Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan
165
PARH
HYU1
5mm
Fig. 43. Aokiichthys otaigen. et sp. nov., caudal region of the holotype, KMNH VP 100,173.
origin is vertical with the anal origin. The first dorsal fin pterygiophore is inserted
between the first and second caudal vertebrae. The dorsal fin base is contained 1.9
times in the anal fin base. The pectoral fin elongates and extends over the pelvic
insertion. The caudal fin is emarginate. The number ofprincipal dorsal fin rays is
11. There are 11 dorsal fin pterygiophores. The number ofprincipal anal fin rays
is 19. There are 19 anal fin pterygiophores. The principal dorsal and anal fin rays
are preceded by two small unbranched accessory rays respectively. Sixteen pectoral
fin rays arevisible. Six pelvic fin rays are visible. There are 17 principal caudal fin
rays (1,7,8,1). The gape of the mouth is large. The lower jaw is long and narrow.
The dentary bears small canine like teeth on its oral margin. The suture between
the dentary and anglo-articular is not visible and the posterior part ofthe lower jaw is
poor in preservation. The premaxilla and maxilla bear small canine like teeth.
Three large teeth are visible on the parasphenoid. The parasphenoid teeth are
larger than the premaxillary, maxillary and dentary teeth. The premaxillary and
maxillary teeth are slightly larger than the dentary teeth. Seven branchiostegal rays
are visible (Fig. 42). The cleithrum is wide and has two ridges at the upper part.