First record of the echinoid genus Orthopsis COTTEAU, 1864 from the Kössen Formation (Rhaetian, uppermost Triassic) of Vorarlberg (Austria), with description of a new species.

A new species of sea urchin is described from deposits assigned to the Kössen Formation (uppermost Triassic, Rhaetian) of Vorarlberg, Austria. A comparison with other fossil echinoids has shown that the available specimen can be assigned to the genus Orthopsis. Moreover, several distinctive features of the material allow it to be described here as a new species, O. kiseljaki sp. nov. The new species is the stratigraphically earliest representative of the genus and the first to be recorded from the Triassic, although a considerably higher family level diversity of Echinoidea does not occur until the beginning of the Jurassic Period. The new finding from the Kössen Formation implies that the Rhaetian might be an important time for the diversification of echinoids, particularly with regard to the echinacean Orthopsis. [ABSTRACT FROM AUTHOR]