Anomalocaris, the most well‐known genus of the diverse stem euarthropod group Radiodonta, was first reported over 100 years ago from the Burgess Shale (Canada). This large Cambrian apex predator was later treated as occurring in the southern Great Basin (California and Nevada, USA). We re‐evaluate the systematic affinities of previously described material from the Pioche Formation, Nevada, and the Latham Shale, California, and describe the first radiodonts from the Pyramid Shale Member, Carrara Formation, California. Latham Shale (Cambrian Series 2, Stage 4, upper Dyeran) specimens previously assigned to Anomalocaris are reinterpreted as Ramskoeldia consimilis?, an amplectobeluid previously known only from the Chengjiang biota (Cambrian Series 2, Stage 3). Younger material from the Pioche and Carrara Formations (Series 2, Stage 4) is described as a new Anomalocaris species, A. magnabasis. This new species sheds light on the two‐part structure of Anomalocaris ventral endites, a potentially important character for distinguishing species, and reveals a sequence of five disarticulation stages for frontal appendages. The oldest Hurdia from Laurentia is also reported from the Pioche Formation (Cambrian Series 2, Stage 4). A changeover in taxonomic composition of the Radiodonta in the southern Great Basin is recognized: Anomalocaris replaces Ramskoeldia in the upper Dyeran, but it is not associated with a replacement of local olenelloid trilobites or seen in radiodonts elsewhere in Laurentia. These new data, combined with a summary of known radiodont occurrences, suggest that Anomalocaris species did not have large geographical distributions, when compared with other radiodonts such as Hurdia and Caryosyntrips.

中文翻译：

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Dyeran上段期间，来自美国大盆地南部的放射don的系统学，保存和生物地理学（寒武纪系列2，第4期）

Anomalocaris是多种茎类节肢动物类Radiodonta组中最著名的属，最早是在100多年前从Burgess页岩（加拿大）报道的。这种大型的寒武纪先天掠食者后来被视为发生在大盆地南部（美国加利福尼亚州和内华达州）。我们重新评估了内华达州Pioche组和加利福尼亚Latham页岩中先前描述的材料的系统亲和力，并描述了加州Carrara组金字塔页岩成员的第一个放射性同位素。以前分配给Anomalocaris的Latham页岩（寒武纪系列2，第4阶段，上Dyeran）标本被重新解释为Ramskoeldia consimilis②，以前仅在澄江生物群中才知道的两栖类动物（寒武纪系列2，第3期）。从皮奥奇和卡拉拉地层（系列2，第4阶段）年轻的材料被描述为一个新的奇虾种，A. magnabasis。这个新物种揭示了异齿龙腹侧白蚁的两部分结构，这是区分物种的潜在重要特征，并且揭示了额肢附肢的五个脱节阶段的序列。劳伦西亚（Lortia）的最古老的赫迪亚（Hurdia）也来自皮奥奇编队（寒武纪系列2，第4期）。人们已经认识到大盆地南部的放射齿动物的生物分类组成发生了变化：用Anomalocaris代替了Ramskoeldia在上部的Dyeran中，但是它与局部的类单核三叶虫的替换无关，或者与Laurentia的其他地方的放射线不可见。这些新的数据，已知radiodont出现的概要综合，认为奇虾与其他radiodonts如品种相比没有大的地理分布，Hurdia和Caryosyntrips。