Stable Isotopic Analysis of Equid (Horse) Teeth from Mongolia
This study examines the carbon and oxygen isotopic composition of bioapatite in equid tooth enamel as a potential record of environmental change in a north-central Mongolian sampling area between 51.4°N, 99.0°E and 44.6°N, 106.9°E (northwest to southeast). Mammal tooth enamel is useful as a palaeoclimate proxy because it is a durable material that directly reflects the isotopic composition of the body, and therefore organism diet and water intake. In addition, tooth enamel accumulates sequentially from crown to root over the period of months to years and often records seasonal variation. Thus, the inter- and intra-tooth variations in the stable carbon (ä13C) and oxygen (ä18O) isotopic composition of horse tooth enamel may provide a high-resolution record about climatic factors such as temperature and moisture availability as well as the composition and availability of forage during the tooth growth period. Sequential incremental samples from modern horses were analyzed to provide a record of the carbon and oxygen isotopic values preserved during tooth enamel formation and mineralization. To constrain the final composition of the bioapatite, modern enamel stable isotopic compositions were compared with the compositions of meteoric waters and plants from comparable localities. Modern teeth displayed a marked regional seasonal oscillation in ä18O and record a latitudinal shift observed in the ä18O of meteoric waters. In addition, bulk and sequentially sampled profiles from the modern teeth were used as a comparative set with samples from archaeological teeth (Bronze Age, ca. 1000 B.C.) and suggest that climatic patterns were roughly equivalent during both periods, with a similar plant communities, and similar summer precipitation/temperature patterns. However, seasonality may have been more intense in Bronze Age ca. 1000 B.C., with similar summer highs but more severe winters. The difference could be due to This work contributes to ongoing research into the climatic history of Central Asia and to the application of equid tooth enamel as an environmental proxy in this region.
Advisor:Michael Rosenmeier; Daniel Bain; Charles Jones; Francis Allard
School:University of Pittsburgh
School Location:USA - Pennsylvania
Source Type:Master's Thesis
Date of Publication:05/18/2009