  We have calculated high temperature expansions for the momentum distribution
function $n_{\scriptscriptstyle\bf k}$ and the equal time spin and density
correlation functions $S({\bf q})$ and $N({\bf q})$ of the two-dimensional
$t$-$J$ model. On extrapolation to low temperatures we find that
$n_{\scriptscriptstyle\bf k}$ has a step-like feature at ${\bf
k}_{\scriptscriptstyle F}$ and $S({\bf q})$ has $2{\bf k}_{\scriptscriptstyle
F}$ as a characteristic wavevector, whereas $N({\bf q})$ has $2{\bf
k}_{\scriptscriptstyle F}^{\scriptscriptstyle SF}$ as a characteristic
wavevector. Here ${\bf k}_{\scriptscriptstyle F}$ and ${\bf
k}_{\scriptscriptstyle F}^{\scriptscriptstyle SF}$ are the Fermi wavevectors of
the nearest-neighbor square lattice tight-binding and spinless fermion models,
respectively. By comparison to the known results for one dimension this
suggests spin-charge separation in the two-dimensional $t$-$J$ model.
