Habitat influences carnivoran skull development, new research reveals

Differences in skull shape and function across carnivorans stem not just from diet, as has long been observed, but also from a range of environmental factors in the animal’s habitat, according to a paper published Feb. 7 in Science Advances.

Carnivorans are the large mammalian order including dogs, cats and bears.

The research, by scientists at the American Museum of Natural History and UB, demonstrates there is far more variability in environmental influences of skull function and shape in carnivorans than has been understood.

“One of the main findings from this paper is that the anatomical variations we observed across species are related as intimately to diet as they are to several environmental factors,” says lead author Jack Tseng, assistant professor in the Department of Pathology and Anatomical Sciences in UB’s Jacobs School of Medicine and Biomedical Sciences and research associate at the museum. “These factors don’t necessarily have to do with feeding behavior or preference, but still can significantly influence how different skulls function as food processing tools.”

Together with co-author John Flynn, the Frick Curator of Fossil Mammals in the museum’s Division of Paleontology, Tseng developed sophisticated structural and biomechanical models of a broad range of skulls from carnivorans with every imaginable type of diet. They used the models to see how skull shape and size are related to and influenced by the environments of each species.

They found that, for example, sexual maturity and precipitation-related arboreality (how much rain falls in a habitat influences what species eat and how they interact with their environment) can generate structure-function relationships in the skulls of carnivorans that correlate with “masticatory performance.”

“This is a common theme between my different model organisms (carnivorans vs. humans),” Tseng explains. “The relationships between structure and function allow us to make predictions about how well parts of our body work given their anatomy, but factors influencing those anatomical variations do not necessarily have to be directly related to the functions those variations affect.

“In other words, understanding the proximal mechanisms of a structural system (be it a bone-crushing carnivore skull or a patient suffering from temporomandibular joint pain) is not the same as understanding the systemic pathways that underlie an evolutionarily adapted system or development of a pathological condition,” Tseng says.

The work was funded by the National Science Foundation and the Frick Fund of the American Museum of Natural History.