Although only named in 1996 this animal has been known since 1838, when Owen gave it the name Plesiosaurus hawkittsii. It was part of the extensive marine fauna found by Thomas Hawkins, the noted Victorian collector of fossil sea animals, in Somerset, southwest England. There is some disagreement between palaeontologists as to whether this is a primitive plesiosauroid or a pliosauroid.
Features Thalassiodracon is a small primitive plesiosaur with a small head, about one tenth of the length of the whole animal, but this is large compared with later plesiosaurs. The snout is short and pointed and the skull lightly built. Unlike later plesiosaurs the hind limbs are bigger then those at the front. It has the long neck of the plesiosauroids, but the lower )aw, the hip bones and the larger hind limbs of the pliosauroids.