EAR-PF: A multidisciplinary investigation of biotic and environmental change within the Triassic-Jurassic strata of southwestern Honshu, Japan

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Dr. Benjamin T. Breeden III has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out research on the beginning of the Age of Reptiles in Japan under the mentorship of Dr. Makoto Manabe at the National Museum of Nature and Science. The “Age of Reptiles,” or Mesozoic Era, is the interval of geologic time spanning the Triassic, Jurassic, and Cretaceous periods (~252–66 million years ago) during which reptiles such as non-avian dinosaurs (i.e., dinosaurs other than birds) dominated terrestrial ecosystems. Throughout the early Mesozoic, life on Earth endured and recovered from two mass extinctions tied to global environmental change, resulting in the evolution and diversification of many groups of vertebrate animals that remain important components of modern ecosystems. The early Mesozoic vertebrate fossil record has received heavy scientific scrutiny in recent decades; however, vertebrate fossil-bearing strata from the Late Triassic and Early Jurassic epochs in Japan have remained widely overlooked by researchers outside of Japan despite over a century of research by Japanese researchers. This project will focus on Triassic-Jurassic strata in southwestern Honshu (the largest of the main Japanese islands) and integrate observations of vertebrate fossils from Japanese museum collections, field geological and paleontological observations, laboratory geochemical analyses, and the translation of Japanese scientific literature into English to elucidate the relationship between vertebrate evolution and environmental change along the northeastern margin of the supercontinent Pangea, where this region of Japan was positioned throughout the early Mesozoic. This project will facilitate outreach and education via public lectures, undergraduate mentoring, and museum exhibit design; and it will make certain research on early Mesozoic geology and paleontology in Japan accessible to a broader English-speaking audience for the first time via publications for both scientific and general readers.The established early Mesozoic vertebrate fossil record of Japan is sparse but diverse, and many vertebrate fossil-bearing early Mesozoic strata in Japan lack precise and accurate multiproxy datasets with which to evaluate hypotheses regarding paleobiogeography and environmentally driven biotic change. These strata are therefore relatively untapped potential resources for studying these changes. Among the most productive vertebrate fossil-bearing early Mesozoic strata in Japan are the Upper Triassic Mine Group, and the Lower-Middle Jurassic Toyora and Kuruma groups, all of which crop out across regions in southwestern Honshu. This project will establish an integrated record of environmental change and vertebrate evolution in northeastern Pangea throughout the early Mesozoic via paleontological and geological reconnaissance of these strata and a revision of the existing early Mesozoic vertebrate fossil records from these and other Triassic and Jurassic strata in museum collections across Japan. Phylogenetic and biogeographic methods will be used to evaluate the anatomy and evolutionary history of the vertebrate fossils from these strata, and the carbon isotope chemostratigraphy of these strata will be established for correlation of major carbon isotope perturbations associated with relevant environmental crises (e.g., Carnian Pluvial Event; Toarcian Ocean Anoxic Event). This work will contribute to the broader knowledge of environmental and biotic change throughout the early Mesozoic at regional and global scales.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.