The vertebrae near the base of the tail are extremely useful for classifying sauropods. Derived titanosaurs had vertebrae that were convex on the front and back. Primitive sauropods had vertebrae that were either flat on both ends (amphiplaty) or concave on both (amphicoely). "Venenosaurus" may have had a condition intermediate between the two. The possession of amphiplatyan caudal centra with anteriorly facing neural spines is a unique identifier of this species. Sometimes the form of central articulations change within a single individual's vertebral column.