The ratio of zinc isotopes in ancient animal teeth correlates with the underlying rock composition and the animal's body size, meaning these factors affect the isotope signal independently of what...
Mechanism
Synthesis from 1 study
The zinc in ancient animal teeth changes based on what the ground is made of and how big the animal was, not just what it ate. Bigger animals keep more of the heavier zinc, and rocks underground change the type of zinc plants absorb — so even if two animals ate the same food, their teeth could look...
Most probable mechanism
The zinc in animal teeth comes from what they eat, but the type of zinc isotopes changes based on the rocks in the ground they live on and how big the animal is. Bigger animals hold onto heavier zinc isotopes more than smaller ones, and if the soil has more of certain zinc types, that gets into the plants and then into the animals, changing the zinc signature in their teeth — even if they eat the same food.
Zinc in soil is absorbed by plants through root systems, with preferential uptake of heavier zinc isotopes (66Zn) due to biochemical transport mechanisms that favor lighter isotopes for translocation to leaves.
Herbivores incorporate the isotopic signature of plant tissues into their enamel during tooth mineralization, preserving the elevated 66Zn levels from their diet.
Body mass correlates with metabolic efficiency in zinc retention, where larger animals retain a greater proportion of heavier zinc isotopes due to slower turnover rates and reduced excretion of 66Zn through renal and biliary pathways.
Geological bedrock composition determines the isotopic composition of bioavailable zinc in soil, which is transferred to plants and subsequently to herbivores, creating a spatially variable baseline isotopic signature independent of diet.
Zinc isotopes in enamel bioapatite are incorporated during tooth formation and remain chemically stable after death, preserving the combined influence of dietary intake, body size, and local geology.
Evidence from Studies
Supporting (1)
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Zinc isotopes in Late Pleistocene fossil teeth from a Southeast Asian cave setting preserve paleodietary information
Contradicting (0)
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