Link between complex internal structures and stratigraphy: Xradia – ZEISS MicroXCT-400 of genus Sphaerogypsina Galloway 1933

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Ber. Inst. Erdwiss. K.-F.-Univ. Graz ISSN 1608-8166 Band 21 Graz 2015
STRATI 2015 Graz, 19 – 23 July 2015
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Link between complex internal structures and stratigraphy:
Xradia – ZEISS MicroXCT-400 of genus Sphaerogypsina Galloway 1933
DROBNE, Katica1, ĆOSOVIĆ, Vlasta2, HOHENEGGER, Johann3, ČRETNIK, Janko4,
BAUMGARTNER-MORA, Claudia5, ROBINSON, Edward6, RÖGL, Fred7,
FERRÁNDEZ CAÑADELL, Carles8, ZUSCHN, Martin3, DOLENEC, Tadej9
1 I. Rakovec Institute of Paleontology, Scientific Research Center SAZU, Ljubljana, Slovenia, email:
katica.drobne@zrc-sazu.si
2 Dept. of Geology, Faculty of Science, University of Zagreb, Zagreb, Croatia
3 Dept. of Paleontology, University of Vienna, Geozentrum, Austria
4 Slovenian National Building and Civil Engineering Institute, Ljubljana, Slovenia
5 Institute of Earth Sciences, University of Lausanne, Switzerland
6 Dept. of Earth & Environment, Florida International University, University Park, Miami, USA
7 Naturhistorisches Museum Wien, Vienna, Austria
8 Dept. Estratigrafia, Paleontologia I Geociencies Marines, Facultat de Geologia, University of Barcelona, Spain
9 Dept. of Geology, Faculty of Natural Sciences and Engineering, University of Ljubljana, Slovenia
First, spherical to semi-spherical forms, ranging in diameter from 0.6 to 2 mm with a characteristic
chess-board surface and common in Paleogene tropical shallow-water carbonates were described as
bryozoans. Later, such forms were classified into the foraminiferal species Sphaerogypsina globulus.
In a number of studies that followed, morphological variations of tests found in recent sediments and
in rocks of different ages were reported (i.e. Miocene, Late Eocene and Recent). But, all globular
gypsinids have been called S. globulus sensu lato because without detailed internal structural
characterization, species identification of larger foraminifera is impossible. Without adequate test
sections, making a link between Sphaerogypsina and stratigraphy was hampered, too. To obtain an
oriented test section for the identification of Sphaerogypsina, which grows by adding chambers in
alternated cycles, is difficult. Application of Xradia – ZEISS MicroXCT-400 on tests ranging from the
Late Eocene (Hungary), Miocene (Austria) and Pliocene (Jamaica) to recent (Adriatic Sea, Red Sea
and Atlantic) combined with studies of Middle Eocene (Jamaica, Venezuela) specimens performed by
cathodoluminiscence and transmitted light microscope, document the complexity of test growth.
Resolution on a micrometric scale displays the inner character such as the size and position of the
embryonic chambers, size and shape of embryonic chambers, juvenile, adult and gerontic chamberlets,
size of pores and radial stacked superimposed chamberlets. A biometric analysis of form reveals that:
a) recent forms are smaller than fossil ones (Eocene A-forms attained up to 1.85 mm in diameter,
Miocene 1.1 mm, recent ones vary from 0.56 to 0.9 mm); b) diameters of embryonic cycles have more
or less constant values (Eocene of 0.21 mm, Miocene 0.21 mm and recent 0.19 to 0.28 mm); c)
Miocene and Red Sea tests have the same values of protoconch and deuteroconch diameters, the
Eocene test had the largest and the Adriatic form the smallest values; d) the number of inserted radial
stacks, varies according to the diameters of adult cycles. The position of embryonic apparatus
wanders, from being at the centre to way off centre (with a different transition off centre). This study
proved that differences in internal structures between the examined specimens ranging in age from
Eocene, Neogene to Recent are of taxonomic importance and therefore fall within forms known as S.
globulus more than one species exist (different genera are not excluded, however).

Berichte des Institutes für Erdwissenschaften
Karl-Franzens-Universität Graz
Band 21
Abstracts
STRATI 2015
2 International Congress on Stratigraphy
nd
19. - 23. July 2015, Graz, Austria

Editorial: Elisabeth Gülli, Werner E. Piller
Instute of Earth Sciences, Department of Geology and Palaeontology,
University of Graz, Heinrichstrasse 26, 8010 Graz, Austria
Copyright © 2015 by Instute of Earth Sciences, Department of Geology and Palaeontology,
University of Graz, Heinrichstrasse 26, 8010 Graz, Austria
ISSN 1608‐8166
Organi ing Commi eez
Execuve members
Werner E. Piller, Syvain Richoz, Georg Stegmüller, Gerald Auer, Angela Garcia‐Gallardo
University of Graz
Gerald Auer, Gertraud Bauer, Angela Garcia‐Gallardo, Elisabeth Gülli, Bernhard Hubmann,
Walter Kurz, Werner E. Piller, Claudia Puschenjak, Sylvain Richoz, Georg Stegmüller
Universalmuseum Joanneum, Graz
Bernd Moser, Ingomar Fritz, Marn Gross
Geological Survey of Austria, Vienna
Ralf Schuster, Jürgen M. Reitner
University of Vienna
Michael Wagreich
University of Natural Resources and Life Sciences, Vienna
Markus Fiebig