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Shell from Transformations of the Carditidae

Carditidae 变形的壳

基本信息

批准号：
63540634
负责人：
MATSUKUMA Akihiko
金额：
$ 1.02万
依托单位：
National Science Museum
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

项目摘要

The mode of life of Carditidae (Mollusca : Bivalvia) may be either of the byssally attached epifaunal type (or upper tier burrower), in which case they have well-developed byssal threads, or of the free-living infaunal type, in which they have a very weak byssuses or completely lack them throughout all their life. Cyclocardia species with a subequilateral shell belong to the former and strongly inequilateral Cardita species with a prosogyrate beak to the latter. Anatomical and ecological studies of the Carditidae suggest that the byssally attached mode of life is more advanced than the free-living type (Yonge, 1969).Cartesian transformations are a simple deformation of from inscribed in a system of rectangular co-ordinates. If a drawing of Cyclocardia ventricosa within a system of Cartesian coordinates is transferred to a system, after compression in the y-direction, in which for the y of the original diagram substituting Y = 9y/10, a drawing which is a very is a very close approximati … More on to the shell form of C. spurca is obtained. C. turgida has a dorso-ventrally compressed shell, which is subject to a reduction of shell height corresponding to Y = 8y/10. Cartesian transformations seem to be applicable to compare related forms in a genus or in closely related genera of a subfamily.The "simple shear" is a deformation described in terms of the oblique axes X and Y. The Y axis is inclined to y axis at an angle rheta. If the drawing of C. ventricosa within a system of Cartesian co-ordinates is transferred to a system in which for the X=x+y^. tan 345^ﾟ and Y=y, a drawing which is a very close approximation to the shell form of Megacardita and Cardites species is obtained. If the original drawing within a system of Cartesian co-ordinates is transferred to a system of combination of the Cartesian deformation and the "simple shear", a drawing which is a very close aproximation to Megacardita turgida is obtained. The simple shear deformation and the combination of the Cartesian deformation and the "simple shear" may be applicable to compare shell forms of species belong to different subfamilies.The Thecaliinae species have a blood chamber at the ventral margin. The shell form is so peculiar that a close approximation is not obtained in terms of transformations of shell from. The result of shell form transformation suggests that the Thecaliinae is most specialized group within the Carditidae. This is also supported by the paleontological evidence that the Thecaliinae species are only known as living forms. Less

Carditidae（软体动物：双壳纲）的生活方式可以是足丝附着的表层动物类型（或上层穴居动物），在这种情况下，它们具有发达的足丝，也可以是自由生活的内动物类型，在这种情况下，它们的足丝非常薄弱，或者一生中完全没有足丝。具有近等边壳的 Cyclocardia 物种属于前者，而具有前旋喙的强不等边 Cardita 物种属于后者。对 Carditidae 的解剖学和生态学研究表明，附生的生活方式比自由生活的类型更先进（Yonge，1969）。笛卡尔变换是内切于直角坐标系的简单变形。如果将笛卡尔坐标系内的 Cyclocardia ventricosa 绘图转移到系统中，在 y 方向压缩后，将原始图的 y 替换为 Y = 9y/10，则获得非常接近 C. spurca 壳形式的绘图。 C. turgida 有一个背腹压缩的壳，其壳高度会减少，相当于 Y = 8y/10。笛卡尔变换似乎适用于比较一个属或亚科密切相关属中的相关形式。“简单剪切”是根据斜轴 X 和 Y 描述的变形。Y 轴以一定角度 rheta 倾斜于 y 轴。如果将笛卡尔坐标系内的 C. ventricosa 绘图转移到 X=x+y^ 的系统中。 tan 345^ﾟ和 Y=y，获得了非常接近 Megacardita 和 Cardites 物种的壳形式的绘图。如果将笛卡尔坐标系内的原始绘图转移到笛卡尔变形和“简单剪切”组合的系统中，则会获得非常接近 Megacardita turgida 的绘图。简单剪切变形以及笛卡尔变形与“简单剪切”的结合可用于比较不同亚科物种的壳形态。 Thecaliinae物种的腹侧边缘有一个血室。壳的形式非常特殊，以至于在壳的变换方面无法获得紧密的近似。壳形态转变的结果表明，Thecaliinae 是 Carditidae 中最专业的类群。古生物学证据也支持了这一点，即 Thecaliinae 物种仅被视为活着的形式。较少的