Completeness of the fossil record and the validity of sampling proxies: a case study from the Triassic of England and Wales

Many studies have highlighted correlations between palaeodiversity and sampling proxies. These correlations have been interpreted as evidence for bias, common cause, or redundancy between signals. Here, we compare a number of sampling proxies representing sedimentary rock volume, rock accessibility and worker effort with palaeodiversity through the predominantly terrestrial Triassic System in England and Wales. We find that proxies for sedimentary rock volume and accessibility do not correlate with palaeodiversity until the removal of facies-related preservational and palaeoecological factors. This indicates that a weak sampling signal may be present, but the effects of changing palaeoenvironments are far more important at the regional scale. Significant correlations between worker effort and palaeodiversity are detected, although this is likely to be a result of the preferential sampling of formations already known to be rich in fossils. The fact that there is little evidence for sedimentary rock bias in the fossil record of the Triassic of England and Wales suggests that either (1) sampling bias is not a major source of error at the regional scale or (2) sampling proxies are inadequate representations of geological and human sampling bias.