Burrowing below the basal cambrian GSSP, Fortune Head, Newfoundland

The range of Treptichnus: the index trace fossil for the Treptrichnus pedum Zone, extends some 4 m below the Global Standard Stratotype-section and Point for the base of the Cambrian Period at Fortune Head on the Burin Peninsula in southeastern Newfoundland. The identification of zigzag traces of Treptichnus isp. even further below the GSSP than T. pedum in the Fortune Head section, and in Ether terminal Proterozoic successions around the globe, supports the concept of a gradational onset of three-dimensional bur rowing across the Proterozoic-Cambrian boundary Although T. pedum remains a reasonable indicator for the base of the Cambrian Period, greater precision in the stratotype section can be achieved by a detailed re-evaluation of the stratigraphic ranges and the morphological variation of ichnotaxa included in the T. pedum Zone.