The Marie S. Curie Actions Project “JurRad” focuses on the evolution of the major group of theropod dinosaurs: Averostra. However, despite being one of the most studied groups, it is also one of the most debated within theropods due to the unclear phylogenetic interrelationship of its ‘basal’ members and the relationships between their major clades. Averostra radiated explosively from the Early to Late Jurassic (from 182.7-145 million years), with the Pliensbachian-Toarcian extinction event (182 million years ago) probably being one of the major causes for this explosive evolution. The increase in the rate of morphological change that followed the extinction, together with the fragmentary nature of the fossil record of the ‘basal’ members could be the cause of the difficulties in unraveling the interrelationships among Averostra. The main goal of this research is to obtain a robust and synthetic view of the evolutionary drivers of this radiation of Averostra during the Jurassic, to explore when averostrans originated at the latest and unravel the impact of the previous extinction on their radiation and how the different lineages were established in the aftermath. To achieve this goal, it will carry out phylogenetical analyses of this group, the subsequent assessment of the morphological changes within a phylogenetic context in the early evolution of Averostra, and the evaluation of its connection with the Pliensbachian-Toarcian extinction event and consequent radiation of theropods. Moreover, it will be studied in detail the most complete early members of the two main averostran lineages, Eoabelisaurus mefi and Asfaltovenator vialidadi (Early Jurassic species) from the Patagonia of Argentina (Chubut province). These taxa are exceptionally complete and show unique character combinations, which will be essential for unravelling the role of the radiation in the early diversification of Averostra.
The specific objectives of the project are:
Specific Objective 1: To establish a good sampling of basal members of different clades within Averostra, gathering all the data available about Averostra taxa. Related to Work Package 1: Gathering of the taxa information and osteological data of Averostra taxa in order to have a good sampling of basal members of Averostra.
Specific Objective 2: To perform an exhaustive and detailed osteological description of two of the most complete and representative taxa from the Jurassic Cañadón Asfalto Formation in order to establish the phylogenetical context of these taxa and test for what the character combination seen in these taxa are key to understand about character distribution and morphological evolution in early averostrans. Related to Work package 2: Describing in-depth the osteology of two averostran taxa from the Cañadon Asfalto Formation.
Specific Objective 3: To produce a phylogenetic tree of Theropoda, focusing on the averostran relationships. Related to Work Package 3: Revision of previous analyses and elaboration of a new matrix of morphological characters in order to perform a heuristic and Bayesian search of phylogenetic trees.
Specific Objective 4: To explore the evolution of osteological traits and the evolutionary history of Averostra, analysing the morphological changes within a phylogenetic context, and, posteriorly, evaluate the likely causes of these changes in the early evolution of Averostra and its connection with the Pliensbachian-Toarcian extinction event and consequent radiation of theropods. Related to WP4: Evaluation of the effects of Pliensbachian-Toarcian extinction event in the radiation of Averostra, focusing specially in the effects of the homoplasy in the phylogenetical results.
