Paleobiogeographical variation of Cretaceous <i>Mecaster batnensis</i> and <i>Mecaster fourneli</i> (Echinoidea: Spatangoida)

Spatangoids are the echinoid group best represented in the South American Cretaceous fossil record. This study analyzed two Cretaceous spatangoid species of the genus Mecaster (M. batnensis (Coquand, 1862) and M. fourneli (Agassiz, 1847)) found in South America as well as Africa, North America, Asia and possibly Europe (Smith and Bengtson 1991, Smithsonian Collection). This study assessed the paleobiogeographical variation of these species. Specimens from at least eight widely spaced localities were measured for morphometric analysis. Initial observations using length, width, and height data of M. batnensis and M. fourneli populations indicate regional differences in growth trajectories. A comparative morphometric analysis including traditional two-dimensional measurements using calipers and three-dimensional landmark measurements obtained with a laser scanner was performed. Principal component analysis and other multivariate methods identified the extent of variation between localities.