Data from: Kinematics of chisel-tooth digging by African mole-rats

Mole-rats are known to use their protruding, chisel-like incisors to dig
underground networks of tunnels, but it remains unknown how these incisors
are used to break and displace the soil. Theoretically, different
excavation strategies can be used. Mole-rats could either use their head
depressor muscles to power scooping motions of the upper incisors (by
nose-down head rotations) or the lower incisors (by nose-up head
rotations), or their jaw adductors to grab and break the soil after
penetrating both sets of incisors into the ground, or a combination of
these mechanisms. To identify how chisel-tooth digging works, a kinematic
analysis of this behaviour was performed based on high-speed videos of 19
individuals from the African mole-rat species Fukomys micklemi placed
inside transparent tubes in a laboratory setting. Our analysis showed that
the soil is penetrated by both the upper and lower incisors at a
relatively high gape angle, generally with the head rotated nose-up.
Initially, the upper incisors remain approximately stationary to function
as an anchor to allow an upward movement of the lower incisors to grab the
soil. Next, a quick, nose-down rotation of the head further detaches the
soil and drops the soil below the head. Consequently, both jaw adduction
and head depression are jointly used to power tooth-digging in F.
micklemi. The same mechanism, but with longer digging cycles, and soil
being thrown down at smaller gape sizes, was used when digging in harder
soil.