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早寒武世双壳类Pojetaia runnegari内模上的肌痕有助于证实P.A.Jell提出的见解,即P.runnegari与奥陶纪古栉齿类有密切联系。Pojetaia与奥陶纪古栉齿类不同,并经常把它与仅有的另一已知的寒武纪双壳类Fordilla合为一类的特征,这或许是由于它们的个体很小(约1毫米)引起的。自从Pojetaia归于古栉齿类栗蛤目的前栗蛤科及Fordilla似乎是瓢形蛤类的壳菜蛤类以后,早先提出的包括Fordilla,而后又扩大包括Pojetaia的双壳类Fordilloida目就不再使用。Pojetaia和Fordilla两者有长久的地层时代分布:Pojetaia从托莫特阶(Tommotian)到早寒武世末;Fordilla大致从阿特达班阶(Atdabanian)早期到早寒武世晚期。 Pojetaia是北半球的热带动物,穴居于碳酸盐软泥中,似乎是“入水孔食泥动物”。大概在不到一年时间内,逐渐长成1.2毫米的平均大小,它们幼虫的发育象是蛋黄营养的,但不是直接的。虽然从酸残余中找到只具有外部和内部壳表的磷酸盐质复型(replica),但有充分证据说明Pojetaia有被表壳层覆盖的由单层球粒的柱状文石组成的壳。从各方面看,Pojetaia是一个非常原始的软体动物。它和Fordilla是大多数已知双壳炎较高级分类单位合适的祖先。
Muscle marks on the inner mold of the early Cambrian Bivalvia, Pojetaia runnegari, help confirm the assertion by P.A. Jell that P. runegnegari is closely related to the ancient Ordovician teeth. Pojetaia differs from the Ordovician Paracarps and often combines it with only the other known Cambrian bivalve Fordilla, perhaps due to their small size (about 1 mm) caused. Since Pojetaia was due to the ancient chestnut-like clam clam and the chestnut clam that Fordilla appeared to be scoop-shaped clams, the previously proposed Fordilloida, including the Fordilla, which later expanded to include the Pojetaia bivalve, was no longer used . Both Pojetaia and Fordilla have long stratigraphic epochs: Pojetaia from the Tommotian to the end of the Early Cambrian; Fordilla roughly from the early Atdabanian to the late Early Cambrian. Pojetaia, a tropical animal in the northern hemisphere, hangs in carbonate slime and appears to be “water hole muddy animal.” In less than a year, it gradually grew to an average size of 1.2 millimeters and their larval development was like egg yolk nutrition, but not straightforward. Although the phosphate replica with only the outer and inner shells is found from the acid leftover, there is good evidence that Pojetaia has a shell composed of a single-layered, spherical columnar aragonite covered by the shell. In all respects, Pojetaia is a very primitive mollusc. It is a suitable ancestor of Fordilla, the more advanced taxa of known bivalveitis.