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Sharks are covered with thousands of dermal denticles (shown here in green/red) that are remarkably similar to their awe-inspiring teeth. The denticles are precisely arranged over the skin surface to allow the sharks to swim efficiently and silently through the water. Combining 3D image analysis with molecular genetic analyses during development, scientists can test hypotheses about the evolutionary origins of teeth in vertebrates. It is now known that all vertebrates use similar dental genes to develop teeth, and those genes are highly conserved over some 450 million years from sharks to mammals.
The catshark head was scanned using X-ray microscopy (XRM) and subsequent 3D computer reconstruction. Scanning was performed at the Imaging and Analysis Centre, Natural History Museum, London with thanks to Amin Garbout PhD, and Farah Ahmed PhD and Brett Clark for 3D rendering assistance.
Gareth J. Fraser PhD, Kyle J. Martin PhD, Department of Animal and Plant Sciences, University of Sheffield, U.K.; Zerina Johanson PhD, Department of Earth Sciences, Natural History Museum, London, U.K.