Calcium isotopic variability of cervid bioapatite and implications for mammalian physiology and diet

Inferring odontocete life history traits in dentine using a multiproxy approach (δ15N, δ44/42Ca and trace elements)

“…Our results contrast with those of previous studies on Ca isotopes in mammalian enamel (humans, sheep, deer, reindeer), where milk consumption during nursing implies a trophic isotope effect fractionation toward depleted values in the tissue of the consumer directly after birth followed by a subsequent 44 Ca-enrichment toward the end of the weaning process, that is, when the individual starts an adult diversified diet. 18,38,49 Odontocete milk analyzed here for Ca isotopes (À1.32‰ and À1.10‰) is slightly lower or comparable to cow milk values. 38,44 Feeding exclusively on milk during the nursing period would normally induce 44 Ca-depleted dentine values in the analyzed Tursiops individual.…”

“…In addition, other terrestrial mammals such as cervids or hippopotamids also show anomalous 44 Ca-depleted values relative to their expected trophic position, 36,37 but taking into consideration multiple Ca sources, such discrepancies can also be partly explained. 18 Here, we aim to further clarify mechanisms behind Ca isotope variability in odontocetes by using, for the first time, a spatially resolved multiproxy approach on a single individual. Also, δ 15 N values stay elevated during the first year after birth, indicating that the young is nursed on mother milk during its first year, that is, feeding on a trophic level higher than its mother.…”

“…Despite challenging analytical procedures using multicollector inductively coupled plasma mass spectrometry (MC-ICPMS), [32][33][34] Ca isotopes are becoming available to study dietary preferences among modern and fossil mammals, although physiological processes behind fractionation need to be constrained. 7,18,[35][36][37][38][39][40] Calcium-normalized strontium (Sr), barium (Ba), zinc (Zn) and magnesium (Mg) ratios are increasingly measured using laser ablation, yet their significance for monitoring metabolism and diet are under discussion. [19][20][21][22][23][24] Not only do these geochemical proxies offer a fine spatial resolution in incremented tissues, but they would also benefit from a confrontation with N isotope data.…”

“…[9][10][11] Because the community that introduced the use of stable isotope analyses was in large part driven by archeological questions, 12 it is no surprise that tooth enamel was for a long time, and still is, elected as the tissue of choice due to its compactness and durability, preserving information from past contexts. [13][14][15] Nonetheless, a number of limitations have stimulated discussions such as how the recording of elements and their isotopes during enamel secretion and maturation processes is representative of isotopic compositions [16][17][18] or trace element contents. [19][20][21][22][23][24] Another important limitation is that in most mammals, teeth become replaced once (diphyodonty) and the entire enamel crown does not capture a continuous record from birth to death but is limited to a time range encompassing several months to a couple of years.…”

Exploring diet shifts and ecology in modern sharks using calcium isotopes and trace metal records of their teeth

“…This is estimated to result from the partition of lighter against heavier isotopes from the feeding bowl (or dietary source) during physiological assimilation of the Ca (e.g., during bone mineralization and/or urine excretion). Current knowledge on the physiological processes behind Ca isotopic fractionation is limited to experiments and box models conducted on mammals (e.g., Morgan et al, 2012;Eisenhauer et al, 2019;Tacail et al, 2020;Hassler et al, 2021), while no experimental studies on elasmobranchs have been published yet. Nevertheless, teeth from elasmobranchs with filter-feeding behaviours have the highest δ 44/42 Ca values ($ À0.1 to À0.3‰) (Akhtar et al, 2020;Martin et al, 2015;Skulan & DePaolo, 1999), whereas top predators ingesting the mineralized tissue of smaller predators (by swallowing other elasmobranchs and/or bony fishes) have the lowest δ 44/42 Ca values ($ À0.7 to À1‰).…”