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Getting a grip on the evolution of grasping in musteloid carnivorans: a three-dimensional analysis of forelimb shape.

Fabre A.-C., R. Cornette, G. Slater, C. Argot, S. Peigné, A. Goswami and E. Pouydebat
Journal of Evolutionary Biology 26(7):1521-1535
Lyncodon patagonicus
The ability to grasp and manipulate is often considered a hallmark of homi-
nins and associated with the evolution of their bipedal locomotion and tool
use. Yet, many other mammals use their forelimbs to grasp and manipulate
objects. Previous investigations have suggested that grasping may be derived
from digging behaviour, arboreal locomotion or hunting behaviour. Here,
we test the arboreal origin of grasping and investigate whether an arboreal
lifestyle could confer a greater grasping ability in musteloid carnivorans.
Moreover, we investigate the morphological adaptations related to grasping
and the differences between arboreal species with different grasping abilities.
We predict that if grasping is derived from an arboreal lifestyle, then the
anatomical specializations of the forelimb for arboreality must be similar to
those involved in grasping. We further predict that arboreal species with a
well-developed manipulation ability will have articulations that facilitate
radio-ulnar rotation. We use ancestral character state reconstructions of life-
style and grasping ability to understand the evolution of both traits. Finally,
we use a surface sliding semi-landmark approach capable of quantifying the
articulations in their full complexity. Our results largely confirm our predic-
tions, demonstrating that musteloids with greater grasping skills differ mark-
edly from others in the shape of their forelimb bones. These analyses
further suggest that the evolution of an arboreal lifestyle likely preceded the
development of enhanced grasping ability