Abstract This study adds new data to complete the taxonomic revision of arthrodire placoderms from the Early Devonian of the Prague Basin (Czech Republic). It focuses on re-describing arthrodire specimens from the Emsian strata published more than a hundred years ago and associating them with unpublished material. The observations contradict previous taxonomic determinations of the Emsian arthrodires, which distinguished four species of three genera. Only one new genus and species is recovered—Johannaspis bohemicus (Barrande, 1872). The previous taxonomic splitting of the material into various genera is explained as a factor of specific taphonomical preservation in different localities of the Prague Basin. Another factor enabling the artificial splitting was the present location of the material in different institutions around the world. Together with Antineosteus rufus Vaškaninová & Kraft, 2014 based on previously unpublished specimens, they are the only two placoderm species known from the Emsian of the Prague Basin. Both are assigned to the homostiid arthrodires—large suspension feeders. The abundance of the Emsian placoderm fauna is very low in the Prague Basin; only a few specimens are known from each locality. However, they occur in a number of localities of Emsian age in the Prague Basin and in different environments, from very shallow (A. rufus) to relatively deeper marine environments, with all the occurrences being in limestones. The palaeogeographical distribution of homostiid arthrodires in the late Early Devonian was limited to tropical and subtropical shallow marine environments mainly in the southern hemisphere. In the Middle Devonian, the homostiids are no longer recorded from the northern continental margin of Gondwana including the Prague Basin area. However, they appear in Laurussia, Siberia and eastern Gondwana. The disappearance of environments with abundant food resources favourable for these large suspension feeders in the Prague Basin area could be related to the narrowing of the Rheic Ocean and gradual emerging of dry land as an early manifestation of the proceeding Variscan orogeny. This specific local palaeogeographical development of the Prague Basin area is considered the main reason for the significant decrease in diversity and abundance of placoderm fauna, which is in contradiction to the general trend. Valéria Vaškaninová [va.vaska@gmail.com], Institute of Geology and Palaeontology, Faculty of Science, Charles University, Albertov 6, Prague, 128 43, Czech Republic.

中文翻译：

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homostiid arthrodire 的新属有助于修正布拉格盆地早泥盆世的板皮多样性

摘要 本研究增加了新数据，以完成对布拉格盆地早泥盆世（捷克共和国）的节肢动物板皮动物的分类学修订。它的重点是重新描述一百多年前发表的 Emsian 地层的节肢动物标本，并将它们与未发表的材料联系起来。这些观察结果与之前对 Emsian arthrodires 的分类决定相矛盾，后者区分了三个属的四个物种。仅恢复了一种新属和种——Johannaspis bohemicus (Barrande, 1872)。先前将材料分类为不同属的分类被解释为布拉格盆地不同地区特定埋藏保存的一个因素。另一个促成人工分裂的因素是材料在世界各地不同机构的当前位置。与 Antiineosteus rufus Vaškaninová & Kraft，2014 年基于以前未发表的标本一起，它们是布拉格盆地 Emsian 已知的仅有的两种板皮动物物种。两者都被分配到homostiid arthrodires——大型悬浮饲养者。Emsian placoderm 动物群在布拉格盆地的丰度非常低；每个地方只知道少数标本。然而，它们出现在布拉格盆地 Emsian 时代的许多地方和不同的环境中，从非常浅的 (A. rufus) 到相对较深的海洋环境，所有发生在石灰岩中。早泥盆世晚期拟节肢动物的古地理分布仅限于热带和亚热带浅海环境，主要分布在南半球。在中泥盆世，在冈瓦纳大陆的北部大陆边缘，包括布拉格盆地地区，不再有类人猿的记录。然而，它们出现在劳鲁士、西伯利亚和冈瓦纳东部。布拉格盆地地区有利于这些大型悬浮饲养者的丰富食物资源环境的消失可能与流变洋变窄和旱地逐渐出现有关，这是进行中的瓦利斯坎造山运动的早期表现。布拉格盆地地区这种特定的局部古地理发展被认为是盾皮动物群多样性和丰度显着下降的主要原因，这与总体趋势相矛盾。Valéria Vaškaninová [va.vaska@gmail.com]，地质与古生物学研究所，科学学院，查理大学，阿尔贝托夫 6，布拉格，128 43，