Cenozoic climate change and the evolution of North American mammalian predator ecomorphology

The trend of global cooling across the Cenozoic transformed the North American landscape from closed forest to more open grasslands, resulting in dietary adaptations in herbivores in response to shifting resources. In contrast, the material properties of the predator food source, muscle, skin, and bone, have remained constant over this transition, suggesting a corresponding lack of change in predator dietary adaptations. We investigate the North American mammal predator fossil record using a tooth shape metric and body mass, predicting that the former would exhibit stability. Instead, we found that mean molar morphology became more blade-like, with our tooth shape metric sharply increasing in the late Eocene and remaining high from the Oligocene onward. Subsequent tests in extant carnivorans reveal taxa with more blade-like teeth are prevalent in more open environments. Our results reveal an unexpected functional shift among North American predators in response to large-scale environmental changes across the Cenozoic.

Methods
Data is a combination of occurrence, morphological, diet and habitat data. The occurrence were collected from the New and Old Wrolds (NOW) and MIOMAP fossil mammal databases. The morphological data was collected from museum speciemens and published images. Diet and habitat data was collected from the liturature.