[1] TMP 2007.011.0001 was discovered during mining for gem-quality ammonite shell called Ammolite by Korite International Ltd. about 150 meters south of the St. Mary River near Lethbridge in southern Alberta, when an excavator bucket accidentally struck and smashed through the fossil, destroying parts of the mid-trunk dorsal and ventral ribs, as well as an unknown number of gastroliths.

[1][2] The specimen was excavated in a nearly completely articulated state from dark gray claystone in a concretionary horizon about 15 m above the base of the Bearpaw Formation and about 2 m below an ash bed known by mine workers as the "10 inch bentonite".

Collected from the lower part of Muddy Unit 1 of the St. Mary River Section, just below the lowest known local occurrence of Baculites compressus in the formation, the specimen is not younger than about 73.5 million years old and approximately of that age, thus dating to the middle of the upper Campanian stage of the Late Cretaceous.

Additional traits rarely seen in other elasmosaurids include: a tapered front-side projection on the pubis that extends to the side beyond the acetabulum, a longitudinal ridge on the side of most neck vertebrae up to cervical 69, a clavicular arch that is wider than the adjacent front edge of the scapula, the lack of pectoral and pelvic bar, a tip of the tail that is made of seven fused tail vertebrae, and a slender humerus with a width-to-length ratio of 0.56, among other traits.

Albertonectes is known from a mature individual, as suggested by the fused neural spines and most cervical ribs to their centra, and by the only partial connection between the trochanter and the capitulum (head) of the femur, seen in TMP 2007.011.0001.