭绝。从已发表的化石来看，犬齿类联会动物灭绝了40-50%。到目前为止的证据表明，物种灭绝并不像人们普遍认为的那样严重，物种灭绝的影响甚至没有在群体之间传递。 原颈龙类和兽头龙类是最具多样性的，仅次于水龙类，是南非卡鲁盆地最常见的恐龙，南非拥有最好的化石记录来研究这次灭绝事件对四足动物的影响。我建议继续我的生物遗传学为基础的研究，通过二叠纪-三叠纪边界的生存上述的古生物群。我将扩大我的计划，看看后灭绝的生存在卡鲁，根据最近的建议，一个“幸存者动物群”屈服于第二个脉冲的灭绝，其次是在二叠纪-三叠纪边界的主要灭绝。研究结果将有助于阐明二叠纪-三叠纪灭绝对四足动物影响与植物和海洋无脊椎动物影响的差异，后者经历了一个单一的灭绝脉冲，随后经历了400 - 500万年的恢复期。