Jurassic nannofossil research has progressed to the point where more detailed work is necessary. Existing biostratigraphic problems and initial paleogeographic inquiries cannot be addressed until taxonomic concepts have stabilized and stratigraphic distributions are better understood and correlated to a regional standard. / Most of what is known has come from study of the French and English Jurassic. This is a study of the taxonomy and stratigraphy of Portuguese Jurassic nannofossils. It is the most comprehensive and detailed investigation of its kind on this period to date and is intended to serve as a reference for comparison with other Jurassic localities. Portugal offers an excellent opportunity for such a study because several long, nearly continuous outcrops of Jurassic strata have been described, dated by ammonites and are largely represented by lithologies containing nannofossils. The nine sections studied provide stratigraphic coverage for each interval at two or more localities. Thus, a reproducible nannofossil zonation has been developed for the Portuguese Lower and Middle Jurassic (upper Sinemurian-middle Callovian) and correlated to the ammonite stratigraphy. Upper Jurassic nannofossils were recovered only from the uppermost Oxfordian-lowermost Kimmeridgian. This short interval contains the oldest known representatives of the genera Eiffellithus, Micrantholithus, Microstaurus, and Tubodiscus. Periods of dramatic assemblage turnover in the nannofossils have been identified in the Pliensbachian and Bajocian. / Considerable effort has been made to clarify taxonomic concepts. Synonymies and/or descriptions are accompanied by photomicrographs for all of the taxa recognized in the Portuguese Jurassic. One family, four genera, thirty-six species, one variety, and ten combinations are proposed as new. The following taxa are described: Axopodorhabdus adamanteus, Trapezapheles algarvensis, Pseliosphaera attenuata, Crepidolithus bajocianus, Cretarhabdus cathetus, Calcivascularis cassidyi, Luterilithus clathratus, Polypodorhabdus cordatus, Palaeopontosphaera cymbalum, Crucirhabdus decussatus, Crepidolithus dogger, Similiscutum gradsteinii, Ethmorhabdus grunii, Stephanolithion hexum var. stephanum, Pseliosphaera hillii, Similiscutum ibex, Eiffellithus inornatus, Calyculus katatonus, Incerniculum knuettelii, Vekshinella lumina, Crepidolithus lusitanicus, Stephanolithion mondegoensis, Discorhabdus noeliae, Triscutum patera, Luterilithus pavimentum, Incerniculum pectinatum, Hexapodorhabdus piperatus, Vekshinella rhombocentrum, Discorhabdus sagresensis, Triscutum skaphos, Crepidolithus sulcus, Triscutum sullivanii, Parhabdolithus tentopons, Incerniculum torquatum, Crucirhabdus trunculocavus, Tubodiscus ufo, Zeugrhabdotus vitreus, and Annulithus vulcanus. / Source: Dissertation Abstracts International, Volume: 49-03, Section: B, page: 0678. / Major Professor: Sherwood W. Wise. / Thesis (Ph.D.)--The Florida State University, 1987.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76245 |
| Contributors | Bergen, James Alan., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 583 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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