Chapter 4: WALL TEXTURES OF EOCENE PLANKTONIC FORAMINIFERA
Published:August 31, 2006
Christoph Hemleben, Richard K. Olsson, 2006. "WALL TEXTURES OF EOCENE PLANKTONIC FORAMINIFERA", Atlas of Eocene Planktonic Foraminifera, Paul N. Pearson, Richard K. Olsson, Brian T. Huber, Christoph Hemleben, William A. Berggren
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Analysis of the wall structures of Eocene normal perforate planktonic foraminifera permits the separation of groups of taxa that have significance for phylogeny and classification. The following spinose wall textures are recognized: sacculifer-type, ruber-type, sacculifer/ruber-type, Turborotalita-type, bulloides-type, and Clavigerinella-type. The Clavigerinella-type is subdivided into a Hantkenina-subtype in which spines have apparently been lost, except perhaps in some juvenile stages. Nonspinose wall texture includes smooth-walled, muricate, Globoquadrina-type, Turborotalia-type, and microperforate. The Globoquadrina-type is believed to have originated from the muricate genus Acarinina in the development of Dentoglobigerina, and the Turborotalia-type originated from the smooth-walled genus Globanomalina in the development of the genus Turborotalia. Diagenetic alterations of primary wall texture include dissolution, degradation of layered wall structure, and recrystallization. This has implications for the recognition/interpretation of wall texture.
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Atlas of Eocene Planktonic Foraminifera
The biostratigraphy, taxonomy and phylogenetic systematics of Eocene planktonic foraminifera are treated in an illustrated atlas format. Scanning electron micrographs of the type specimens of 114 species are illustrated for the first time, providing new insight to the shell architecture and wall texture, particularly for species that were poorly illustrated when first described. The phylogenetic relationships of all species of Eocene planktonic foraminifera are reviewed. Analysis of wall textures, based on well-preserved material (much of which is illustrated for the first time) provides the basis for the higher taxonomy. Accordingly, Eocene normal perforate planktonic foraminifera are divided into the Families Globigerinidae, Hantkeninidae, Truncorotaloididae, Globoquadrinidae and Hedbergellidae. Eocene microperforate species, which are less well known, are placed in the Families Guembelitriidae, Chiloguembelinidae, Hetero-helicidae, and Cassigerinellidae.
The biostratigraphic occurrences of all species of Eocene planktonic foraminifera are reviewed. Recently proposed modifications to the standard (sub)tropical and Antarctic zonations (the so-called “E-zones” of Berggren and Pearson, 2005 and “AP-zones” of Huber and Quillévéré, 2005) are followed in this atlas.
One hundred and sixty-eight species of Eocene planktonic foraminifera are recognized, including 5 species of Catapsydrax, 2 species of Globorotaloides, 1 species of Guembelitrioides, 2 species of Paragloborotalia, 6 species of Parasubbotina, 1 species of Pseudoglobigerinella Olsson and Pearson n. gen., 1 species of Globigerina, 5 species of Globoturborotalita, 15 species of Subbotina, 2 species of Turborotalita, 11 species of Globigerinatheka, 1 species of Orbulinoides, 5 species of Clavigerinella, 1 species of Cribrohantkenina, 10 species of Hantkenina, 28 species of Acarinina, 4 species of Morozovelloides Pearson and Berggren n. gen., 16 species of Morozovella, 1 species of Astrorotalia, 4 species of Igorina, 2 species of Planorotalites, 1 species questionably assigned to Praemurica, 3 species of Dentoglobigerina, 5 species of Globanomalina, 1 species of Planoglobanomalina Olsson and Hemleben n. gen., 4 species of Pseudohastigerina, 9 species of Turborotalia, 6 species of Chiloguembelina, 1 species of Streptochilus, 4 species of Tenuitella, 2 species of Cassigerinella, 1 species of Cassigerinelloita, 2 species of Jenkinsina, 4 species of Zeauvigerina, and 2 species of Dipsidripella.
The following taxa are named for the first time; the genera Pseudoglobigerinella (Olsson and Pearson n. gen.; type species Globigerina wilsoni bolivariana Petters), Morozovelloides (Pearson and Berggren n. gen.; type species Globorotalia lehneri Cushman and Jarvis), Planoglobanomalina (Olsson and Hemleben n. gen.; type species Planoglobanomalina pseudoalgeriana Olsson and Hemleben n. sp.); and the species Parasubbotina pseudowilsoni Olsson and Pearson n. sp., Paragloborotalia griffinoides Olsson and Pearson n. sp., Globorotaloides eovariablis Huber and Pearson n. sp., Globorotaloides quadrocameratus Olsson, Pearson and Huber n. sp., Globoturborotalita bassriverensis Olsson and Hemleben n. sp., Turborotalita praequinqueloba Olsson and Hemleben n. sp., Hantkenina singanoae Pearson and Coxall n. sp., Acarinina mcgowrani Wade and Pearson n. sp., Acarinina pseudosubsphaerica Berggren and Pearson n. sp., and Planoglobanomalina pseudoalgeriana Olsson and Hemleben n. sp.