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The AAPG/Datapages Combined Publications Database

GCAGS Transactions

Abstract


Gulf Coast Association of Geological Societies Transactions
Vol. 25 (1975), Pages 350-361

Affinity of Lucianorhabdus and Species of Tetralithus in Late Cretaceous Gulf Coast Samples

Frank H. Wind (1)

ABSTRACT

Light and scanning electron microscope study of late Cretaceous nannoplankton floras from Alabama and Gulf of Mexico DSDP Leg 10 sites reveals previously unknown phylogenetic relationships between Lucianorhabdus and elliptical species of Tetralithus. Two parallel lineages have been identified; one is based on the morphological characteristics of T. ovalis; the other, based on the characteristics of T. obscurus. Both lineages include L. cayeuxi and forms referred to as L. maleformis.

Three species are placed in synonymy with L. cayeuxi: Eurhabdus liciformis Reinhardt, L. maleformis Reinhardt, and Tetralithus servator Risatti.

Detailed study of optical and surface characteristics of species of Tetralithus casts doubt on the validity of Ramsaya, Munarinus, Russellia, Multipartis, and Ottavianus, which are all species basically similar to Tetralithus named from Mississippi localities. These genera appear to be lucianorhabdids with short spines whose appearance in the light microscope is the result of slight variation in lucianorhabdid basal symmetry modified by differing modes of preservation.


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