PALEOENVIRONMENTAL INTERPRETATION THROUGH OXYGEN ISOTOPES IN PHOSPHATE FROM BAROSAURUS INDICATE INCREASING ARIDITY AT THE AARON SCOTT QUARRY (MORRISON FORMATION, JURASSIC PERIOD)

Taphonomic research, stratigraphy, and oxygen isotopes were used to determine the diet and climate of a Barasaurus from the Morrison Formation to determine if a change in the animal’s diet was evident during the animal’s life time. Data suggests that there was an increase in temperature and aridity over the animal’s lifetime. Oxygen isotopes of phosphate from the femur of the Barosaurus range from 13 to 16 per mil dO₁₈ from the inner-most part of the bone to the outside edge. Millimeter-scale fluctuations in the dO₁₈ of 1-2 per mil may be evidence of yearly fluctuations. The overall trend is an increase in dO₁₈. This is consistent with a diet of increasingly drought tolerant plants including seed ferns and ginkos as opposed to conifers.