ABSTRACT

Part I: Nontechnical Description

Flowering plants are the dominant land plant group on Earth today. They play essential roles in climate-life interactions and are fundamental for human well-being (health, food, materials). Despite their importance to us, their early evolution has remained enigmatic. Without the geological context of how these plants evolved, we will not fully understand their roles in regulating climate and structuring environments. This is important as terrestrial ecosystems today are undergoing many changes.
The fossil record indicates that critical events relating to the early diversification of flowering plants occurred during the Cretaceous period (145?66 million years ago). Recent discoveries of fossil flowers and fruits from this time period have significantly furthered our understanding of early flowering plant evolution. However, the majority of these discoveries are from the Northern Hemisphere while similar discoveries from the Southern Hemisphere are relatively lacking. This project will address this paucity of data by collecting and describing Late Cretaceous flowering plant fossils from Western Antarctica and placing them in evolutionary frameworks to better understand early flowering plant evolution, biogeographic history, and Antarctica?s role in the formation of modern ecosystems. Western Antarctica is the only place in the Southern Hemisphere that is reported to contain Late Cretaceous-aged (100?66 million years ago) three-dimensionally preserved flowers and fruits. Therefore, the recovery and study of these fossils can meaningfully further our understanding of the early phases of flowering plant evolution. This work will result in the description of new species that will be placed in evolutionary analyses and biogeographic frameworks, which will help clarify the Cretaceous diversification of flowering plants in the Southern Hemisphere. These fossils will provide insights that will allow us to anticipate which plants might thrive in a warming Antarctic and world.

Part II: Technical Description
The Late Cretaceous diversification of flowering plants (angiosperms) in the Southern Hemisphere is poorly understood due in part to the limited amount of well-characterized fossil plant reproductive structures. Paleobotanical studies indicate that Antarctica was an important area for the Cretaceous diversification of flowering plants and is the only place in the Southern Hemisphere that is known to contain permineralized Late Cretaceous-aged angiosperm reproductive structures. The proposed research will elucidate Antarctica?s role in the evolution of angiosperms and assembly of modern ecosystems by recovering and characterizing Late Cretaceous Antarctic angiosperms, placing them within a phylogenetic context, and testing for biogeographic links between North America and Gondwana as has been observed for animals. Fieldwork will be conducted in the James Ross Basin of West Antarctica where previous reports and preliminary data indicate the presence of Late Cretaceous-aged floras that include structurally preserved reproductive structures. The exceptional preservation of these fossils allows us to record data essential for placing them in a phylogenetic framework from which their evolutionary and biogeographical context can be determined. The taxonomically informative and well-preserved angiosperm reproductive structures within the James Ross Basin are of a crucial age and from an important geographic area for understanding the phylogenetic diversification of Southern Hemisphere angiosperms and ecosystems. Collected fossils will be examined using standard physical techniques and microCT imaging. The study of these fossils will result in the description of new species and possibly higher taxa and provide a unique perspective into the floral diversity and composition of West Antarctica during the Cretaceous. In addition, the fossils will be placed within a phylogenetic framework, which will help to elucidate which lineages were diversifying in Antarctica.

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.

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