Incremental growth and mineralogy of Pannonian (Late Miocene) sciaenid otoliths: paleoecological implications

Abstract

Ontogenetic age and body dimensions were studied on three extremely well-preserved sciaenid fish otoliths from sublittoral marls of Lake Pannon from Doba, Bakony Mts, Hungary. Macroscopic and microscopic observations offered clear evidence for the preservation of the genuine structural characteristics, for instance the bipartite incremental features. Ontogenetic ages were assigned for the three specimens as 16, 7 and 6 years by counting the annuli of the sagittae. Analytical results prove that the original aragonitic mineralogy has been preserved making them, and probably other Late Miocene teleost fossils, suitable for future microchemical analysis to reconstruct the past physicochemical environment.

Strontium speciation in archaeological otoliths

“…60,61 As a standard practice, altered otolith specimens are distinguished from unaltered ones by detection of microstructural alteration and/or change in the identity of calcium carbonate polymorph. 26 An intact microstructure is dened by the presence of growth marks typical of otoliths (daily and yearly increments), 23 long needle-like (prismatic) aragonite crystals, 26,62,63 and/or the absence of recrystallised or neoformed minerals. 7,17,18,26,62 Aragonite is metastable and will tend to transform to calcite over time.…”

“…26 An intact microstructure is dened by the presence of growth marks typical of otoliths (daily and yearly increments), 23 long needle-like (prismatic) aragonite crystals, 26,62,63 and/or the absence of recrystallised or neoformed minerals. 7,17,18,26,62 Aragonite is metastable and will tend to transform to calcite over time. 59 The absence of calcite and vaterite is considered an indicator of geochemical preservation.…”

Biogenic and diagenetic indicators in archaeological and modern otoliths: Potential and limits of high definition synchrotron micro-XRF elemental mapping

“…When performed, the identification of altered from unaltered specimens is sometimes limited to visual examination for morphological changes of the otoliths overall. Other criteria are occasionally used based on microstructural features: presence of daily and annual increments, crystal habit, and identification of CaCO 3 polymorphs (Dufour et al, 2000;Vanhove et al, 2011;Kern et al, 2012). Preservation of the microstructure and mineralogy is often taken to indicate that the geochemistry therein is pristine, but absence of morphological and mineralogical change does not guarantee a pristine geochemical signal (Dufour et al, 2000).…”

Classification of otoliths of fishes common in the Santa Barbara Basin based on morphology and chemical composition

“…To reduce potential bias due to otolith shape alteration, we included elemental composition in our analyses. Diagenetic processes have been shown to not D r a f t have significantly altered the elemental composition of fossil otoliths, when compared to modern specimens (Degens 1969;Kern 2012;Cook 2015;Cook 2016).…”