Meeting Abstract
Seacows (manatees and dugongs) are the only extant marine mammal herbivores. However, the fossil record reveals two other groups of marine mammal herbivores that co-existed with sirenians in the Neogene: desmostylians, in the northern Pacific region; and thalassocnine sloths, in the southeastern Pacific region. There is no extant analog for these co-occurring species of marine herbivore assemblages in the northern Pacific (sirenians and desmostylians) and southeastern Pacific (sirenians and thalassocnines). So, how did these multiple, co-occurring marine herbivores partition their resources? To undertake this problem, I use a multidisciplinary approach to evaluate the paleoecology of sirenians, desmostylians and thlassocnines that combines stable isotope geochemistry with ecomorphological and body size data. The first approach examines isotopic values of δ13C and δ18O from sirenians, desmostylians and thalassocnines, obtained from their enamel and bone samples, which reflect their diet and habitat, respectively. Second, morphological data from the skull, teeth and jaws clarify ecologically linked functional traits that will be used to make inferences about feeding modes. Third, body size estimates clarify niche partitioning from nonmorphological dimension. This combined multidisciplinary approach aims to determine: 1) What kind of marine vegetation did each group consume; 2) ecological interactions between the groups; 3) differences between these multigroup marine mammal assemblages, compared to sirenian-only multispecies assemblages.
