The Mitsukurinids are represented today by the elusive deepwater Goblin Sharks, known for their protruding jaws. The group are well represented in the Chalk, though the taxonomy is confused, with Scapanorhychus likely polyphyletic (containing forms which are not closely related) and a difficulty distinguishing some latero-posterior forms from the Odontaspids.
The relatively large, tearing anterior teeth are most easily recognised, bearing very tall and highly slender main cusps, lacking accessory cusps, and often with fine vertical striations on the lingual face of the crown. There is a lingual protrusion, typically bearing a nutritive cleft (a deep vertical groove through the lingual apex), and long, pointed root halves. The latero-posterior teeth differ, possessing pointed accessory cusps, well separated from the main cusp, and more rounded root halves.
1). (A) Anomotodon sp. - Labial view of an anterior tooth (x3.7, Booth Museum, BMB 024342, by kind permission of John Cooper); (B, C) Scapanorhynchus raphiodon - (A) Labial and (B) side views of an anterior tooth lacking root. Note the smooth labial surface and the characteristic fine striations on the lingual surface (x4.4, 'Middle' Chalk, Lewes, Willett Collection, Booth Museum, BMB 007314, by kind permission of John Cooper).
2). Scapanorhynchus raphiodon - (A) Labial, (B) side and (C) lingual views of an anterior tooth lacking root. Note the smooth labial surface and the characteristic fine striations on the lingual surface (x4.8, Booth Museum, by kind permission of John Cooper).
3). Paranomotodon angustidens - (A) Lingual and (B, C) labial views of antero-lateral teeth (A) x4.5, B) x5.5, C)x5.5, Grey Chalk, Lewes, Sussex, NHMUK (British Museum (Natural History) London) PV P14218-14233). Images © 2012 The Natural History Museum, by kind permission.
4). Mitsukurina owstoni, the extant Goblin shark - rare imagery of live individuals: (A) General view (view footage on You Tube); (B) Close up of the head with jaws extended to seize prey (view footage on You Tube) Images are still frames from footage on You Tube.