Data from: The biomechanics of foraging determines face length among kangaroos and their relatives

Increasing body size is accompanied by facial elongation across a number
of mammalian taxa. This trend forms the basis of a proposed evolutionary
rule, cranial evolutionary allometry (CREA). However, facial length has
also been widely associated with the varying mechanical resistance of
foods. Here, we combine geometric morphometric and computational
biomechanical analyses to determine whether evolutionary allometry or
feeding ecology have been dominant influences on facial elongation across
sixteen species of kangaroos and relatives (Macropodiformes). We found no
support for an allometric trend. Nor was craniofacial morphology strictly
defined by dietary categories, but rather associated with a combination of
the mechanical properties of vegetation types and cropping behaviours used
to access them. Among species examined here, shorter muzzles coincided
with known diets of tough, resistant plant tissues, accessed via active
slicing by the anterior dentition. This morphology consistently resulted
in increased mechanical efficiency and decreased bone deformation during
incisor biting. Longer muzzles, by contrast, aligned with softer foods or
feeding behaviours invoking cervical musculature that circumvent the need
for hard biting. These findings point to a potential for craniofacial
morphology to predict feeding ecology in macropodiforms, which may be
useful for species management planning and for inferring palaeoecology.