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

Jorge Velez-Juarbe博士被授予美国国家科学基金会地球科学博士后奖学金，研究东太平洋地区共同发生的灭绝海洋哺乳动物-食草动物的古代生态学。海牛（海牛和儒艮）是唯一现存的海洋食草哺乳动物。然而，直到大约1100万年前，另外两组海洋哺乳动物——北太平洋地区的近毛纲动物；东南太平洋地区的水生树懒曾经与海鸟一起生活。为了了解这三种海洋食草动物是如何相互作用的，我们将采取两种方法。首先，对头骨、下颌骨和牙齿的形状和大小的描述和测量将有助于对每一组物种的进食方式做出假设。第二种方法将使用稳定同位素，更具体地说，是从小牙齿或骨骼样本中获得的碳和氧。碳同位素将有助于确定每组中不同物种所消耗的海洋植物的类型（海草、海藻或两者的组合）。氧同位素将提供有关其栖息地的信息，并将有助于确定不同物种是在海洋、半咸淡水还是淡水环境中度过更多时间。该项目的目标是确定这些不同的群体是否共享资源（更具体地说，海洋植被），如果是，是如何实现的；其次，将这些多物种组合与其他只有海鸟的组合进行比较。这个项目的结果将与过去2000万年海洋生产力模式的问题有关，也可以进一步加深我们对海洋栖息地当前变化的理解。该项目将在加州州立大学富勒顿分校（CSU F）地质科学系和约翰D.库珀中心进行。这将使Velez-JUarbe博士有机会通过（STEM）2和Project BONES实习项目培训学生和志愿者，并共同教授古生物学课程。加州大学旧金山分校也是美国授予西班牙裔和其他少数族裔学生学位的顶尖学府之一。作为一名西班牙裔，贝雷兹-华尔贝博士将能够为鼓励少数族裔攻读STEM学位做出更广泛的贡献。

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.