Regional differentiation of felid vertebral column evolution: a study of 3D shape trajectories

Recent advances in geometric morphometrics provide improved techniques for extraction of biological information from shape and have greatly contributed to the study of ecomorphology and morphological evolution. However, the vertebral column remains an under-studied structure due in part to a concentration on skull and limb research, but most importantly because of the difficulties in analysing the shape of a structure composed of multiple articulating discrete units (i.e. vertebrae). Here, we have applied a variety of geometric morphometric analyses to three-dimensional landmarks collected on 19 presacral vertebrae to investigate the influence of potential ecological and functional drivers, such as size, locomotion and prey size specialisation, on regional morphology of the vertebral column in the mammalian family Felidae. In particular, we have here provided a novel application of a method—phenotypic trajectory analysis (PTA)—that allows for shape analysis of a contiguous sequence of vertebrae as functionally linked osteological structures. Our results showed that ecological factors influence the shape of the vertebral column heterogeneously and that distinct vertebral sections may be under different selection pressures. While anterior presacral vertebrae may either have evolved under stronger phylogenetic constraints or are ecologically conservative, posterior presacral vertebrae, specifically in the post-T10 region, show significant differentiation among ecomorphs. Additionally, our PTA results demonstrated that functional vertebral regions differ among felid ecomorphs mainly in the relative covariation of vertebral shape variables (i.e. direction of trajectories, rather than in trajectory size) and, therefore, that ecological divergence among felid species is reflected by morphological changes in vertebral column shape

Earth's deep history : how it was discovered and why it matters

Earth has been witness to mammoths and dinosaurs, global ice ages, continents colliding or splitting apart, comets and asteroids crashing catastrophically to the surface, as well as the birth of humans who are curious to understand it all. But how was it discovered? How was the evidence for it collected and interpreted? And what kinds of people have sought to reconstruct this past that no human witnessed or recorded? In this sweeping and magisterial book, Martin J. S. Rudwick, the premier historian of the earth sciences, tells the gripping human story of the gradual realization that the Earth�s history has not only been unimaginably long but also astonishingly eventful