High spatial resolution Sr isotope and trace element record of dental enamel mineralization in a woolly mammoth tooth: Implications for paleoecological reconstructions

The Distribution and Biogenic Origins of Zinc in the Mineralised Tooth Tissues of Modern and Fossil Hominoids: Implications for Life History, Diet and Taphonomy

“…It follows that the fluctuations in Zn intensity (concentration) in prenatal dentine, dentine and secondary dentine observed in this study appear to run counter to previous findings on enamel that have concluded that variation in Zn concentration does not seem to be directly related to dietary intake [46]. Future studies that are able to track both shifts in Zn concentration in dentine alongside other isotopic evidence for seasonality [89][90][91] and dietary shifts [32] throughout tooth formation in hominoids may shed light on whether or not, for example, seasonal and/or dietary changes underlie the kind of incremental Zn fluctuations observed in this study.…”

“…Bourgon et al [32] have previously noted that Zn in the outer enamel of fossils distributes in the way it does in modern teeth and appears also to preserve its original isotopic composition. Anczkiewicz et al [90] have also shown this to be true for 87 Sr/ 86 Sr and for a number of other trace elements including Zn in more recent Upper Paleolithic mammoth enamel, all of which fluctuate seasonally. Even though Weber et al [61] have demonstrated that the outer 200-300 µm of enamel is susceptible to changes in isotopic composition, the deeper enamel may not be [90].…”

“…Anczkiewicz et al [90] have also shown this to be true for 87 Sr/ 86 Sr and for a number of other trace elements including Zn in more recent Upper Paleolithic mammoth enamel, all of which fluctuate seasonally. Even though Weber et al [61] have demonstrated that the outer 200-300 µm of enamel is susceptible to changes in isotopic composition, the deeper enamel may not be [90]. In this respect, the Zn 2+ ion in enamel may resemble the F − ion, where changes to fluoride levels in the water during enamel formation (from 0.2-6 ppm) have a considerable effect on surface enamel concentrations in fully formed teeth that increase from 1500 to 5000 ppm, but do not change the overall pattern of F 2 distribution through enamel [109].…”

“…Both dust and soil ingestion have previously been suggested as a source of trace elements in teeth [92][93][94][95]. Moreover, in mammoth teeth, where the enamel plates take many years to form, there is clear evidence of a seasonal fluctuation in Zn concentration, especially in inner enamel towards the cervix of the long enamel plates [90].…”

“…As with fluoride incorporation into enamel [37,99], as well as Mg and carbonate content [100], the distribution of Zn in enamel may reflect the composition of mineral formed both during the earlier secretory phase and during the late maturational phase via paracellular ion diffusion between smooth-ended maturational ameloblasts [15]. The assumption, however, that any change in ion concentration to higher or lower levels along an isochronous-accentuated line passing from the EDJ to the OES is always indicative of an enamel maturational effect, independent of the secretory phase ameloblasts, may not hold true for all elements [90], given the complex resorptive and ion transport functions of secretory ameloblasts [47].…”