  Half-quantum vortices in spin-triplet superconductors are predicted to host
Majorana zero modes and may provide a viable platform for topological quantum
computation. Recent works also suggested that, in thin mesoscopic rings, the
superconducting pairing symmetry can be probed via Little-Parks-like
magnetoresistance oscillations of periodicity $\Phi_0 = h / 2e$ that persist
below the critical temperature. Here we use the London limit of Ginzburg-Landau
theory to study these magnetoresistance oscillations resulting from thermal
vortex tunneling in spin-triplet superconducting rings. For a range of
temperatures in the presence of disorder, we find novel oscillations with an
emergent fractional periodicity $\Phi_0 / n$, where the integer $n \geq 3$ is
entirely determined by the ratio of the spin and charge superfluid densities.
These fractional oscillations can unambiguously confirm the spin-triplet nature
of superconductivity and directly reveal the tunneling of half-quantum vortices
in candidate materials such as Sr$_2$RuO$_4$ and UTe$_2$.
