2021 Undergraduate Research Showcase


Reconstructing the Mid-Late Triassic Paleoclimate of the Paraña Basin Using Carbon Isotope Analysis of Dinosaur, Crocodilian, and Reptile Enamel

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Linda Reynard


The Triassic Period (251 – 199 Ma), best known as the dawn of the dinosaur age, remains in many ways an enigma. Two of the largest known mass extinctions, both arising from drastic changes to the global climate, mark the beginning and end of this Period. This study seeks to constrain the Triassic paleoclimate, specifically the transition from Mid to Late Triassic, through stable-isotope examination of dinosaur and reptilian dental enamel. A mass spectrometer, based in the Boise State Geoscience lab, was used to analyze twelve samples from Brazil’s fossil-rich Paraña Basin.

The analytic results, expressed in terms of their Carbon-13 to Carbon-12 isotope ratio (or δ13C), strongly suggest a significant decrease in Mean Annual Precipitation in the Paraña Basin over this 10-15 million year period. The estimated maximum decrease in MAP is roughly equivalent to the modern-day difference in annual rainfall between Boise, ID and Phoenix, AZ. This study’s results, based on stable-isotope analysis of dental enamel samples from the Triassic period, match (and validate) previous models of this paleoclimatic period in scientific literature.

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