陕南早寒武世早期磷酸盐化Punctatus奇异星状口盘的发现及其形态功能分析

早寒武世最早期梅树村期处于“寒武纪大爆发”序幕阶段。在这一时期,生物类群发生了大规模辐射演化及其身体构型的快速革新,形成与前寒武纪生物群明显不同的生物组合面貌。最近在陕南宽川铺地区早寒武世早期灯影组宽川铺段地层中发现了数十枚呈三维立体精美保存的磷酸盐化奇异星状生物化石标本,通过形态功能分析及与其共生的Punctatus的口盘类比表明,该奇异星状生物很可能属于腔肠动物Punctatus的口盘,星状体的中心为该生物的口部。而腔肠动物的出现标志着真后生动物的开始,在生物起源演化历程上占据着极其关键的位置。本文报道的奇异星状生物可能代表了初具原始触手的腔肠动物早期演化类型,为研究真后生动物起源演化、功能进化提供了新的实证材料。

PHOSPHATIZED STAR-LIKE ORAL DISC OF PUNCTATUS AND ITS FUNCTIONAL MORPHOLOGY FROM EARLY EARLY CAMBRIAN OF SOUTH SHAANXI

The Meishucun stage is the prelude of the Cambrian Explosion. In this prominent stage, rapidly radiating evolution and body-plan innovation took place and different associations of organisms formed. In this paper, several 3D-preserved bizarre star-like fossils with finely preserved soft tissues are reported which were recovered from the Kuanchuanpu Member of the Dengying Formation in South Shaanxi, China in 2003. By functional morphology and analogy with mouthpart of Punctatus, it is shown that this star-like organism resembles the coelenterate in systematic classification with the mouth situated at the centre of the star-like organism. The appearance of coelenterate marks the real beginning of metazoan evolution. Therefore, it has the prominent position in the origin and evolutionary history of organisms. Perhaps the star-like organism represents the early types of coelenterate with original tentacles. These new materials provide new evidence for the origin, evolution and the functional evolution of the metazoan during the early stage of the Cambrian explosion.