The genus Pseudooneotodus (Drygant, 1974) is a genus of small and conical elements widely distributed from the Middle Ordovician to the Early Devonian throughout the world. Because of its unusual shape, Pseudooneotodus has long been considered enigmatic, and only in the late nineties of the last century the genus has been finally placed within conodonts according to histological data.

This study investigates possible similarities between Pseudooneotodus and Eurytholia (Sutton et al., 2001), an incertae sedis genus of enigmatic plates with a phosphate composition. An association of over one hundred specimens of Pseudooneotodus beckmanni and Eurytholia bohemica was analyzed from conodont residues in two distinct geographical areas: the Prague Basin (Požáry and Mušlovka sections, Bohemia, Czech Republic) and the Carnic Alps (Rauchkofel Boden section, Austria). Through an investigation that combines the use of optical and electron microscopy (including focused ion beam scanning electron microscopy), X-ray microdiffraction, and trace element (HFSE) analysis by mass spectrometry, differences between these fossil groups were observed and compared with data resulting from typical conodonts (Dapsilodus obliquicostatus, Panderodus unicostatus and Wurmiella excavata) recovered from the same samples.

Pseudooneotodus属（Drygant，1974 ）是一个小型圆锥形元素的属，从中奥陶世到早泥盆世广泛分布在世界各地。由于其不寻常的形状， Pseudooneotodus长期以来一直被认为是神秘的，直到上世纪九十年代末，根据组织学数据，该属才最终被归入牙形刺属。

这项研究调查了Pseudooneotodus和Eurytholia（Sutton 等人，2001）之间可能的相似之处，Eurytholia 是一种具有磷酸盐成分的神秘板的不确定的 Sedis属。对两个不同地理区域的牙形刺残留物中的一百多个 Pseudooneotodus beckmanni 和 Eurytholia bohemica 标本进行了分析：布拉格盆地（捷克共和国波扎里和穆斯洛夫卡地区）和卡尼克阿尔卑斯山（奥地利 Rauchkofel Boden地区）。通过结合使用光学和电子显微镜的研究（包括聚焦离子束扫描电子显微镜）、X射线微衍射和质谱微量元素（HFSE）分析，观察了这些化石组之间的差异，并与典型牙形刺（Dapsilodus obliquicostatus、Panderodus unicostatus和Wurmiella excavata）得到的数据进行比较）从相同的样品中回收。