Current IF 1.175
Latest issue (RSS 2.0)
Contact Editorial Office at
Bulletin of Geosciences
Published by ©
Czech Geological Survey,
W. Bohemia Museum Pilsen
ISSN: 1802-8225 (online),
Palaeogeographical patterns in Late Ordovician bryozoan morphology as proxies for temperature
Published in: Bulletin of Geosciences, volume 88, issue 2; pages: 417 - 426; Received 20 November 2012; Accepted in revised form 21 February 2013; Online 31 May 2013
Keywords: bryozoans, cosmopolitan genera, latitudinal adaptations, univariate and multivariate statistical analysis,
A list of samples, localities and institutions where the samples are stored
AbstractSeveral studies have revealed temperature-related patterns in recent bryozoans, both in the chemical composition of the skeleton and in the morphological characters of the colonies, but comparable studies on Palaeozoic bryozoans are lacking. In this paper a statistical analysis of the morphological differences is undertaken between congeneric species of some Ordovician bryozoans from warm- and cold-water settings. For this study ten eurythermic cosmopolitan bryozoan genera from the Upper Ordovician were selected from the Mediterranean, Avalonia, Baltic and Laurentia-Siberian provinces. These genera are: Ceramopora and Ceramoporella (Cystoporata); Diplotrypa, Eridotrypa, Hallopora, Heterotrypa, Monticulipora and Trematopora (Trepostomata); Graptodictya (Cryptostomata); and Kukersella (Cyclostomata). The study involved 154 samples belonging to 104 different species. Twenty-eight morphological characters were measured, although only 21 were used in the final statistical analysis. Univariate (t, F, Kolmogorov-Smirnov and Mann-Whitney tests), multivariate discriminant and multivariate ordination (Principal Coordinates, Principal Components, Correspondence, and Detrended Correspondence) analyses were performed on the data. For the univariate and multivariate discriminant analyses, the total set of samples was divided a priori into cold- and warm-water subsets based on palaeolatitude: samples from the Mediterranean province were attributed to the cold-water subset, whereas samples from Avalonia, Baltic and the Laurentian-Siberian provinces were included in the warm-water subset. For the multivariate ordination analysis no a priori grouping by water temperature was imposed, and the aim of these analyses was to test whether different samples were correctly arranged along a water temperature gradient. The univariate statistical analysis showed that there are clear morphological differences between cold- and warm-water species in six of the ten Late Ordovician bryozoan genera analysed in this study, although these differences are only evident for some of the characters used, and only when the analysis is performed on individual genera. The best characters to differentiate species by water temperature are those related to the size of the zooidal polymorphs, especially the diameters of the autozooecia, mesozooecia and exilazooecia. With the exception of one genus (Trematopora), cold-water species have larger zooids. The discriminant analysis was able to classify correctly as warm- or cold-water 100% of the samples for two genera, slightly below 95% for two other genera, and between 67% and 90% for the remaining six genera. Finally, the multivariate ordination analysis was able to separate species by palaeogeographical province in some genera, but these provinces were not correctly arranged along a palaeolatitudinal gradient using any of the methods used.
Bassler, R.S. 1911. The early Paleozoic Bryozoa of the Baltic provinces. United States National Museum Bulletin 77, 1-382.
Buttler, C.J. 1991. A new upper Ordovician bryozoan fauna from the Slade and Redhill Beds, South Wales. Palaeontology 34, 77-108.
Cocks, L.R.M. & Torsvik, T.H. 2006. European geography in a global context from the Vendianto the end of the Palaeozoic. Journal of the Geological Society of London 32, 83-95.
Conti, S. 1990. Upper Ordovician Bryozoa from Sardinia. Palaeontographia Italica 77, 85-165.
Ernst, A. & Key, M. 2007. Upper Ordovician Bryozoa from the Montagne de Noire, Southern France. Journal of Systematic Palaeontology 5, 359-428.
Fortey, R.A. & Cocks, L.R.M. 2003. Palaeontological evidence bearing on global Ordovician-Silurian continental reconstructions. Earth-Science Reviews 61, 245-307.
Fortey, R.A. & Cocks, L.R.M. 2005. Late Ordovician global warming - the Boda event. Geology 33, 405-408.
Hammer, O., Harper, D.A.T. & Ryan, P.D. 2008. PAST v 2.15. Paleontological Statistics Software: Package for Education and Data analysis.
Hughes, D.J. & Jackson, J.B.C. 1990. Do constant environments promote complexity of form?: The distribution of bryozoan polymorphism as a test of hypotheses. Evolution 44, 889-905.
Jiménez-Sánchez, A. 2009. The upper Katian (Ordovician) bryozoans from the Eastern Iberian Chains (NE Spain). Bulletin of Geosciences 84, 687-738.
Jiménez-Sánchez, A. 2010. New Monticuliporidae (Trepostomata) from the Cystoid Limestone Formation (Upper Ordovician) of the Iberian Chains (NE Spain). Geodiversitas 32(2), 177-199.
Jiménez-Sánchez, A. & Villas, E. 2010. The bryozoan dispersion into the Mediterranean margin of Gondwana during the pre-glacial Late Ordovician. Palaeogeography, Palaeoclimatology, Palaeoecology 294, 220-231.
Kuklinski, P. & Taylor, P.D. 2008. Are bryozoans adapted for living in the Arctic? Virginia Museum of Natural History, Special Publication 15, 101-110.
Loxton, J., Kuklinski, P., Mair, J.M., Jones,M.S. & Porter, J.S. 2012. Patterns of magnesium-calcite distribution in the skeleton of some polar bryozoan species, 169-185. In Ernst, A., Schäfer, P. & Scholz, J. (eds) Bryozoan Studies. Springer, Heidelberg.
Maw, U.B., San, U.B. Ross, J.R.P. & Ciochon, R.L. 1976. The Ordovician bryozoan (Ectoproct) Diplotrypa from Central Burma. Geological Magazine 113, 515-518.
Okamura, B., O’Dea, A. & Knowles, T. 2011. Bryozoan growth and environmental reconstruction by zooid size variation. Marine Ecology Progress Series 430, 133-146.
Schäfer, P. & Bader, B. 2008. Geochemical composition and variability in the skeleton of the bryozoan Cellaria sinuosa (Hassall): biological versus environmental control. Virginia Museum of Natural History, Special Publication 15, 269-278.
Schlager, W. 2005. Carbonate sedimentology and sequence stratigraphy. 200 pp. SEPM, Tulsa.
Smith, A.M., Key, M.M. Jr. & Gordon, D.P. 2006. Skeletal mineralogy of bryozoans: taxonomic and temporal patterns. Earth-Science Reviews 78, 287-306.
Taylor, P.D. & Allison, P.A. 1998. Bryozoan carbonates through time and space. Geology 26, 459-462.
Taylor, P.D., James, N.P., Bone, Y., Kuklinski, P. & Kyser, T.K. 2009. Evolving mineralogy of cheilostome bryozoans. Palaios 24, 440-452.
Taylor, P.D. & Sendino, C. 2010. Latitudinal distribution of bryozoan-rich sediments in the Ordovician. Bulletin of Geosciences 85, 565-572.
Ulrich, E.O. 1893. On Lower Silurian Bryozoa of Minnesota. Minnesota Geology and Natural History Survey, Final Report 3(1), 96-332.