Nyborg, T., Vega, F.J. & Filkorn, H.F. (2023) Validation of Costacopluma squiresi Nyborg, Vega & Filkorn (Crustacea: Brachyura: Retroplumidae) from the Pacific Slope, Paleocene of California, USA. Zootaxa, 5315 (5), 492–494.