Why is intercontinental correlation within the Lower Cambrian so difficult?

Resumen

Correlation of Lower Cambrian rocks is hampered because there are no widespread and rapidly evolving organisms such as the later agnostids, graptolites, conodonts, ammonites, or planktonic foramini fers, that might provide the basis for a consistent intercontinental biostratigraphy. Four problems illustrate the issue: 1) the age of the oldest trilobites of China; 2) acritarch correlations between Siberia and Baltica; 3) conflicts between archaeocyath and trilobite correlations; and 4) the location of the Lower Cambrian/Middle Cambrian boundary. There is no basis for an internationally useful set of Lower Cambrian stages at this time.