Does a taxonomic identification bias affect diversity analyses on dinosaurs?

The fossil record is not a faithful chronicle of the history of past life, but is instead beset by sampling and preservational biases that need to be accounted for if we are to understand biodiversity patterns in the past. Although many biases are well understood, and can be corrected for using a variety of statistical procedures, one which has not previously been investigated is a taxonomic identification bias.

The taxonomic identification bias arises from the potential for some taxa to be more readily identified because the bones on which their diagnostic characteristics are found are more likely to be preserved. This is important, because if a taxon can be identified, it is more likely to be described in the scientific literature and thus included in large databases, such as the Palaeobiology Database from which many biodiversity studies derive their data.

The objectives of this research are:

>To list diagnostic characteristics of Morrison meat-eating dinosaur genera;
>To generate a ‘likelihood of preservation’ metric for each bone in the dinosaur skeleton based on the literature of fossil preservation;
>To score each genus based on how likely its bones are to be preserved;
>To statistically examine relationships between likelihood of preservation and abundance in the Morrison Formation.

The aim of this study is to investigate whether a taxonomic identification bias is present among meat-eating dinosaurs in the Upper Jurassic Morrison Formation, western USA. The Morrison Formation is a sequence of rocks deposited by rivers and on flood plains 155-145 million years ago. The formation has received much attention since the discovery of its diverse and well-preserved dinosaurian fauna in the latter part of the nineteenth century. Eleven meat-eating dinosaurs are currently recognised from the Morrison, but the well-known taxon Allosaurus is by far the most abundant, comprising 66% of reported finds. In this project, we test the hypothesis that the high abundance of Allosaurus is because it is more easily identified than other Morrison theropod taxa, since its diagnostic characteristics occur on bones more likely to be preserved.