I have studied dental and dermal skeletal diversity in early vertebrate fossils from all localities in the world with a focus on the evolution of dentitions and their pattern of change within phylogenies to suggest a developmental model for patterning the dentition. This proposes separate modules for teeth and jaws in development and in evolution and predicts important stages in the evolution of regulatory genes during changes to the vertebrate dentition.
I have specialised in the dentition with a unique research career spanning two separate fields of study, developmental biology and palaeontology and am an international expert in the evolution and diversification of vertebrate skeletal tissues. Recently, the Leverhulme Emeritus Fellowship and my links with the Graham lab have allowed studies in molecular developmental biology to progress with four recent publications.
My most extensive contribution has been to the field of vertebrate skeletal origins and the evolution of jaws and teeth since 1966, through an understanding of the biodiversity of extant and fossil dento-skeletal tissues. I have proposed developmental models to explain this diversity and the evolution of teeth and jaws with a challenge to two classic canonical views. The first, involving neural crest as the fourth embryonic germ layer proposed that post-cranial neural crest was also skeletogenic in non-amniote vertebrates with a study of urodele tooth development and one on the fish caudal fin skeleton. The second, concerns the significance of oral denticles to the evolution of teeth, with a proposal to reverse the old ideas and suggest that pharyngeal denticles are the source of patterning for tooth sets on the jaws and these rather than skin ”teeth” are co-opted for the jaw teeth.
This suggestion promotes the idea that endoderm is the key embryonic layer for patterning the dentition and not ectoderm. With the Graham lab we will continue to search for marker genes for tooth induction, in patterning the dentition in basal vertebrates and the probable role of the dental lamina in this process.
My studies with colleagues in Australia and France of the exclusively fossil group at the base of jawed vertebrates (placoderms) has allowed us to propose that teeth are present but are convergently derived within the group. We have suggested that this further supports the independence of the development and evolution of teeth from jaws.