Speakers Club Poster
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UC SANTA BARBARA Department of Earth Science Speakers Club WEBB 1100 • THURSDAY APRIL 19th., 2018 • 3:30 PM Two Oligocene ‘Notohippids’ Estuarine Response to Disturbance: (Mammalia, Notoungulata, Toxodontia) A Holocene Record of Storm Episodes and from the Central Chilean Andes: Seismicity as Preserved in Coastal Systems Taxonomy and Phylogeny John Munson Dillon Osleger Department of Earth Sciences Department of Earth Sciences UC Santa Barbara UC Santa Barbara Volcanoclastic deposits within the Abanico Predictions of future climate change in a warming Formation of the Andean Main Range of central environment suggest greater climate variability and Chile have recently produced new Cenozoic fossil amplitude. This shift in climate variability may be assemblages. Some Chilean faunas represent a expressed by an increase in severity of catastrophic time unsampled elsewhere in South America. These events, including droughts and high-intensity storms. rocks are an unanticipated source of fossils which Central and Southern California are particularly record an important period of South American sensitive to catastrophic events associated with mammal evolution. Here I describe two Oligocene these predictions as water reservoirs (supra and ‘notohippids’ from the Abanico Formation and sub surface) remain low and associated subsidence incorporate them into a phylogenetic analysis. provides space for flooding. Assessment of future ‘Notohippidae’ is an extinct paraphyletic group of climate variability within this region is dependent medium-dog-sized mammals endemic to South on a baseline of past events under varying climates. America from the Casamayoran (middle Eocene) to Existing records of past droughts and severe storms Santacrucian (early Miocene) South American Land have been constructed on a range of time scales, Mammal Age (SALMA). The name “Notohippidae,” including historical records, marine sediment cores, which translates to “southern horse,” reflects the dendrochronology, and lacustrine records. Central group’s convergent resemblance to horses. This and Southern California are also highly susceptible clade belongs to a diverse group of native South to powerful earthquakes which may leave a American herbivores, the notoungulates. SGOPV sedimentologic signature comparable to that of 3750, a cranium bearing a partial upper dentition, climate records. These archives provide a look at represents a new taxon. It was recovered from talus the impact of such extreme weather and seismic near Upeo, Chile, ~200 km SSE of Santiago and the events on the broader region, but few datasets first fossil described from this locality. SGOPV 3221, exist regarding how these hazards impacted the a nearly complete upper dentition, was collected most heavily populated parts of southern California from the Las Leñas drainage basin (100 km SSE of – its coastline. Santiago). It is tentatively referred to the Deseadan Campus Lagoon on the University of California (late Oligocene) taxon Rhynchippus brasiliensis. Santa Barbara (UCSB) campus and Las Salinas The phylogenetic analysis includes eight other Lagoon (now the Andree Clark Bird Refuge) in the ‘notohippids,’ three toxodontids, 2 leontiniids, and city of Santa Barbara are investigated in this study 4 ‘isotemnids.’ The monophyly of the ‘notohippids’ in order to better determine the frequency of past Eurygenium and Argyrohippus is resolved, but catastrophic events including storms related to ‘Notohippidae’ remains paraphyletic. Though the atmospheric rivers and co-seismic uplift/subsidence. relationships within ‘Notohippidae’ are poorly The objective of this investigation is to determine known, the specimens described here increase our environmental changes recorded within lagoon understanding of notoungulate diversity. systems along the Santa Barbara coastline through the mid- to late Holocene. Two specific research questions are addressed regarding hazards that impacted this system over the Holocene: A) What is the frequency of large storm events recorded within the sedimentological record? B) Is evidence found within Campus Lagoon and Las Salinas Lagoon for co-seismic uplift or subsidence? Presented is a detailed sedimentologic and geochemical analysis of sediment cores, constrained by radiocarbon dates from these two estuarine/ lagoon systems. These analyses better resolve the recurrence of large magnitude coastal events through the late Holocene. .