Flowers and the rise of mammals
Mammals and dinosaurs evolved around the same time, yet dinosaurs dominated the Earth for 200 million years while mammals remained small and innocuous. The conventional explanation is that the presence of dinosaurs suppressed mammalian evolution, through predation and competition for niches. The EU-funded MDKPAD (The radiation of modern mammals: Release from dinosaur incumbency or response to environmental change?) project tested a different theory. The alternative concerned the rise of angiosperms, also called flowering plants, during the final 10 million years of the dinosaurs’ reign. Angiosperms then had started forming their own microhabitats, resulting in a modern vegetation habit complexity that is associated with mammalian dominance. Researchers investigated the possibility that the change in angiosperm habitat complexity, and not the demise of the dinosaurs, led to the rise of mammals. To explore the theory, researchers ascertained whether mammal behaviour changed along with the changing habitats. The key question was whether the vegetational changes were linked to mammals changing from being primarily ground-dwelling to mainly arboreal. The data needed to answer the question came from anatomical examination of the fossil skeletons of late-Cretaceous mammals. Researchers photographed the anatomy of living mammals of known behaviour, and the relevant fossil anatomy: specifically joints. Statistical analysis of 84 mammal groups showed that anatomy does reflect behaviour. The selected groups could be sorted into terrestrial, semi-arboreal and arboreal locomotion with reasonable certainty. Late-Cretaceous and early Cenozoic (post-dinosaur era) mammals were mostly generalised and semi-arboreal. Yet, a few species specialised for arboreal life evolved during the final 10 million years of the Cretaceous. The results correspond to those from other researchers showing changes in dietary preferences. Both skeletal and dental data show an ecological transition, correlated with the floral changes. Other work involved researchers interacting with European colleagues, and students, to transfer knowledge. Researchers supervised senior undergraduate and postgraduate students, while also conducting formal and informal teaching. MDKPAD work demonstrated changes in a few late-Cretaceous mammals, apparently correlated with changes to vegetation complexity. Whether the correlation explains the post-dinosaur rise of mammals remains to be confirmed.
Keywords
Mammals, dinosaur, vegetation changes, habitat complexity, MDKPAD, angiosperms
