On the Demise of the Early Paleogene Morozovella velascoensis Lineage: Terminal

• Main Authors: Progenesis In The Planktonic Foraminifera, D. Clay Kelly, Timothy J. Bralower, James C. Zachos
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Pacific; Planktonic foraminifera
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.567.2017; http://www.es.ucsc.edu/~jzachos/pubs/KBZ_2001.pdf

The extinction of the Morozovella velascoensis lineage, a group of planktonic foraminifera that dominated tropical assemblages for;6.3 m.y., is investigated using an upper Paleocene/lower Eocene section from the central Pacific Ocean (ODP Site 865). Uppermost stratigraphic occurrenc-es of the lineage consist solely of diminutive M. edgari, a species roughly half the size of its ancestor, M. velascoensis. Eigenshape analysis indicates that adult specimens of M. edgari are morphologically similar to small, presumably ju-venile, forms of M. velascoensis. The overall stratigraphic succession, where the uppermost occurrences of a lineage are represented by relict populations of minute, juvenilized forms, is consistent with a process called ‘‘terminal progen-esis.’ ’ Various lines of evidence indicate that stress-induced size reduction foreshadowed the extinction of other plank-