Pachycostasaurus

Pachycostasaurus (meaning 'thick-ribbed lizard') is an extinct Pliosauroid from the Oxford Clay formation of Peterborough, England.

==History and naming== The holotype fossil of Pachycostasaurus was discovered by Alan Dawn, an amateur geologist and museum volunteer, in what is now a quarry in Peterborough. The fossil was described in 1996 by Palaeontologists Arthur Cruickshank, David Martill and Leslie Noè, due to its distinct set of features not present in contemporary pliosaurids Liopleurodon and Simolestes.