Stratigraphic Record of the Neogene Globorotalid Radiation (Planktonic Foraminiferida)

Abstract

Cifelli, Richard, and George Scott. Stratigraphic Record of the Neogene Globorotalid Radiation (Planktonic Foraminiferida). Smithsonian Contribu¬ tions to Paleobiology, number 58, pages 101, 43 figures, 1986.-The histories of lineages forming the Neogene globorotalid radiation in the planktonic foraminifera are reconstructed primarily from stratigraphic distributions. Data on major taxa are synthesized, with particular reference to the devel¬ opment of shell design, and related to biogeograpy and evolutionary strategies. The radiation was established about the base of the lower Miocene by three groups (Fohsella, Globorotalia zealandica lineage, and G. praescitula plexus), which probably arose from separate paragloborotalid lineages. Common trends (size increase, chamber compression, keel development, reduced wall relief) early in the radiation culminated in the evolution of disk¬ like taxa which, since the middle Miocene, have been centered in the tropics. The later phase of the radiation (post middle Miocene) was marked by architectural diversification as spiroconical (e.g., G. margaritae), ventroconical (e.g., G. truncatulinoides), and globose (e.g., G. inflata) taxa arose. Architec¬ tural diversification may be linked with watermass differentiation in the late Neogene. Neogene designs have close counterparts in the earlier, but phyletically isolated, Paleogene and Cretaceous radiations. There are also resemblances in ontogenetic strategies and lineage histories. Common adaptations are suggested, but specific functional explanations have not been established. Periods of major redesign are recognized in most lineages and are not confined to speciation events. Examples of stasis in adult morphology occur particularly in taxa that have evolved compressed, keeled shells. Bifurcations in lineages are indistinctly represented by wide spectra of morphotypes. Within the radiation very rapid speciation events are conspicuously absent, although they possibly occurred at the origin of some lineages. The distinctly sluggish tempo of change may be due to large population sizes and their degree of intercommunication. Good examples of allopatric and parapatric speciation were not found, but the prevalence of polytypic taxa, often distributed in contiguous populations showing clinal variation, would favor the inception of parapatric speciation. Official publication date is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. Series cover design: Thetrilobite Phacops rana Green. Library of Congress Cataloging in Publication Data Cifelli, Richard. Stratigraphic record of the Neogene Globorotalid radiation (Planktonic foraminiferida).

Integrated stratigraphy of the lower Altonian (Early Miocene) sequence at Tangakaka Stream, East Cape, New Zealand

“…11 A, angiensis, Notorotalia wilsoni, Mucronina subtetragona, C), weakly convex spiral surfaces of late-formed chambers, Rectuvigerina ruatoria, and Textularia miozea. Rectoand the relatively compressed axial profile of the shell bolivina maoria appears in the upper Altonian Globorotalia (Cifelli & Scott 1986 (Fig. 11) results.…”

“…12A-H) RECOGNITION: Walters ( 1965) considered that the species evolved from Globorotalia incognita, an interpretation that has been adopted in several subsequent stratigraphic studies (reviewed by Cifelli & Scott 1986), and also shown in a cladistic analysis of some Neogene Globorotalia (Norris et al 1994). Scott et al (1990) suggested that the pattern of transformation was step-like, with architectural modifications occurring in a short stratigraphic interval.…”

“…** *** * **** *********** Vulvulina pennatula ******* ** ****** ***** * BIOSTRATIGRAPHIC UTILITY: Scott (1972) considered that the FAD indicated superior proximity to the Otaian/Altonian boundary and noted that it occurred closely above this boundary, as judged by an evolutionary bioseries in Haeuslerella (see previous section) in neritic sequences in southeastern South Island. The global dispersal of Globorotalia praescitula in neritic through oceanic water masses (Cifelli & Scott 1986) favours its use in biostratigraphy, as does its distinctive morphology. Important demerits are the small size of early individuals and their rarity.…”

Revision of the boundary between Lillburnian and Waiauan Stages (middle Miocene, New Zealand)

“…Highest occurrence of Fohsella peripheroronda Blow & Banner PHYLETIC STATUS: An early member (Blow & Banner 1966) of the F ohsella lineage which apparently persisted in the South Pacific temperate region after the demise of low-latitude populations (Cifelli & Scott 1986). The highest occurrence is interpreted as an extinction event.…”

“…Highest occurrence of Globorotalia conica Jenkins PHYLETIC STATUS: The species has been reported mainly from the Australasian region; its origin is poorly known. Cifelli & Scott (1986) regarded it as the end member of the Globorotalia zealandica lineage. There are no descendants known and the highest occurrence is considered to represent its extinction, at least in the temperate province.…”