Intermediates often have little or no selective value. Too distinct to have evolved gradually. Gingerich's summary of evolutionary rates. The crucial difference between punctuated equilibrium and phyletic gradualism concerns the rate of evolution at, and between, splitting events. Problem not yet entirely resolved.
Saltational change seems to occur in some lineages, gradual change in others.
Sheldon's study of Ordovician Welsh trilobites. In 8 lineages, pattern of change is gradual rather than punctuated. Unlikely, as thin bone would have broken easily. Breakage may be advantageous. An individual with an intramaxillary joint suddenly appeared and was favored.