Carnivora Skull Shape Depends on More Than Just Diet

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Heat map of a carnivora skull.

Typical skull shapes of carnivoran species living in dry areas, modeled above, may be different from those in rainier locales, because food availability varies.

© Z.J. Tseng et. al.


It turns out, you’re not what you eat—at least, if you’re a mammal belonging to the order Carnivora.

New research has found that for this group of mammals—which includes species as varied as raccoons, pandas, and elephant seals—nondietary factors can be just as important, if not more so, in determining skull form and function.

 

[Poll: Which species has a skull that is more similar to a hyena’s—wolf, or mongoose? The researchers found more similarities in the overall shapes and biomechanical properties of the skulls of mongooses and hyenas. Congrats to all who you voted mongoose in our March newsletter poll!]

 


“For years, conventional thought surrounding carnivoran skull shape followed the ‘you are what you eat’ paradigm, where distantly related species evolve similar skulls because of shared dietary needs,” said Z. Jack Tseng, assistant professor of pathology and anatomical sciences in the Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo and a research associate at the Museum. “We found that to be a dramatic oversimplification.”

 

Seven side-by-side comparisons of skulls and heat maps.

Pairs of skulls with shape changes based on factors including age at sexual maturity, diet, and others. Warmer colors indicate extruding shape change (expansion), while cooler colors show shrinking shape change (reduction).

© Science Advances/Z.J. Tseng et. al.


In a study led by Zheng and coauthored by John Flynn, Frick Curator of Fossil Mammals in the Museum’s Division of Paleontology, data from more than 50 living species was used to create shape and biomechanical models representing a wide range of diets, from exclusive carnivores like lions to herbivores like pandas and omnivores like raccoons. 

The models allowed researchers to examine how skull size, shape, and bite performance varied when compared with nondietary factors such as habitat, life expectancy, and movement, among others.

 

Red panda with bamboo leaves in mouth.

A red panda, one of the omnivorous species in the mammalian order Carnivora, eating bamboo leaves.

Courtesy of Mathias Appel/ Flicker


Results showed that not only did nondietary factors influence skull shape and bite, but that variables such as age at sexual maturity and precipitation rates in a species’ environment can have a strong influence on bite performance. 

“You wouldn’t think that how many raindrops fall on an animal’s head each year could tell you what their skull looks like, so that was definitely an unexpected finding,” said Flynn. “But this precipitation factor is probably a proxy for something else having to do with the species’ environment. For example, a wet forest might have greater food availability than a dry habitat, and that would influence the skull’s shape.”

 

The study was published today in the journal Science Advances

 

 

Tags: carnivore