Toxochelys was a prehistoric sea turtle that lived during the Late Cretaceous. It was closer to some kind of a transitional species between land-dwelling and sea turtles. It is possible that it swam in the Western Interior Seaway's coasts that meet Hell Creek, even though no fossils are known from this formation. Toxochelys is known, however, from the nearby Fox Hills formation.
An illustration featuring Brodavis hunting baby Toxochelys in Saurian: A Field Guide to Hell Creek, by J.W. Kirby.
In Saurian[]
It is slated for appearance in Saurian, as an AI, but currently only concept art is known. The animal was only lightly featured in the artbook, so its appearance in Saurian is dubious.