Elasmosaurs

Elasmosaurs generally have the look of oversized, shellless turtles with long necks.

Source: tatoeba (5479534)

Elasmosaurs are a genus of plesiosaur that lived in North America during the Late Cretaceous.

Source: tatoeba (9171123)

And when we consider the fact that some species of the elasmosaurs had a neck not less than twenty feet in length, such a flexible use of it would not seem improbable.

Source: tatoeba (11589828)