ABSTRACT

Vertical burrowing is a biological activity deemed to have evolved during the earliest Cambrian, the older soft-bodied fossils of the Ediacaran Period, that thrived between 575 and 541 Ma, seemingly being restricted to occupying the seafloor/ocean interface. Yet at two levels within the pre-Ediacaran sequence of the Amadeus Basin, central Australia, are vertical tubular features that have previously been reported as possibly of biogenic origin: a suite of such tubes occurs within the Areyonga Formation, dated at about 700 Ma, while two other tubular structures occur within the older Heavitree Formation that is perhaps 970–950 million years old. Should these structures prove, on re-examination, to indeed have been biologically formed, then vertical burrowing initially evolved possibly as much as 435 million years earlier than previously believed and these features would make the Amadeus Basin an isolated crucible of, seemingly, two evolutionary trials of vertical burrowing, albeit trials that ultimately failed for reasons that are discussed. Additionally, the same two stratigraphic levels each contain another structure that was also initially described as of biogenic origin, one being a possible body-fossil.

摘要

垂直挖洞是一种被认为是在最早的寒武纪进化的生物活动，它是埃迪卡拉纪的较旧的软体化石，在 575 到 541 Ma 之间蓬勃发展，似乎仅限于占据海底/海洋界面。然而，在澳大利亚中部 Amadeus 盆地的前埃迪卡拉纪序列中的两个层次上，有垂直管状特征，以前据报道可能是生物起源的：一组此类管状结构出现在 Areyonga 组内，年代约为 700 Ma，而另外两个管状结构出现在可能有 970-9.5 亿年历史的较老的 Heavitree 组中。如果这些结构在重新检查时证明确实是生物形成的，然后垂直挖洞最初的进化可能比以前认为的早 4.35 亿年，这些特征将使阿马德乌斯盆地成为看似两个垂直挖洞进化试验的孤立坩埚，尽管试验最终因讨论的原因而失败。此外，相同的两个地层层均包含另一种结构，该结构最初也被描述为生物起源，其中一个可能是身体化石。