  The log-normal distribution represents the probability of finding randomly
distributed particles in a micro canonical ensemble with high entropy. To a
first approximation, a modified form of this distribution with a truncated
termination may represent an isolated galactic disk, and this disk density
distribution model was therefore run to give the best fit to the observational
rotation curves for 37 representative galaxies. The resultant curves closely
matched the observational data for a wide range of velocity profiles and galaxy
types with rising, flat or descending curves in agreement with Verheijen's
classification of 'R', 'F' and 'D' type curves, and the corresponding
theoretical total disk masses could be fitted to a baryonic Tully Fisher
relation (bTFR). Nine of the galaxies were matched to galaxies with previously
published masses, suggesting a mean excess dynamic disk mass of dex0.61+/-0.26
over the baryonic masses. Although questionable with regard to other
measurements of the shape of disk galaxy gravitational potentials, this model
can accommodate a scenario in which the gravitational mass distribution, as
measured via the rotation curve, is confined to a thin plane without requiring
a dark-matter halo or the use of MOND.
