palaeophiid

Palaeophiids were a group of extinct marine reptiles that belonged to the order Plesiosauria, within the broader clade of Sauropterygia. The family Palaeophiidae is best known for its distinctive long, eel‑shaped bodies and reduced necks, a morphology that set it apart from the typical long‑necked plesiosaurs. The type genus, Palaeophis, was first described in the early 20th century from remains found in the Hettangian stage of the Early Jurassic period in Europe.

These reptiles were adapted to an aquatic lifestyle, as evidenced by their streamlined bodies and elongated neural spines. Fossil evidence indicates that palaeophiids inhabited shallow marine environments, although some species may have exploited coastal and lagoonal habitats. Their vertebral column shows a high degree of flexibility, allowing efficient undulatory locomotion. Palaeophiid skulls are small relative to body size, with a simplified jaw structure and reduced dentition, suggesting a diet of small fish and invertebrates.

Palaeophiids are noted for their evolutionary significance within the plesiosaur lineage. Their morphological changes, including the reduction of the neck and increase in body length, represent a convergent adaptation toward specialized marine predation. The scarcity of well-preserved specimens, however, limits detailed understanding of their internal anatomy and phylogenetic relationships with other marine reptiles of the time.

Overall, palaeophiids occupy an important niche in the study of marine reptile evolution, illustrating how early marine reptiles experimented with diverse body plans to exploit the shallow seas of the Early Jurassic.