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LATE MESOZOIC FISH FAUNA FROM WESTERN LIAONING, CHINA
- Jin Fan, Zhang Jiangyong, Zhou Zhonghe
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1995, 33(03):
169-193.
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Large samples of fossil fishes were collected from the Late Mesozoic non-marine Jehol Group (including the Yixian, Jiufotang, Shahai and Fuxin formations in ascending order) at 25 localities in western Liaoning, China (Fig. 1, Table 1). The new material enriches the composition of the Jehol fish fauna greatly. Our preliminary study indicates that this fish fauna is dominated by sturgeons (Peipiaosteidae: Yanosteus longidorsalis and Peipiaosteus pani), paddlefishes (Polyodontidae: Protopsephurus Iiui), diversified lycopterids (Lycoptera davidi, L. muroii, L. sinensis, L. sankeyushuensis, and Jinanichthys longicephalus), osteoglossids (Paralycoptera sp.), and possibly osteoglossomorphs (Huashia sp., ?Nieerkunia and an indeterminate fish); it also includes palaeonisciforms, amiiforms (Sinamia sp.), and a teleost incertae sedis (Longdeichthys Iuojiaxiaensis).
The lycopterids are characterized by the following combination of features: nasals tube-like, and separated by mesethmoid; temporal fenestra present on posterolateral region of cranium; hyomandibular with a distinct anteroventral process; antorbital semicircular in shape, 4—5 infraorbital bones, no supraorbital; inner margin of pectoral fin with a large unbranched ray; a full neural spine present on first preural centrum, no more than one epural, 6—7 hypurals, 3—5 uroneurals; cycloid scales with fine concentric circuli and with basal radii. Among the nominated genera which were referred or related to the family Lycopteridae in China, Lycoptera, Jinanichthys and Kuyangichthys can be ascribed to this family with certainty. Jinanichthys is distinguishable from Lycoptera by the elongated frontal, the nasals separated by the frontals and mesethmoid, the first infraorbital bone expanded anteroventrallya the third infraorbital semicircular in shape, the maxilla arched and overlain with a large oval supramaxilla, the dentary with a prominent coronoid process, and the ventral limb of the preopercle nearly as long as the dorsal limb.
The genus Asiatolepis Takai is almost identical to Lycoptera Müller except in no epural and 15 branched caudal fin rays. The genera Changichihys Su and Liaoxiichthys Su are both synonymous with Jinanichthys Ma et Sun. Jinanichthys longicephalus Ma et Sun is an invalid name of J. longicephalus (Liu et al.), and the latter is possibly a late synonym of Lycoptera fragilis Hussakof as well.
The four species of Lycoptera found in western Liaoning, especially L. davidi (Sauvage) and L. muroii (Takai) with a large number of specimens show some variations in the development of neural spines on the first preural centrum and ural centra 1—3, and in the number of uroneurals, hypurals and branched caudal fin rays. Lycoptera tokunagai Saito is considered a synonym of L.davidi for its features (e. g. , body slender, head small, pectoral fin nearly extending to the origin of the pelvic, anal fin decidedly in front of the dorsal, and more vertebrae and anal fin rays) present a series of intermediate states between these two species, and the differences between L. tokunagai and L. davidi are obliterated.
The genus Paralycoptera (including P. wui Chang et Chou and P. changae Ma et Sun) could be assigned to the family Osteoglossidae for it is more closely related to Osteoglossum than to Lycoptera (e. g. , heavily toothed long jaws, two extremely expanded infraorbital bones posterior to the orbit, high and narrow kidney-shaped opercle, rather short ventral limb of preopercle, parasphenoid bearing a developed basipterygoid process and strong teeth on its ventral side, and scales slightly reticulated and sparsely granulated on the apical region). Tanolepis ningiiagouensis Jin is synonymous with P. changae Ma et Sun and should be discarded.
