Bulletin of the Mizunami Fossil Museum

Bulletin of the Mizunami Fossil Museum No. 3

The purpose of this paper is the morphological description of pharyngeals and their teeth in Chinese genera P,.ocypris and Cypriuus (subgenus Mesocyprinus), and the fossil pharyngeal teeth collected from the Miocene Mizunami Group, and discussion of the phylogenical relationship in these fishes.

(1) Procypris. The pharyngeal is moderately elongate and the anterior angle undeveloped. Teeth are arranged in three rows (2,3, 4/ 4, 3, 2). The teeth themselves show a peculiar character: the occlusal surface is performed, not on one side as in other cyprinids, but on both lateral and medial sides in each tooth (except in A1 tooth). Grooves are constructed on both of these occlusal surfaces; in spite of the peculiarity in the location of the occlusal surfaces the grooves on these surfaces are structurely homologous with that of C. carpio.

(2) Mesocyprinus. The pharyngeal, as a whole, is similar to that of C. carpio; however, the pitted surface is rather narrow. The teeth are arranged in four rows (? / 3, 1. 1. 1). Teeth are smaller and less differentiated than those of C. carpio. Conclusively, the teeth of Mesocyprinus remain at pre-carpio level.

(3) The teeth fossils from the Mizunami Group are studied. Limited to the outline of the occlusal surface, these teeth are identical with that of C. carpio; on the other hand, there are some features not identical with that of carpio itself in these teeth. Conclusively, the fossil species is classified to the genus carpio, but already derived from carpio.

Summarizing the result of the present study, Procypris is a form specialized from the primitive pre-Cyprinus level, while Mesocyprinus is a relict form, remains at pre-carpio level in the limitation of the genus Cyprinus.