Turtle macroevolution: contributions from quantitative, virtual paleontology, and biomechanical analyses

Abstract

This project aims to characterize and explore the macroevolutionary patterns of Testudinata (turtles, tortoises and terrapins), a reptile group with a long evolutionary history (cc. 220 myrs.), a rich fossil record and a (relatively) great taxonomic and ecomorphologic diversity, both for extant and extinct taxa. As general objectives, the project intends to explore the morphological evolution of the group, focusing on evolutionary novelties of Pleurodira, and to test if the patterns of species diversification and morphological disparity support the characterization of turtle's evolutionary history from the Jurassic as an adaptive radiation. For such, two complementary lines of research are proposed. The first aims to use advanced tomographic imaging techniques (such as augmented laminography and neutron computed tomography) to reconstruct digital models of the most complete specimens of Platychelys oberndorferi (Jurassic, Germany), the only stem-Pleurodira with preserved skull and complete cervical vertebrae series, and two specimens of Araripemys barretoi (Cretaceous, Brazil). These models will be employed in morphological, phylogenetic and functional/biomechanical (FEA) analyses with the goal of assessing the influence of a knowledge increase about the earliest Pan-Pleurodira on the phylogenetic relationships of all turtle groups and also between neck flexibility and skull morphology in the group. The second research line aims to identify and characterize the macroevolutionary patterns of speciation/extinction (diversification) rates, using a phylogenetic approach that includes data on the fossil record (BAMM), and rates of morphological disparity change, using a discrete character morphospace approach (PcoA). The use of advanced techniques of quantitative and biomechanical analyses and of virtual paleontology to address macroevolutionary questions in turtles represents a still incipient conceptual and methodological innovation in the context of Brazilian Paleontology.