The Late Cambrian (Steptoean; Furongian) trilobite Pseudokingstonia Palmer, 1965 in North America
The poorly known Late Cambrian (Steptoean; Furongian) genus Pseudokingstonia Palmer is revised using new material from the type area in west-central Utah. Previously undocumented features of pygidial morphology, including patterns of segmentation of the axis and pleural fields, and articulating flanges on the anterior margin, confirm that the genus is closely related to the dameselloidean Cheilocephalus Berkey and that together they constitute the family Cheilocephalidae Shaw. Pseudokingstonia is diagnosed by a high degree of cranidial and, especially, pygidial effacement, an exceedingly short anterior border on the cranidium, and steeply sloping pygidial borders. In addition to the Great Basin of Nevada and Utah, the genus is also known from Alberta, Arkansas, and Pennsylvania, and all occurrences are confined to the lower half of the late Steptoean Elvinia Zone.