Funded by the Natural Environment Research Council, the three-year project could give researchers a new insight into the evolution and development of teeth and their arrangement in the mouth – called dentition. It may also reveal why humans and mammals only develop one or two sets of teeth in their lifetime, compared to their ancestors, the bony fish, which constantly regenerate their teeth.
Every jawed vertebrate needs teeth to function and feed. But exactly how teeth evolved is poorly understood, because it is difficult to interpret different stages of tooth development from fossils.
Lead researcher Professor Moya Meredith Smith, Dental Institute at King’s, said: ‘We still don’t have a clear understanding of how dentitions are built. To understand dentition patterns you need to look at animals that build their teeth on a regular basis, like fish.’
The team, co-ordinated by Dr Zerina Johanson of the Natural History Museum, plan to look at the development of different teeth arrangements in modern day vertebrates and then apply their findings to fossils from the same group.
Jawed vertebrates evolved into several different types of animal and fish, but there are only two major groups, which are still living today. One is sharks, or Chondrichthyes; while the other is Osteichthyes, or bony fish.
‘Bony fish eventually evolved into mammals, like humans. But to define how the teeth evolved we don’t want to look at dentitions in mammals like mice. Instead, if you want to define how dentition evolved you need to look at more primitive members of groups,’ explains Dr Johanson.
The project will look at modern day Chondrichthyans, such as sharks and rays, to give them an insight into how the teeth from both these groups evolved.
While much is known about the dentition of modern day Osteichthyans, like tuna, salmon or seahorses, little is known about their early ancestors.
Professor Smith, Dr Johanson and their colleagues hope to change this when they compare their findings about Chondrichthyans to fossil specimens of early Osteichthyans. They hope to discover whether the two groups share a common dentition or whether the teeth in the cartilaginous sharks and rays evolved very differently to the boned fish.
Dr Johanson added: ‘You can’t regenerate teeth but people are now starting to look more seriously at how certain fish regenerate teeth and some bony fish continually regenerate (although sharks do it more regularly). If we can understand what cells and genes are involved in regeneration of shark teeth then maybe we can look at teeth in humans and see comparable genes that can be used to regenerate teeth. But that is still very much in the distant future.’
Image credit: Zerina Johanson, Moya Meredith Smith & Charlie Underwood.
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