Systematics and evolution of the brachiopod genusRhizothyrisin the Oligocene#x2014;Miocene of New Zealand

摘要

The terebratellid genusRhizothyrisThomson, 1915, has been restudied. The genus spans the period represented by Landon, Pareora, and Southland Series (OligoceneMiocene). Individual populations show a wide range of variation in trivial characters, making it difficult to delimit species. Of the 18 previously described species, 13 are placed in synonymy because they lack statistically significant differences from other species. One new speciesR. kokoamuensisis described, and five previously named species are reaffirmed. The stratigraphic history of the genus is presented and an interpretation of its evolution is attempted.