Reconsidering the 'phyllocarid' from the Wade Creek Formation

The fossil record of phyllocarids in Australia is decidedly limited, with only a few specimens known from Ordovician to Devonian deposits. Therefore, the identification of examples from older deposits would uncover more facets of Gondwanan crustacean evolution. Here, a supposed phyllocarid reported by Chapman (1925) from the Mount John Shale Member of the Wade Creek Formation is reconsidered. We conclude that the 'phyllocarid'-like structure is somewhat morphologically comparable to traces ascribed to the activity of bivalved arthropods. However, as the Mount John Shale Member is likely Mesoproterozoic in age, the most parsimonious explanation is that the structure is a cast created by abiotic activity. Re-examination of such specimens represents a useful approach to clarifying previous misidentifications in the literature and is an important application of historically valuable specimens and collections.