中华弓鳍鱼在吉林东部的发现

本文扼要记述了发现于吉林东部罗子沟地区大拉子组的中华弓鳍鱼属一新种——Sinamialuozigouensis,推测它可能生存于早白垩世早期;并且认为我国学者早先提出的关于北美现生弓鳍鱼类的起源理论是可以相信的。

DISCOVERY OF SINAMIA FROM EAST JILIN

Sinamia,as a genus of Sinamiidae,has only been found in China so far.Thispaper describes a new species which is named Sinamia luozigouensis.The material re-ferred to this new species only consists of four imperfect specimens beloning to two in-dividuls,and was collected in.the summer of 1980 by Ma Fenzen and the present author,from Luozigou Farm,Wang Qung,Jilin Province.According to the demonstration of specimens,the new species Sinamia luozigou-crisis is most similar to Simamia zdanskyi(Stensi(o|¨),1935).in the following characters:the general shape of the body,the construction of the opercular system,the unpairedand five-sided parietal,the total number of the rays of the dorsal fin,the shape of thecaudal fin,and the rhomboid and ganoine-coating scales.On the other hand,the new species differs clearly from Sinamia zdanskyi in atleast four characters:First,the anterior part of the parietal extends forwards moredistance between the most posterior parts of the frontals than in Simamia zdanskyi,The extension is almost half of the length of the parietal,but about one third of thatin the species Sinamia zdanskyi.Second,the dorsal fin beginning of Sinamia luozi-gouensis is almost opposite to or a bit ahead of the midpoint of the distance betweenthe pectoral and pelvic fins,it is,however,obviously behind the point in Sinamiazdanskyi.Third,the scale-lobe of the new species is even more degenerate as com-pared with that of Sinamia zdanskyi.Finally,there are more scale rows in Sinamialuozigouensis than in Sinarmia zdanskyi,and most of the trunk-scales are not serratedon the posterior margin.In terms of above mentioned characters,a new species is made,and classified in the genus SinamiaIt is embedded in a dark grey flag-siltstone or grey oil-bearing silty shale which is part of the oil-bearingsection of Dalazi Formation,and which,in addition to Sinamia luozigouensis,contains also other primi-tive teleostei.Judging from the bed,Sinamia luozigouensis could be considered to be existing in theearly stage of Early Cretaceous.Although it is the first time that Sinamia is discovered in the eastern part of Jilin Province,itexpands the distribution of Sinamiidae towards northeast.And it is believable that Amia calva originatedprobably from Eurasia,mainly from the area of China,and then spread to North America(Liu,1961).