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Relic aragonite from Ordovician-Silurian brachiopods: Implications for the evolution of calcification

Balthasar U, Cusack M, Faryma L, Chung P, Holmer LE, Jin J & Percival IG (2011) Relic aragonite from Ordovician-Silurian brachiopods: Implications for the evolution of calcification. Geology, 39 (10), pp. 967-970.

Understanding the influence of aragonite/calcite sea conditions on the evolution of biocalcification relies strongly on the correct interpretation of the original composition of calcareous taxa. Aragonite dissolves or inverts into calcite over geological time, and its preservation is currently unknown to predate the Pennsylvanian. Here we present direct evidence for the common occurrence of relic aragonite in Ordovician and Silurian trimerellid brachiopods, thereby extending the known range of aragonite preservation by more than 130 million years. Together with associated hypercalcifying taxa of putatively original aragonite or high-magnesium calcite composition and considerations of the temperature dependence of aragonite and calcite precipitation, our results suggest that the evolution of aragonite biomineralization might have presented an adaptive advantage in shallow marine tropical waters of calcite seas. A targeted search for Paleozoic aragonite should both resolve the original composition of consistently recrystallized taxa and enable the reassessment of the aragonite/calcite sea paradigm in a paleoenvironmental context. © 2011 Geological Society of America.

Geology: Volume 39, Issue 10

Author(s)Balthasar, Uwe; Cusack, Maggie; Faryma, L; Chung, Peter; Holmer, Lars Erik; Jin, Jisuo; Percival, Ian G
Publication date31/10/2011
Publication date online09/2011
Date accepted by journal19/05/2011
PublisherThe Geological Society of America
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