The holotype (which is currently the only known specimen) consists of the skull, neck, parts of the spine and the left front flipper.

The specimen's skull is complete and was preserved in articulation with a series 25 cervical (neck) vertebrae.

[1] Druckenmiller estimated the total length of Edgarosaurus to be roughly 3.2–3.7 meters (10–12 ft), a figure derived from the proportions of Dolichorhynchops and Peloneustes.

The top of skull of Edgarosaurus possesses a small opening towards its back known as a pineal foramen.

The first digit of its forelimb consists of seven bones, the second eleven, and the third ten, while the fourth and fifth bear nine.