吉林省公主岭早白垩世泉头缍网形蛋（Dictyoolithus）一新科     

王强昝淑芹  金利勇陈军 《吉林大学学报(地球科学版)》2006,36(2):153-157

报道了吉林省公主岭早白垩世泉头组发现的一窝恐龙蛋化石。蛋化石近圆形，蛋壳厚度1．4～1．7mm，蛋壳外表面均匀分布椭圆形或圆形大小不一的凹坑；蛋壳层由2、3个呈分树枝状的基本结构单元叠加而成，蛋壳基本单元之间气孔道阔大而不规则，靠近蛋壳外表面的基本结构单元相互连姑、融合形成一层相对致密的薄层。据以上特征将其归为网形蛋科（Dictyoolithidae），网形蛋属（Dictyoolithus），定为一新种：公主岭网形蛋（Dictyoolithus gongzhulingensis oosp.nov）。公主岭网形蛋是网形蛋类化石在中国东北地区的首次发现，同时也是早白垩世地层中网形蛋化石新的发现。  相似文献   

A fossil insect egg on an Early Cretaceous conifer shoot from the Wealden of Germany     

《Cretaceous Research》2015

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Do fecundity‐time models really predict extreme optimal egg sizes?          下载免费PDF全文

Elena K. Kupriyanova  Dmitry Yu. Mikhin 《Marine Ecology》2015,36(4):873-886

In 1973, Vance published a mathematical model that explains differences in reproductive strategies such as planktotrophy and lecithotrophy found in marine invertebrates. The original model Vance (The American Naturalist, 107 , 339–352) traded fecundity against development time and resulted in a U‐shaped fitness function suggesting that only extreme levels of egg provisioning (referred to as egg size) are evolutionarily stable. Several later models independently predicted evolutionary stability of extreme egg sizes, and this has been commonly interpreted as a proof that the Vance model, albeit oversimplified, reflects the fundamental evolutionary principle of disruptive egg size evolution in marine invertebrates. However, empirical studies of the last several decades have illustrated that intermediate levels of egg provisioning are commonly observed in nature. As a result, the recent modifications of the original Vance model have attempted to explain evolution of such intermediate strategies. Here we re‐examine the earlier fecundity‐time models of the ‘Vance family’ and show that only Vance and its minor modification by Grant (The American Naturalist, 122 , 549–555) invariably predict evolutionary stability of extreme egg sizes. Most modifications of the original Vance model in fact can predict at least some intermediate optimal egg sizes and reproductive strategies. There is no reason to assume that selection towards extreme egg sizes is the driving force in the evolution of marine invertebrate life histories.  相似文献   

不同卤虫卵孵化的比较研究   总被引：1，自引：0，他引：1  

廖永岩  杨小静  邱旭光 《海洋科学》2003,27(7):71-74

分别选取进口质量较好卤虫卵、进口质量较差卤虫卵、台湾产卤虫卵和天津产卤虫卵进行标准条件孵化、自然条件孵化及去壳卵孵化.结果发现,天津产卤虫卵,颜色、形状正常,每1 g卵数为19×104,孵化率最高,达94.0%.质量较差的进口卵,颜色、形状不太正常,每1 g卵数为35×104,孵化率最差.在标准和自然条件下,卤虫卵均在36h达最高孵化率,但标准条件下的孵化率高.去壳卵的孵化率最高,孵化24 h时,最高孵化率达96.8%比标准条件孵化时快近12 h.但去壳卵易结团或结块下沉,不易漂浮.  相似文献   

Design of A Bionic Spudcan and Analysis of Penetration and Extraction Performances for Jack-up Platform     

GUO Sheng  ZHUANG Hong  TANG Wen-xian  WU Wen-le  LIU Qin  WANG Yue-yang 《中国海洋工程》2020,(1):80-88

The mechanisms of soil structure interaction have drawn much attention in the past years in the installation and operation of jack-up platform. A bionic spudcan produced by biomimetic of egg and snail shell is proposed, and the performance of the penetration and extraction are analyzed by numerical method. The geometric contour of egg and snail shell is measured, and its mathematical model is established respectively. According to the structure of existing spudcan of jack-up platform, three kinds of typical biomimetic spudcan are designed. Furthermore, numerical analysis models of biomimetic spudcan are established respectively to study the soil structure interaction mechanism in the process of penetration and extraction, and contrastive analysis of resistance characteristics are carried out. To conclude, the results show that the biomimetic spudcan facilitates the platform installation, and it is also beneficial to the improvement of the bearing capacity of spudcan.  相似文献   

天台盆地恐龙蛋化石结构和组分研究     

陈克樵  徐和聆 《岩矿测试》2000,19(1):45-50

采用扫描电镜、电子探针和Ｘ射线粉末衍射分析技术,研究了浙江天台盆地ＴＢ－１恐龙蛋化石的结构和组分。初步了解这个含似蛋白和蛋黄的恐龙蛋化石的结构和组分为;含铁钛的硅酸盐矿物售合体（蛋壳表层）、灰褐色方解石（蛋壳内层）、浅米黄色方解石（壳内矿物层）、白色石膏（腔内似蛋白矿物）和米黄色萤石（腔内似蛋黄矿物）。  相似文献   

河南西峡晚白垩世恐龙蛋化石壳碳同位素组成特征及其意义     

朱光有  钟建华 《地球化学》2000,29(5):475-479

利用显微镜和碳同位素分析法对自河南西峡盆地晚白垩世的１６枚恐龙蛋化石进行了研究。在显微镜下观察到恐龙蛋化石壳由原生碳酸盐矿物和次生碳酸盐矿物两部分组成。利用图像分析法得到了两者所占的比例分别为６０．５％和３９．５％。恐龙蛋内充填的次生碳酸盐矿物的δ＾１３Ｃ值在－５．６３‰￣－５．６８‰之间,平均为－５．６５‰。恐龙蛋化石壳的δ＾１３Ｃ同位素值在－５．８８‰￣－７．７９‰之间。经计算,获得了恐龙蛋壳  相似文献   

Comparative reproductive biology of two southwestern Atlantic populations of the hermit crab Pagurus exilis (Crustacea: Anomura: Paguridae)     

Mariana Terossi  Lucas S. Torati  Ivana Miranda  Marcelo A. Scelzo  Fernando L. Mantelatto 《Marine Ecology》2010,31(4):584-591

Pagurus exilis (Benedict, 1892) is an endemic South Atlantic hermit crab with a distribution ranging from Rio de Janeiro State, Brazil, to Buenos Aires Province, Argentina. The present study analyzed the reproduction of two populations at the extremes of this geographical distribution, and compared their reproductive period, fecundity, and changes in egg size and egg volume during the incubation period in order to assess the variability over this latitudinal range. Hermit crabs were collected monthly over a 2‐year period. In total, 108 females were analyzed for Brazil (44 non‐ovigerous and 64 ovigerous), and 141 for Argentina (87 non‐ovigerous and 54 ovigerous). Reproduction in Brazil occurs year‐round, with peaks in the fall and winter seasons; in Argentina reproduction occurs only in spring and summer. The Brazilian ovigerous females were significantly larger than the Argentina ones (Brazil: SL = 5.33 ± 1.45 mm; Argentina: SL = 4.15 ± 0.52 mm; P < 0.001). The fecundity was 1447 ± 831 eggs (317 to 2885) in Brazil and 987 ± 711 eggs (114 to 2665) in Argentina, with a trend towards higher fecundity in Brazil. Eggs in the Argentina population were larger than those in Brazil for all the three stages investigated, and no changes in egg volume were found during egg development for both populations. The reproductive traits of the two populations showed some important differences, which may reflect adaptations to local environmental conditions, demonstrating a high plasticity of reproductive features of the species in Brazilian and Argentine waters. The strategy adopted by the Argentina population involves a lower production of larger eggs compared to the population in Brazil; this lower production is associated with reproduction in cold‐water regions.  相似文献   

Aspects of the reproductive biology of skates (Chondrichthyes: Rajiformes: Rajoidei) from southern Africa     

Ebert  David A.; Compagno  Leonard J. V.; Cowley  Paul D. 《ICES Journal of Marine Science》2008,65(1):81-102

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厦门港中华哲水蚤卵型研究     

杨青  曹文清  林元烧  桂月  李少菁 《海洋学报》2007,29(5):117-122

对厦门港中华哲水蚤(Calanus sinicus)的卵型进行观察和研究,获得主要结果如下:(1)厦门港中华哲水蚤仅存在一种基本卵型,属于无鞘卵,但卵表面具有透明、柔软的胞膜(blister),胞膜呈褶皱结构;(2)胞膜可因外力而脱落,但胚胎仍可以正常发育;(3)在实验室水温为16~22℃条件下,受精卵均可正常孵化与发育;(4)胞膜的厚度有一定的变化,它随着水温的升高有减小的趋势.卵型分析与孵化实验均证实:厦门港中华哲水蚤不存在休眠卵(dormant egg)或滞育卵(diapause egg).  相似文献