It was collected in the 1980s from the Calcaire à Bélemnites Formation of Normandy, dating to the latest Pliensbachian stage of the late Early Jurassic, about 185-183 million years ago.

[1] Cryonectes is characterized by a unique combination of characters including a very slight constriction between premaxillae and maxillae, its snout is greatly elongated and the mandible has a long symphysis bearing seven tooth position and retaining a ventral mandibular ridge.

[1] A cladistic analysis performed by Peggy Vincent, Nathalie Bardet and Emanuela Mattioli found it to be basal to Pliosaurus, Peloneustes and other pliosaurids.

The generic name is derived from kryos, Greek for "cold", and nektris (nektes), for "swimmer", and refers to the cool climatic conditions that prevailed during the uppermost Pliensbachian.

The specific name is derived from the Frank kingdom of Neustrie which covered northwest France, created after the death of Clovis I.