The middle Cambrian (Miaolingian Series; Wuliuan Stage) Spence Shale of Utah and Idaho preserves a diverse assemblage of biomineralized and soft-bodied taxa. Among the rarest specimens of this fauna are palaeoscolecid worms. Until recently, only one specimen was known from the Spence Shale, the holotype specimen of Palaeoscolex ratcliffei Robison, 1969, later included in the genus Wronascolex. This specimen is preserved as part and counterpart but missing both the posterior and anterior terminations. A new specimen, discovered by Riley Smith, preserves an everted proboscis with spines. Based on new data collected using scanning electron microscopy and energy dispersive X-ray spectrometry (SEM–EDS), and optical microscopy, the species is thought to represent a new genus, Utahscolex gen. nov., rather than a species of Palaeoscolex or Wronascolex as previously suggested. The new genus differs from the other two genera in the lack of node ornamentation of the plates, as well as the absence of microplates and platelets. Based on this case study, it is recommended that future revisions of palaeoscolecid taxonomy require knowledge of plate, platelet, and microplate ornamentation, as well as the arrangement of the plates, platelets, and microplates on the cuticle. In addition to the improved morphological information provided by the new specimen, it also advances our knowledge of the taphonomic pathways in the Spence Shale and in palaeoscolecid worms in general. The preservation of the plates of the two specimens of this species differ in elemental composition and somewhat in quality. While both the holotype and new specimen show localized magnesium and phosphorus within the plates, the holotype has a substantial iron component, whereas the new specimen instead shows elevated calcium. In addition, kerogenization, pyritization, aluminosilicification, and phosphatization can be observed throughout the specimen. The preservation varies not only between the specimens, but also within, demonstrating the high variability of preservational pathways within a Burgess Shale-type deposit, and providing insights into the circumstances that lead to soft-bodied preservation in the Spence Shale.

犹他州和爱达荷州的中寒武纪（苗岭阶；五六阶）斯潘斯页岩保留了多种生物矿化和软体类群。在这种动物中最稀有的标本中有古鲨蠕虫。直到最近，从Spence页岩中仅获知一个标本，它是1969年Palaeoscolex ratcliffei Robison的完整型标本，后来被列入Wronascolex属。该标本作为一部分和对应物保存，但缺少后部和前部终止点。莱利·史密斯（Riley Smith）发现了一个新标本，保留了带有刺的长鼻。根据使用扫描电子显微镜和能量色散X射线光谱仪（SEM-EDS）和光学显微镜收集的新数据，该物种被认为代表了一个新属，犹他州斯科莱克斯将军 十一月，而不是古希腊或Wronascolex的物种如前所述。该新属与其他两个属的不同之处在于缺少板的节装饰，以及没有微板和血小板。基于此案例研究，建议以后修订的古骨类分类学需要了解板块，血小板和微孔板的装饰，以及板，血小板和微孔板在表皮上的排列。除了新标本提供了改进的形态学信息外，它还提高了我们对Spence页岩和古骨鞘虫蠕虫中的透声途径的认识。该物种的两个标本的板的保存在元素组成和质量上有所不同。完整样本和新样本都显示了板中的局部镁和磷，整体型具有大量的铁成分，而新样品则显示出较高的钙。此外，在整个样品中都可以观察到干酪根，黄铁矿化，铝硅化和磷化。保存不仅在标本之间而且在标本之间也各不相同，这表明Burgess页岩型矿床中保存途径的高度可变性，并提供了在Spence页岩中导致软质保存的环境的见解。