Asymptoceras (original) (raw)

Asymptoceras is a genus of aipoceratids (Nautiloidea) similar to Aipoceras but tightly coiled and with only part of the body chamber divergent from the previous whorl. Shell evolute, expanding fairly rapidly; umbilicus open, perforate; whorl section ovoid to subquadrate. Asymptoceras is known from Mississippian (Lower Carboniferous) sediments in Europe and North America.