• There are three lithofacies in the Bowden Formation. The Bowden Shell Bed comprises the conglomerate/sandstone facies. Most conglomerate and calcareous siliciclastic/bioclastic sandstone layers exhibit evidence of deposition from sediment gravity flows. The presence of tractional features in several units and erosional bases in several others suggests deposition from high density, decelerating turbidity currents. No layers exhibit evidence of reworking by either fair weather or storm wave activity, suggesting that they were deposited in relatively deep water below storm wave base (>100 m). This would signify a submarine fan depositional environment. (Pickerill et al., 1998).

• The fossils were found in unit 2 of the 4-unit Bowden Shell Formation. The Bowden Shell Formation is itself one of the three lithofacies of the whole formation (conglomerate/sandstone facies). Clasts in the conglomerate layers comprise variably-sized shells, mainly molluscs, and sporadically distributed, well-rounded lithic pebbles and cobbles ranging up to 12 cm in diameter. The latter are of variable composition, and include siltstone, rhyolite, basalt and andesite; smaller pebbles also include quartz and chert (Palmer, 1945). Sorting is extremely poor. Shells are typically highly leached, and may be complete, broken, articulated or disarticulated and exhibit considerable size variation for individual species. Disarticulated valves of bivalve molluscs are preserved in all orientations from bedding parallel (both concave up and concave down) to perpendicular to bedding. Some of the larger, disarticulated valves are complete, but shattered by a pattern of cross-cutting fractures. Articulated shells may be 'empty', that is, not infilled by sediment. Carbonized wood fragments are also common. The conglomerate matrix comprises medium- to coarse-grained calcareous sandstone that is composed of bioclastic and siliciclastic grains of similar composition to the clast component. The internal texture of single conglomerate layers is heterogeneous with matrix- and clast-supported fabrics being variably developed both vertically and laterally. (Palmer, 1945; Pickerill et al., 1998).