optional arguments. So far these include: legend, a logical value indicating whether or not to plot a figure legend (defaults to legend=TRUE); labels, a logical value indicating whether or not to plot trait labels (defaults to labels=TRUE); split, a numeric vector indicating the fraction of the horizontal dimension to use for the tree & heatmap, respectively (defaults to split=c(0.5,0.5)); xlim, ylim, & mar, defined as in par; and ftype, lwd, and pts as defined in plotSimmap.