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Article: Crystallographic orientations of structural elements in skeletons of Syringoporicae (tabulate corals, Carboniferous): implications for biomineralization processes in Palaeozoic corals

Publication: Palaeontology
Volume: 58
Part: 1
Publication Date: January 2015
Page(s): 111 132
Author(s): Ismael Coronado, Alberto Pérez-Huerta and Sergio Rodríguez
Addition Information

How to Cite

CORONADO, I., PÉREZ-HUERTA, A., RODRÍGUEZ, S. 2015. Crystallographic orientations of structural elements in skeletons of Syringoporicae (tabulate corals, Carboniferous): implications for biomineralization processes in Palaeozoic corals. Palaeontology, 58, 1, 111-132.

Author Information

  • Ismael Coronado - Departamento de Paleontología, Universidad Complutense de Madrid, Madrid, Spain (email: ismael.coronado@geo.ucm.es)
  • Alberto Pérez-Huerta - Department of Geological Sciences, University of Alabama, Tuscaloosa, AL, USA (email: aphuerta@as.ua.edu)
  • Sergio Rodríguez - Instituto de Geociencias (IGEO, CSIC-UCM), Madrid, Spain (email: sergrodr@geo.ucm.es)
  • Sergio Rodríguez - Departamento de Paleontología, Universidad Complutense de Madrid, Madrid, Spain

Publication History

  • Issue published online: 7 JAN 2015
  • Article first published online: 5 SEP 2014
  • Manuscript Accepted: 15 JUL 2014
  • Manuscript Received: 6 MAY 2014

Funded By

Spanish Ministerio de Economía y Competitividad. Grant Number: CGL2012-30922BTE
Complutense University Research Group. Grant Number: 910231
FPI-UCM 2 Grant
Synthesis Grant

Online Version Hosted By

Wiley Online Library (Free Access)
Get Article: Wiley Online Library [Free Access]

Abstract

The crystallographic orientation of structural elements in skeletons of representatives of Carboniferous Syringoporicae (Auloporida) has been analysed by scanning electron microscopy (SEM), petrographic microscopy and electron backscatter diffraction (EBSD) on specimens from the Iberian Peninsula. The skeletons of the tabulate corals of the Syringoporicae consist of biogenic calcite crystals, and their microstructure is composed of lamellae, fibres and granules, or of a combination of these. Independent of the microstructure, the c-axis is oriented towards the lumen, quasi-perpendicular to the growth direction of the skeleton (perpendicular to the morphological axis lamellae, parallel to fibres). Most phaceloid taxa have a turbostratic distribution, as a biogenic response to prevent the cleavage of crystals. Cerioid and some phaceloid corals, whose microstructure is conditioned by wall elements, do not exhibit turbostratic distribution. Wall elements are determined by the biology of each taxon. Holacanth septal spines are composed of fibres arranged in a cone-shape structure, sometimes clamped to the external part of the corallite and show a complex crystallography. Monacanth septal spines are spindle shaped and composed of bundles of fibres. Tabulae are composed of lamellae. Their development and crystallographic orientation depends on the position of the epithelium in each case. Shared walls are formed by a combination of the walls of two independent corallites with a median lamina, composed of granules; these have a crystallographic orientation between that of the two corallites. The growth of the microstructure is derived by a coordinated stepping mode of growth, similar to other groups of organisms such as molluscs and scleractinians. The nucleation and formation of packages of co-oriented microcrystals suggest a growth mode similar to mineral bridges with a competitive growth mode between each crystal. The growth pattern of corallites suggests that the growth direction is divided into two main components: a horizontal growth direction towards the lumen and a vertical direction towards the top.

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