  Magnetic correlations near the magneto-structural phase transition in the
bilayer iron pnictide parent compound, BaFe$_2$As$_2$, are measured. In close
proximity to the antiferromagnetic phase transition in BaFe$_2$As$_2$, a
crossover to three dimensional critical behavior is anticipated and has been
preliminarily observed. Here we report complementary measurements of
two-dimensional magnetic fluctuations over a broad temperature range about
T$_N$. The potential role of two-dimensional critical fluctuations in the
magnetic phase behavior of BaFe$_2$As$_2$ and their evolution near the
anticipated crossover to three dimensional critical behavior and long-range
order are discussed.
