Rare fossilised prehistoric Hexanchus comb shark tooth exhibiting good morphology and preservation, the delicate tooth intact with an attractive toffee colour enamel, repair to the midsection of the root where re-fixing the tooth has taken place. Often these small shark teeth suffer damage in the fossil bed and on excavation requiring conservation work including cleaning off any attached matrix (fine fossil bed sand grains) and re-fixing where necessary. The typical tooth is recognised by the comb like-structure of the apical crowns. Each cusplet form the triangular apical point. The medial cusplet being the largest is typified with finer serrations along the leading edge. These are referred to as coarse serrations.
The species Hexanchus agassizi, described by Cappetta, 1976, first appeared in the late Cretaceous period around 100 million years ago. While N. cepedianus, Notorynchus, described by Ayres, 1855 appears around the late Paleocene 60 million years ago. The cow shark tooth here was discovered in Morocco in North Africa. Refer to the above link in our short distribution for topographical information on the fossil bed in Morocco. The range of the six-gill sharks was then and still is today, worldwide.
The ancestors of the prehistoric six-gill sharks persist in today's oceans, the deepwater sharks belong to the family Hexanchidae. Characterised by a broad, pointed head, six pairs of gill slits, comb-like yellow lower teeth, and long tails. Six-gill sharks attain sizes of up to 8 metres in length, weighing over 600 kg (1320 lb.). Being abyssal plain scavengers with a keen sense of smell they can be found among the first predators to arrive at carrion and have been found at depths to 2,500 ft (760 m).