Comment on “Ophiomorpha irregulaire, Mesozoic trace fossil that is either well understood but rare in outcrop or poorly understood but common in core” by R.G. Bromley and G.K. Pedersen: [Palaeogeography, Palaeoclimatology, Palaeoecology 270 (2008) 295–298

Reliable identification of trace fossils in core is a significant challenge to applied ichnologists. Sedimentological models are commonly refined by the addition of ichnological datasets derived from core material. Unfortunately very few original descriptions and diagnoses of ichnological taxa include a full range of descriptions and cross sections to aid in core-based recognition. Ophiomorpha irregulaire is a case-in-point in that it is incompletely known in 3D from field specimens, and has become increasingly commonly recognised in core material based on pellet morphology. Recent work (Bromley & Pedersen 2008) has highlighted the fact that the meander maze of O. irregulaire cannot be seen in core due to a difference in scale of observation. This work highlights the need for a reassessment of pellet morphology in the type material, and makes direct comparisons of pellet morphology in O. irregulaire from the type area with material from other regions. We thereby consider that, contrary to earlier assertions, O. irregulaire is widely distributed in the Mesozoic, and reject palaeogeographic and stratigraphic criteria for restricting the use of the name to material from the Western Interior Seaway.