Bolboforma — an overview

• Published in: Paläontologische Zeitschrift
• Main Authors: Spiegler, Dorothee, Spezzaferri, Silvia
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2005
• Subjects: Campbell Plateau; Hatton-Rockall Basin; Indian; Kerguelen; Labrador Sea; North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/31861/; https://oceanrep.geomar.de/id/eprint/31861/1/Spiegler_2005.pdf; https://doi.org/10.1007/BF03021760

A summary of the present knowledge of Bolboforma is presented in this paper. The genus Bolboforma contains a diverse group of marine, mostly single-chambered enigmatic microfossils (phytoplankton, possibly Chrysophyta) which produced calcitic monocrystalline spheroidal tests with or without inner cysts and with various types of ornamentation. The genus Bolboforma occurs in the time interval between late Early Eocene to Late Pliocene, at middle and higher latitudes, and thus, has not been recorded in Quaternary to Recent Sediments. The genus is represented globally, but the first and the last occurrence of the genus appear to be spatially diachronous in both hemispheres. Bolboforma started in the southern hemisphere at the Campbell Plateau (SW Pazific) during the Early Eocene approximately 53 Ma ago, and the genus lived there until latest Miocene times (5.3 Ma at the Kerguelen Plateau, Southern Indian Ocean). The first occurrence of Bolboforma in the northern hemisphere is observed in Upper Eocene Sediments (ca. 36.5 Ma) in the Labrador Sea (North Atlantic), and its youngest occurrence is observed in the Hatton-Rockall Basin (North Atlantic) in the Late Pliocene at 2.84 Ma. Well established and common species permit the definition of nineteen Bolboforma zones/subzones. Not all of these are observed in both hemispheres. In the southern hemisphere all four Paleogene zones, but only eight Neogene zones are present, in the northern hemisphere only one Paleogene zone, but fourteen Neogene zones have been determined. Bolboforma distribution, which appears to be broadly bipolar in temperate to cool regions at middle to higher latitudes, aso seems to be linked to the evolution of surface watermasses and their boundaries.