The first animals with teeth and back-bone
Conodonts have an excellent fossil record spanning 300 million years. Study of their feeding apparatus can give insight into the biology and function of the primitive vertebrate skeleton. The CONODONT (Decoding the conodont fossil record through analysis of function in ontogeny and phylogeny) project has used the changing features of the teeth and jaw to give a picture of the ecological dynamics of the era. Previous research had revealed that the growth and position of the teeth is different to that of jawed vertebrates. Moreover, they were too small and some not even anchored suggesting they couldn't be used effectively as teeth. The researchers developed high resolution models of the conodont clade, the oldest fish and all its descendants using the Swiss Light Source synchotron. Through finite element analysis and occlusal fingerprint analysis, they have derived the function of these elements. Results show that the conodonts' dental microstructure maximised resistance to load and differences between clades reflect variation in dietary preferences. When there were changes in teeth structure and arrangement, adaptive radiation was linked to changes in food niches. Wear and tear studies show evidence of repair suggesting that conodonts did not shed and regrow teeth. Dental comparison of successive types of conodonts could provide insight into the relationship between the first conodonts and the most advanced form that ever lived. Looking at the broader impact of the research, geochemists can compare seawater chemistry millions of years ago via chemical analysis of the conodont teeth. Evolutionary patterns, feeding ecology and environmental variations can all be then derived from seawater chemical content.
Keywords
Teeth, conodonts, vertebrate skeleton, food niche, seawater composition
