The Middle Cambrian Eodiscoid trilobite Dawsonia oelandica (Westergård, 1936)

The eodiscina comprises small, isopygous trilobites with either two or three thoracic segments. Small eyes may be present, but several genera and species lack visual organs. Eodiscoids are characteristic elements of many Cambrian faunas and are important for correlations of upper Lower Cambrian and lower Middle Cambrian strata (e.g., Robison et al., 1977; Ahlberg and Bergström, 1993; Geyer and Shergold, 2000; Fletcher, 2003).