Abstract

Crinoids are uncommon fossils in the Cenozoic. This scarcity means that even disarticulated elements are of note. Two species of the isocrinine Isselicrinus Rovereto are described from their disarticulated columns. Isselicrinus sp. A is from the upper Eocene Moritzian Stage of Tierra del Fuego. These crinoids have a robust column, varying from pentalobate (proximal?) to rounded pentagonal (distal?) in section and with consistently depressed areola petals. Isselicrinus sp. B is from the Lower Oligocene Juana Diaz Formation of Puerto Rico. This species is typified by slender pluricolumnals, always rounded pentagonal in section, and long noditaxes. Proximal and distal pluricolumnal morphologies are not distinguishable.