摘要
记述了山东龙口黄县洼里煤矿早始新世黄县组二段油页岩中的鱼化石。该鱼身体狭长,背鳍位置靠后;额骨侧面有长形的、狗鱼所特有的副筛骨;额骨甚长;顶骨相对来说甚短;口裂较长;齿骨、前上颌骨及颚部许多骨片均生有扁而尖的牙齿,但上颌骨口缘光滑;外翼骨甚粗壮;鳃盖骨略呈长方形;前鳃盖骨较直,中部略收缩,上、下枝夹角大(约为１３０°);匙骨纵枝短而水平枝长大。困此属于狗鱼科中惟一的狗鱼属是毫无疑问的。根据其头长与体长之比、额骨及顶骨的形状和比例以及背鳍条数目与狗鱼属其他种的不同,我们将它订为一个新种——龙口狗鱼。黄县的化石是狗鱼渐新世以前在北美以外地区的首次发现,也是狗鱼化石在亚洲的首次发现。黄县位于北纬３７°７′,远较现生狗鱼在亚洲分布的地区(４３°和４６°以北)靠南。而始新世全球气候偏暖,巨南北温差较小,始新世狗鱼或较现生种类更适应较温暖的气候。早始新世狗鱼在中国的发现为当时跨太平洋鱼类区系的存在提供了进一步的证据。
Pikes (Esocidae) are freshwater fishes now dwelling in northern hemisphere, most of them in cold waters south to the polar circle. The family contains only one genus ( Esox) with five Recent species. Among them two appear in China, one (Esox reicherti) in the northeastern part of China, in the Amur, Sungaria and Wusuli rivers' valley; the other (E. lucius) in the Ertys River in Xin-jiang, northwestern China (Meng et al. , 1995). The finds of the Late Cretaceous, Paleocene and Eocene pikes were so far restricted to North America although their distribution became much wider starting from the Oligocene (Cavender et al. 1970; Sychevskaya, 1974, 1976; Gaudant, 1978, 1987; Wilson, 1980, 1981, 1984; Wilson et al., 1992; Grande, 1999). Thus, the fossil pike described in this paper is the first discovery of its kind from the early Eocene (or late Paleocene) outside of North America.The specimens of pikes described in this paper were collected from the Member 2 of the Huang-xian Formation in Wali Coal Mine, Huangxian County, Longkou, Shandong Province (Fig. 1) . No remains of vertebrates other than fish were found from the Huangxian Formation. Its correlation with the Wutu Formation in the nearby Wutu Basin was based on pollen (Paraalnipollenites-Betulaepolle-nites plicoides-Polypodiaceaesporites assemblage) and ostracods (e. g. Eucypris wutuensis) found in both formations. The age of the Wutu Formation has been considered as early Eocene by the findings of Homogalax wutuensis and Heptodon niushanensis ( Chow and Li, 1965). A big variety of fossil mammals belonging to several big groups were discovered recently from the Wutu Formation. Based on the study of the phylogeny of these groups combined with paleobiogeographic, paleoclimatic and biostratigraphic studies of North America and East Asia some researchers suggest the possibility of the age of the Wutu Formation as late Paleocene (Beard and Wang, 1995; Tong and Dawson, 1995; Beard, 1998; Beard and Dawson, 1999) . Associated with the pike were disarticulated bones of amiids which are under description by the present authors.
出处
《古脊椎动物学报》
CSCD
北大核心
2002年第2期81-96,共16页
Vertebrata Palasiatica
基金
国家自然科学基金重点项目(编号:48932010)
科技部973国家重点基础研究发展规划项目(编号:G2000077708)资助
关键词
山东龙口
始新世
狗鱼化石
中国
Longkou
Shandong
Eocene
pike
first discovery in China
