A cautionary note on the use of invertebrate trace fossils for correlation in the Triassic-Jurassic Fundy Group

摘要

Red-bed strata generally considered to be of Triassic age are present in outcrop at Point Lepreau and St. Martins, New Brunswick. These successions preserve assemblages of invertebrate trace fossils that are similar to one another. Some authors have taken this as evidence that the successions are of similar age. However, all ichnotaxa that are common to the two successions (Ancorichnus cf. ancorichnus, Gordia marina, Palaeophycus isp., Planolites isp., and Skolithos isp.) are long-ranging forms that provide no useful age constraints in Triassic strata and cannot support the suggested correlation. Similarities between the ichnofaunas reflect the continental depositional setting of the two successions, in which trace-makers produced a Scoyenia ichnofacies. This does not falsify correlation between the Point Lepreau and St. Martins successions, which can be supported on other grounds. Instead, it reinforces the need for caution when using trace fossils for biostratigraphic purposes in much of the stratigraphic record.