  We report on the specific heat determination of the anisotropic phase diagram
of single crystals of optimally doped SmFeAsO1-xFx. In zero-field, the
optimally doped compound displays a clear cusp-like anomaly in C/T with
{\Delta}C/Tc = 24 mJ/molK2 at Tc = 49.5 K. In magnetic fields applied along the
c-axis, we find pronounced superconducting fluctuations induced broadening and
suppression of the specific heat anomaly which can be described using
three-dimensional lowest-Landau-level scaling with an upper critical field
slope of -3.5 T/K and an anisotropy of {\Gamma} = 8. The small value of
{\Delta}C/Tc yields a Sommerfeld coefficient {\gamma} ~ 8 mJ/molK2 indicating
that SmFeAsO1-xFx is characterized by a modest density of states and strong
coupling.
