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 Po int for the base of the Cambrian Period at Fortune Head on the Burin Penins ula in southeastern Newfoundland. The identification of zigzag traces of Tr eptichnus isp. even further below the GSSP than T. pedum in the Fortune Hea d 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 reaso nable indicator for the base of the Cambrian Period, greater precision in t he stratotype section can be achieved by a detailed re-evaluation of the st ratigraphic ranges and the morphological variation of ichnotaxa included in the T. pedum Zone.