Article: Morphology and phylogeny of Orbulinoides beckmannii (Saito 1962)

An examination of dissected specimens of the Eocene species Orbulinoides beckmannii (Saito 1962), formerly Porticulasphaera mexicana (Cusnman 1925), reveals certain morphological features not hitherto described. A study of the ontogeny of O. beckmannii and a comparison with the contemporaneous species Globigerapsis kugleri Belli, Loeblich and Tappan, and Globigerinatheka barri Bolli, Loeblich and Tappan, indicate that O. beckmannii is unlikely to be related to either of these species. It appears to have developed from some globorotaloid ancestor.