Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan

Early Cretaceous Freshwater Fish Fauna in Kyushu, Japan 187
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Fig. 56.
Wakinoichthys aokii gen. et sp. nov., caudal skeleton of the paratype, KMNH
VP100.141.
above the 21th abdominal vertebra. Three posterior supraneurals are cylindrical
and the other supraneurals are wide and leaf-shape with a ridge running from a
dorsal end to a ventral end. The first preural centrum bears the wide parhypural.
The neural arch and spine of the first preural centrum are complete. Four hypurals
are visible. The first hypural is the largest. The second hypural is cylindrical and
about one third of the first one in width. There is a space between the second and
the third hypurals. The third hypural is slender and cylindrical. There are two
ural centra. One uroneural is visible. The anterior ends of uroneurals are not
visible. Epurals are not visible (Fig. 59).
In KMNH VP 100,185, the first dorsal fin pterygiophore is inserted between the
neural spines of the fifth and sixth caudal vertebrae. The dorsal fin base is
contained 2.2 times in the anal fin base. The number of principal dorsal fin rays is
12. There are 12 dorsal fin pterygiophores. The number of principal anal fin rays
is 20. There are 20 anal fin pterygiophores. The principal dorsal and anal fin rays
are preceded by two small unbranched accessory rays respectively. Ten pectoral fin
rays are visible. There are 18 principal caudal fin rays (1,8,8,1). The total number
of vertebrae is 49, with 24 caudal vertebrae. The number of ribs is 23. There are
two ural centra. The first ural centrum is larger. The first and the second hypurals
are attached to the first ural centrum. The first hypural is slightly larger than the
second hypural. Five hypurals are present.
In KMNH VP 100,186, the first dorsal fin pterygiophore is between the sixth