Earliest Silurian faunal survival and recovery after the end Ordovician glaciation: evidence from the brachiopods
Earliest Silurian faunal survival and recovery after the end Ordovician glaciation: evidence from the brachiopods
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DOI：
10.1017/s175569100807566x
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发表时间：
2007-09
影响因子：
1.2
通讯作者：
L. Cocks;R. Jia-yu
中科院分区：
文献类型：
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作者：
L. Cocks;R. Jia-yu
摘要对地球仪内志留纪早期的腕足动物群进行了调查，并将其划分为下鲁丹期和上鲁丹期。下鲁丹阶已知20个总科60属，上鲁丹阶已知25个总科87属。调查的29个地区横跨地球仪，既有纬度，也有经度。只有六个超科是Lazarus分类群，它们在奥陶纪和中Llandovery（Aeronian）以及后来的岩石中都是已知的，但在Rhuddanian中没有记录。这是令人惊讶的结果，因为许多先前的研究已经推断，鲁丹时期是一个动物非常稀少的时期。最新的奥陶纪（Hirnantian）冰河时代之后的全球变暖并没有迅速进行，至少在兰多弗里河可能存在冰盖。有一个明显的缺乏较低的Rhuddanian生物礁，即使在低palaeolatitudes，然而，生态恢复速度远远快于二叠纪末大规模灭绝事件。在此期间，将鲁丹大陆架动物群划分为界限分明的底栖生物组合的工作进展缓慢。
ABSTRACT Earliest Silurian (basal Llandovery) brachiopod faunas are surveyed and listed from around the globe, and divided between Lower Rhuddanian and Upper Rhuddanian occurrences. 60 genera are known from the Lower Rhuddanian within 20 superfamilies and there are 87 genera in 25 superfamilies in the Upper Rhuddanian. The 29 areas surveyed span the globe, both latitudinally and longitudinally. Only six superfamilies are Lazarus taxa which are known both from the Ordovician and Middle Llandovery (Aeronian) and later rocks but have not been recorded from the Rhuddanian. These are surprising results, since many previous studies have inferred that the Rhuddanian was a time of very sparse faunas. The global warming that followed the latest Ordovician (Hirnantian) ice age did not proceed quickly, with an ice-cap probably present through at least the Llandovery. There is a marked absence of Lower Rhuddanian bioherms even at low palaeolatitudes; however, the ecological recovery rate was far faster than that following the end-Permian mass extinction event. The partitioning of the Rhuddanian shelf faunas into well-defined benthic assemblages progressed slowly over the interval.