Article: Secondary changes in micro-ornamentation of some Devonian ambocoeliid brachiopods

Studies on some species of the Ambocoeliidae from the Devonian of Poland have shown that their micro-ornamentation may be completely changed by secondary factors such as weathering, which leads to the separation of initially invisible coarse-crystalline structures, known as microspines, from the primary shell layer. Thus, secondary microspinosity appears on the surface of originally smooth or radially ornamented specimens. The recognition of primary and secondary micro-ornamentation is shown to be important in taxonomic studies. Comparative studies show that the microspines in the Ambocoeliidae are probably homologous to the microspines sensu stricio in other representatives of the Spiriferida.