Pre Cambrian Boundary Essay

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Throughout the last 30 years there have been changing perceptions of the pre-Cambrian to Cambrian boundary in scientific circles. However the same questions arise, most notably, just where, stratigraphically, is the boundary? The four chronological articles which have been discussed here spanning from 1987 to 1998 show shifting in the paradigm of thinking and analysis, of this time in earth’s history, as scientific techniques have improved and new fossil evidence has come to light. The explosive radiation of metazoans into the extensive geological niches that existed in the early Cambrian may seem abrupt in the fossil record but in actual fact spanned many years. The fossil record during the Precambrian was dominated by stromatolites. Sedimentary…show more content…
This holistic approach takes into account major environmental factors, which either affect the developing metazoans themselves, or the process which preserved them. During the late pre-Cambrian there appears to have been a transgression in sea level, rapid continental break up facilitated by tectonics, causing rifting and rapid sea level rise would have had severe biological implications. This limits the ability to define a boundary stage, as the geological events occurring were not useful for the preservation of a continuous fossil record. As this sea level transgression occurred, the habitable area available to developing marine metazoans expanded, coupled with continental break up hindering migration, the rise of endemic faunas exploded. (Conway Morris 1987). Geochemical events such as potential asteroid impacts are also discussed in this paper, and their likely effect of disrupting ecological systems, which may have led to mass extinctions. Conway Morris discusses the implications of this, such as the idea that a drop in oceanic productivity after an asteroid impact “opened the ecological gates to the Cambrian explosion”. This paper broadly covers the modes of thinking about the boundary transition around the 1980s, and the many different and applicable theories as to its characteristic fossil

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