This page serves supplemental imagery for a paper entitled The oldest North American pachycephalosaurid and the hidden diversity of small-bodied ornithischian dinosaurs, by D.C. Evans, R.K. Schott, D.W. Larson, C.M. Brown and M.J. Ryan (2013, Nature Communications, 4:1828). The abstract is as follows:

Taphonomic biases dictate how organisms are represented in the fossil record, but their effect on studies of vertebrate diversity dynamics is poorly studied. In contrast to the high diversity and abundance of small-bodied animals in extant ecosystems, small-bodied dinosaurs are less common than their large-bodied counterparts, but it is unclear whether this reflects unique properties of dinosaurian ecosystems or relates to taphonomic biases. A new, fully domed pachycephalosaurid dinosaur, Acrotholus audeti, from the Santonian of Alberta predates incompletely domed taxa, and provides important new information on pachycephalosaur evolution and the completeness of the ornithischian fossil record. Here we provide the first empirical evidence that the diversity of small-bodied ornithischian dinosaurs is strongly underestimated based on ghost lineages and the high proportion of robust and diagnostic frontoparietal domes compared with other pachycephalosaur fossils. This suggests preservational biases have a confounding role in attempts to decipher vertebrate paleoecology and diversity dynamics through the Mesozoic.

Click here to download the original 16bit dataset (416 Mb).

This specimen, the holotype, was collected from the Deadhorse Coulee Member of the Milk River Formation (Late Santonian), southern Alberta, Canada. It was made available to the University of Texas High-Resolution X-ray CT Facility for scanning by Dr. David Evans of the Royal Ontario Museum. Funding was provided by Dr. Evans.

This specimen was scanned by Matthew Colbert on 13 August 2012 along the horizontal axis for a total of 292 slices. Each 1024 x 1024 pixel slice is 0.25 mm thick with an interslice spacing of 0.23 mm (resulting in a slice overlap of 0.02 mm), and a field of reconstruction of 121 mm.

Literature

Evand, D.C., Schott, R.K., Larson, D.W., Brown, C.M., and Ryan, M.J. 2013. The oldest North American pachycephalosaurid and the hidden diversity of small-bodied ornithischian dinosaurs. Nature.