Abstract
Southeast Asia boasts some of the world's most diverse ecosystems, yet it has experienced a dramatic decline in biodiversity due to extensive deforestation in recent decades. Understanding how species adapted to past habitat loss could provide valuable insights for developing effective conservation strategies to address current threats. We apply state-of-the-art isotope measurements of enamel-bound zinc (δ(66)Zn) and nitrogen (δ(15)N(enamel)) analyses to fossil mammal teeth from Coc Muoi [148 to 117 thousand years (ka) and Duoi U'Oi (70 to 60 ka)], Vietnam. Alongside published regional data (δ(66)Zn, δ(13)C, and δ(18)O), we explore how different taxa adapt their diets and behaviors in the face of climatic and environmental changes. We show that foraging in diverse habitats and diversifying food consumed is associated with extant species, while extinct or locally extirpated taxa show these traits to a lesser extent. We underscore the precariousness of certain species and the pressing need for robust conservation policies to safeguard Southeast Asia's biodiversity.