When I use the option “Set Draw Style” → FeatureAge (or any other option in this menu), I do not automatically get a color bar or color scale (as I do get with a raster). I understand the colors come from a cpt file, so it should be possible to produce one manually outside of GPlates (which is an unnecessary hassle). Problem there is, I don’t get the name of the cpt and do not know how GPlates uses the ages of the features to scale.
The two draw styles you see under
FeatureAge are builtin. But once you click
Add you’ll be able to create a third (user-defined) draw style and enter your own CPT filename. GPlates maps feature age to colour by subtracting the current reconstruction time from each feature’s age (time of appearance) and that value is used to lookup the CPT (ie, convert value to colour for each feature).
Also this thread goes into more discussion on this.
Most users here use GMT to produce CPTs, however the symbology overhaul will look into using the builtin palettes (accessible to rasters) for vector data also.
I’ll look into that.