I am still unable to create the back side of the sphere in a realistic perspective to my eye, but I think this is closer than just using the (-) spherize filter.
I made two thicknesses of grids, so that the back side would look further away and used a combination of lens distortion then transform scale instead of the (-) spherize.
Bevel and emboss layer style were applied and committed before distorting so that the layer styles would be transformed by the distortion.
dinasaur image borrowed from internet:
www.readmyday.co.uk/.../rw_stegosaurus_180.jpg
forum discussion http://forums.dpreview.com/forums/read.asp?forum=1006&message=26418157