EAR-PF: Paleoecology of marine mammal herbivory: a multidisciplinary analysis of fossil sirenians, desmostylians and sloths from the Eastern Pacific Ocean

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Dr. Jorge Velez-Juarbe has been awarded an NSF Earth Science Postdoctoral Fellowship to study the ancient ecology of co-occurring extinct marine mammal herbivores from the Eastern Pacific region. Seacows (manatees and dugongs) are the only extant marine mammal herbivores. However, until about 11 million years ago, two other groups of marine mammals, desmostylians in the Northern Pacific region; and aquatic sloths in the Southeastern Pacific region once occurred alongside seacows. To understand how these three groups of marine herbivores interacted with each other, two approaches will be taken. First, description and measurements of the shape and size of the skulls, mandibles and teeth will help formulate hypotheses about the feeding modes of the species in each group. The second approach will use stable isotopes, more specifically, carbon and oxygen, obtained from small tooth or bone samples. The carbon isotopes will aid in the determination of the type of marine plants (either seagrasses, seaweed or a combination of the two) that the different species within each group were consuming. Oxygen isotopes will then provide information regarding their habitats, and will help determine whether the different species were spending more time in marine, brackish or freshwater environments. The goal of this project is to determine if these various groups were sharing the resources (more specifically, marine vegetation) and if so, how was it achieved; and secondly, to compare these multispecies assemblages with others where only seacows were present. The results of this project will be relevant to questions about ocean productivity patterns in the last 20 million years, and can also further our understanding of current changes in marine habitats.This project will be carried out at the Department of Geological Sciences, California State University Fullerton (CSU F) and at the John D. Cooper Center. This will give Dr. Velez-JUarbe the opportunity to train students and volunteers in museum curation through (STEM)2 and Project BONES intern programs, as well as co-teach paleontology courses. CSUF is also one of the top institution awarding degrees to Hispanic and other minority students in the US. As a Hispanic, Dr. Velez-Juarbe will be able to contribute to broader efforts in encouraging minority groups pursuing STEM degrees.