New Cambrian and Lower Ordovician monoplacophorans from the Ozark Uplift, Missouri

Abstract

Seven new monoplacophoran genera and species are described and figured from Cambrian and Lower Ordovician strata of the Ozark Uplift of Missouri; Biloboconus frizelli, Ulrichoconus bonneterrense, Potosiplina delorensis, Gayneoconus echolsi, Irondalia irondalensis, Titanoplina meramecensis, and Wildernessia inexpectans. A new species of Kirengella, K. oregonensis, is described, and Hypseloconus compressus (Ulrich and Bridge, 1930, and H. expansus Stinchcomb, 1986, are assigned to the genus Kirengella. The morphology of Kirengella is compared to highly arched forms of the plated mollusk genus Preacanthochiton and is found to converge with them. Association with stromatolite reefs of both Kirengella and plated mollusks is noted.