巴西酋龙的颌骨

巴山酋龙（Ｄａｔｏｕｓａｕｒｕｓ ｂａｓｈａｎｅｎｓｉｓ Ｄｏｎｇ ａｎｄ Ｔａｎｇ,１９８４）是四川盆地大山铺中侏罗侏罗世蜥脚类恐龙,亦称大头龙。其主要特征之,为硕壮的头骨,文中对保存于重庆自然博物馆的酋龙上下颌骨新材料进行较详细的记述。保存的前上颌骨上,高（前端）、厚分别为１２０ｍｍ,１２５ｍｍ和４０ｍｍ;上颌骨上为２８０ｍｍ;下颌齿骨高为１４５ｍｍ。估计每侧上、下颌齿数分别为１４和１２枚。牙     

巴山酋龙的颌骨

巴山酋龙 (Datousaurus bashanensis Dong and Tang ,1984)是四川盆地大山铺中侏罗世蜥脚类恐龙 ,亦称大头龙。其主要特征之一为硕壮的头骨。文中对保存于重庆自然博物馆的酋龙上下颌骨新材料进行较详细的记述。保存的前上颌骨长、高 (前端 )、厚分别为 120mm ,125mm和 40mm ;上颌骨长为 280mm ;下颌齿骨高为145mm。估计每侧上、下颌齿数分别为 14和 12枚。牙齿粗大 ,勺状 ,排列紧密。推测头骨长可达 6 7cm ,是已知蜥脚类恐龙中最硕大的。与大山铺同一地点其它蜥脚类相比 ,巴山酋龙的颌骨也不尽相同 ,这为进一步探讨其食性及古环境提供新的线索。     

白鱀豚额隆油、下颌油及皮脂油的脂肪酸组成

在齿鲸类的头部,有两个特殊的富含油脂的构造,即额隆和一对下颌脂肪体。在全身的皮下有很厚的皮脂层。Litchfield等(1974,1975)对齿鲸类中近20个属的额隆、下颌脂肪体和皮脂的脂质类型作比较研究,发现不同类群的油脂组分有差别,任何类群的额隆和下颌脂肪体的油脂--头脂的组分,与皮脂油的组分有明显区别,而额隆和下颌脂肪体的油脂组分是相近的。     

PLASTICITY OF JAW AND SKULL MORPHOLOGY IN THE NEOTROPICAL CICHLIDS GEOPHAGUS BRASILIENSIS AND G. STEINDACHNERI

I examined plasticity of jaw and skull morphology induced by feeding different diets in two species of the neotropical cichlid genus Geophagus. The two species possess different modes of development, which affect the size at which young begin feeding. I hypothesized that the difference in size at first feeding could lead to a difference in the amount of change inducible in the two species. The young of the substrate-spawning species, G. brasiliensis, which begin feeding at a smaller size, were predicted to be more plastic than those of the mouthbrooding species, G. steindachneri. The two diets used to induce differences were brine shrimp nauplii and chironomid larvae. Numerous measures of the jaw and skull differed significantly between groups fed the two diets but the amount of plasticity induced was small and would not present a problem for taxonomists. Contrary to my prediction, both the magnitude and pattern of plasticity induced in the two species was similar. Thus, mode of parental care and the size at which young begin feeding do not affect the degree of plasticity. Fish fed brine shrimp nauplii were longer in oral jaw region, but were shorter and shallower in the area behind the oral jaws. An additional group of G. brasiliensis was fed flake food to compare the results of this study to other studies. The differences in measures between fish fed brine shrimp diets and flake food diets were greater than those between fish fed brine shrimp and chironomid larvae. A possible role of plasticity for enhancing rather than retarding morphological evolution is discussed.     

A MAMMALIAN LOWER JAW FROM THE JURASSIC OF LINGYUAN, LIAONING

<正> In 1976, a right mandible of a Mesozoic mammal was collected by Messrs. Cheng Zhengwu and Yue Zhao of Institute of Geology, the Chinese Academy of Geological Sciences, from the Middle Jurassic in Lingyuan County, Liaoning Province, Northeast China (fig. 1), When they were studying the Mesozoic stratigraphy of that area. This fossil site is most probably from the same locality as that of Yabeinosaurus tenuis reported by C.C. Young in 1958. Both fossils are derived from the same horizon.