Bateman, Jasper1, Hegna, Thomas Arthur2r>
(1) Department of Geology and Environmental Sciences, SUNY Fredonia, Fredonia, NY, USA, (2) Department of Geology and Environmental Sciences, SUNY Fredonia, Fredonia, NY, USA,
Abstract:
Notostracans are often called “living fossils,” however, the taxonomy of extinct notostracans remains poorly resolved, as highlighted by Geyer et al. (2024). Fossil notostracans are known from two localities in the United States; the Permian-aged Enid Formation in Oklahoma and the Triassic-aged Bull Run Formation in Virginia. Both occurrences were previously assigned to the extant genus Triops, but these identifications were made with a limited critical evaluation of diagnostic morphology. Re-examination of the Permian Oklahoma material shows that it belongs to the genus Olesenocaris, previously only known from the Triassic of France. The Virginia specimens represent a new species of the genus Apudites. These revisions indicate that previous assignments to Triops were insufficiently supported. This reinforces the need for further rigorous systematic revision of fossil notostracans. Although notostracan body plans are morphologically conservative through time, they were not evolutionarily static. Detailed anatomical and systematic studies demonstrate that the extant Triops cancriformis lacks a confirmed fossil record, undermining its long-standing characterization as a “living fossil.”