Plesiosauroids in which tooth oranment is absent: the teeth are greatly recurved, sharply pointed and buccolingually compressed; the premaxilla bears at least 8 teeth; the dentary bears 36 teeth on each ramus; the parietals do not form a sagital crest; the quadrate overlaps the quadrate ramus of the pteryogoid anterolaterally; the paraoccipital process of the exoccipital-opisthotic is realtively short and massive; the occiptal condyle is not ringed by a groove, and extends onto the pedicles of the exocciptal. The postcranial skeleton is not known

In reference to the stratigraphical horizon of the type specimen in the Kimmeridgian stage, Kimmeridge Clay, Greek, sauros, 'lizard': Kimmeridge lizard.