The protoconodont genus Gapparodus seems to have an evolutionary trend of the increase of furrows, i. e. the trend from "two furrows type" to "three furrows type". This evolutionary trend is more or less similar to that of the Tremadocian euconodont Scolopodus. Little is known about the evolutionary trends of the coniform paraconodonts. The evolutionary trends of Wester-gaadodina seem to be manifested in three aspects as follows: CD the length/width ratio, (2) the size of basal and lateral openings, and (3) the direction of the lateral projections. The length/ width ratio increases gradually within the bicuspidate species, whereas the length/width ratio increases early and decreases late within the tricuspidate sclerits. The size of lateral openings decreases gradually within the bicuspidate species, while the size of basal and lateral openings decreases gradually within the tricuspidate sclerites, but there are few exceptions. The evolutionary development of the directions of the lateral projections within the tricuspidate species is more or less similar to that of the stipes of Graptoloidea. The lateral projections extended almost horizontally in the original form, and later they became reclined or reflexed in the intermediate form. During the Late Cambrian, the lateral projections extended vertically, with each other nearly parallel, and most species of tricuspidate Westergaadodina belong to this type. The evolutionary development of the directions of the lateral projections within the bicuspidate species seems to be less regular. The lateral projections of the original form extended vertically, with each other nearly parallel. The diverging lateral projections of different lengths appeared in the Late Cambrian. However, the lateral projections of the form that survived into the Ordovician still extended vertically, with each other nearly parallel.