  The time evolution of a dilute atomic boson-fermion mixture is studied at
zero temperature, when the external magnetic field is brought close to a
interspecies Feshbach resonance. On short time scales we find that before a
collapse or phase separation of the mixture can occur, oscillations between
fermionic atoms and heteronuclear molecules dominate the dynamics. Applying the
model presented here to a trapped mixture of $^{40}$K-$^{87}$Rb atoms, we find
that the predicted oscillations can be revealed in degenerate mixtures of these
atoms.
