The project addresses key aspects of macroevolution, the large-scale evolution of life as measured on geological time scales of millions of years. These key questions explore how morphology, the external appearance of organisms, evolves and why some groups such as birds become so successful, when their closest relatives, crocodiles, did not? Further, to what extent do successful groups like birds owe their success to remarkable innovations (flight, feathers) or to changing environmental circumstances, including external crises?
We explore these questions using the fossil record of tetrapods, the amphibians, reptiles, birds and mammals. There are 30,000 living species of tetrapods, and they have a rich fossil record spanning some 400 million years. Further, the phylogenetic tree of living and fossil tetrapods is relatively well understood, and with dates from key fossils, we can draw a reasonably reliable time tree. This is a phylogenetic tree, showing the relationships of species, but with key branching points reasonably reliably dated. Methods now exist to analyse patterns and rates of evolution across such time trees, with proper expression of multiple uncertainties (relationships, dating, incompleteness of the fossil record). Knowing when rates of evolution accelerated points to times of expansion that can be matched to external environmental events or the emergence of particular functional novelties.
The first aim of the ‘Innovation’ project was to produce a complete phylogenetic tree of tetrapods (30,000 living species; 10,000 extinct species) and use this to explore a core question in macroevolution: are three outputs: (1) the complete evolutionary tree of tetrapods; (2) a table of morphological characters across all tetrapod groups; and (3) many case studies of macroevolution among tetrapods (e.g. amphibians, early reptiles, dinosaurs, birds, mammals) in leading scientific journals. In sum, these will provide the largest-ever geologically dated morphological evolutionary tree and character set, so enabling a thorough exploration of key evolutionary drivers and models across a single important clade.
