Shell microstructure and its inheritan ce in the calcit ic helcionellid Mackinnonia
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Vendrasco, M.J.; Checa González, A.G. Shell microstructure and its inheritan ce in the calcit ic helcionellid Mackinnonia. Estonian Journal of Earth Sciences, 64(1): 99-104 (2015). [http://hdl.handle.net/10481/35706]
PatrocinadorThe work was funded by a Marie Curie Postdoctoral Fellowship (IIF 301668) from the European Commission. This research is a contributio on to IGCP Project 591.
Mackinnonia davidi from the Cambrian (Series 2) of Australia has a prismatic outer shell layer and, as newly described here, a calcitic semi-nacre inner layer. The pattern is the same as in stenothecids such as Mellopegma, providing more evidence for a strong phylogenetic signal in the shell microstructure of Cambrian molluscs. In addition, calcite now appears to have been common in helcionellids and other molluscs during the early and middle Cambrian, with many species exhibiting foliated calcite. This is surprising given the dominance of aragonite in molluscs, both modern and from post-Cambrian fossil deposits with exceptional shell microstructure preservation, including localities from the Ordovician of the Cincinnati region, USA.