Diversity patterns and palaeoecology of benthic communities of the Kanosh Formation (Pogonip Group, Utah, western USA)
Diversity patterns and palaeoecology of benthic communities of the Kanosh Formation (Pogonip Group, Utah, western USA)
复制标题
DOI：
10.1007/s12549-020-00426-3
复制
发表时间：
2020-06
影响因子：
1.4
通讯作者：
R. Hofmann;J. Kehl
中科院分区：
文献类型：
--
作者：
R. Hofmann;J. Kehl
大平期至darriwillian Kanosh组是Pogonip群（美国西部大盆地）中化石含量最高的单元之一。它记录了所谓的大奥陶纪生物多样化事件（GOBE）的一个关键阶段，在此期间，许多海洋分支在较低的系统水平上多样化。然而，迄今为止还没有对该单元进行全面的古生态分析。基于Ibex类型区3个断面的新采集资料，我们重建了底栖生物群落，分析了多样性格局，并讨论了其对GOBE的意义。我们发现，就腕足类动物而言，整个地层的物种组成没有差异。底栖生物组合以shoshonor this michaelis为主，同时整个单元中存在着anomalorthis lonensis和anomalorthis utahens。三叶虫表现出更明显的相限制，在更近端的石灰岩中观察到kanoshiaand pseudoomeroides，而bathyurellusand pseudoolenoides则出现在细粒、低能量的沉积物中。骨骼石灰岩还记录了丰富的苔藓虫、棘皮动物和受壳动物的生物碎屑，表明内陆架带存在生态多样性和分层的群落。然而，就物种丰富度而言，这些类群中的大多数并不是特别多样化。这意味着“古生代动物群”典型成员的原则建立与分支的局部多样化无关。卡诺什动物群相对较低的栖息地多样性可能反映了环境限制，如高硅塑料输入率。此外，这些以大坪期为主的群落仍然是主要多样化发生前的基线动物群。
The Dapingian to Darriwilian Kanosh Formation is one of the most fossiliferous units of the Pogonip Group (Great Basin, western US). It records a critical phase of the so-called Great Ordovician Biodiversification Event (GOBE) during which many marine clades diversified on lower systematic levels. However, a comprehensive palaeoecological analysis has not been presented for this unit so far. Based on newly collected material from three sections in the type area at Ibex, we reconstruct benthic marine communities, analyse diversity patterns, and discuss its significance for the GOBE. We find no differences in species’ composition across the formation with respect to brachiopods. Benthic assemblages are dominated byShoshonorthis michaelis, alongside the presence ofAnomalorthis lonensisandAnomalorthis utahensisacross the whole unit. Trilobites show a more pronounced facies restriction with species ofKanoshiaandPseudomerabeing observed in more proximal limestone whereasBathyurellusandPseudoolenoidesoccur in fine-grained, low-energy deposits. The skeletal limestone also records abundant bioclasts of bryozoans, echinoderms, and receptaculitids, suggesting an ecologically diverse and tiered community being present in the inner shelf zone. However, most of these groups are not particularly diverse in terms of species richness. This implies that principle establishment of typical members of the “Palaeozoic Fauna” is not associated with a local diversification of clades. The comparably low habitat diversity of the Kanosh Fauna likely reflects environmental constraints such as high rates of siliclastic input. Additionally, these mainly Dapingian communities still represent a base-line fauna before the principal diversification took place.