Teeth recovered from a beloved zoo elephant that died in 2008 are helping University of Utah geologists develop a method for tracking the movements of large herbivores across landscapes, even for animals now extinct, such as mastodons and mammoths.
Outlined in recently published findings, the technique analyzes isotope ratios of the element strontium (Sr), which accumulates in tooth enamel. For large plant-eating land mammals, the relative abundance of two strontium isotopes in teeth and tusks reflects where the creature may have roamed during its lifetime.
“Our study not only adds to our understanding of how tooth enamel records an animal’s Sr isotope exposure, but also helps to reconstruct animal migrations from Sr isotope analysis,” lead author Deming Yang said in a posting about the research. “It can be applied to studies of paleobiology, to answer how megaherbivores migrated in the past. It can also be applied to studies of modern conservation and forensics, to trace the origins of illegal ivory trade and other forms of wildlife trafficking.”
The star of the study is Misha, a female elephant acquired by Salt Lake City’s Hogle Zoo in 2005.
Chemically similar to calcium, strontium from the environment accumulates in highly mineralized tissues, such as animals’ bones and teeth.
“As animals eat and drink, they pick up this environmental signature and store it in their teeth, preserving a series of environmental exposures like historic archives,” Yang wrote. This is because the geology of different places presents different isotope signatures for 87-strontium/86-strontium [87Sr/86Sr] and those isotope ratios are reflected in plants and water.
“We use other elements, but in this case, we’re focusing on strontium, which has proven to be really useful because of its strong link to geology,” coauthor Gabe Bowen said. “Ultimately it comes down to where that element comes from, how the animal gets it into their body and from what sources.”
The isotope 87Sr is radiogenic, meaning it is produced from the decay of another element, in this case rubidium, found next door to strontium on the Periodic Table, whose half-life exceeds 49 billion years, about 10 times the age of Earth. While 87Sr increases over time, the abundance of other strontium isotopes remains fixed. Accordingly, isotope ratios are a proxy for the age of rocks and typically differ from place to place.
Coauthor Thure Cerling, a highly decorated distinguished U professor of both geology and biology, is a pioneer in the use of isotope analysis to shed light on ecological questions such as soil formation, animal physiology, wildlife ecology and climate change.
Read the entire story by Brian Maffly in @TheU.