Traskasaura sandrae: Canada’s “Sea Monster” Elasmosaur Revealed as a 12-Meter Predator from 85 Million Years Ago

A bizarre new elasmosaurid plesiosaur, Traskasaura sandrae, has been formally named from Late Cretaceous fossils on Vancouver Island, British Columbia. Measuring up to 12 meters (39 feet) long, this “very odd” marine reptile combined primitive and derived traits unlike any other known elasmosaur, offering fresh insight into the diversity of apex predators that once ruled the northern Pacific.

The story began in November 1988 when Michael Trask and his daughter Heather discovered the first specimen along the banks of the Puntledge River in the Haslam Formation of the Nanaimo Group. Dated to the Santonian stage (~86–84 million years ago), the fossils include neck vertebrae, an isolated humerus, and an exceptionally preserved juvenile skeleton preserving the thorax, girdles, and limbs. Initially described in 2002 and later declared British Columbia’s official provincial fossil emblem, the material defied easy classification until a new international analysis unlocked its secrets.

Published on May 23, 2025, in the Journal of Systematic Palaeontology, the study by lead author F. Robin O’Keefe and colleagues from Canada, Chile, and the United States highlights Traskasaura’s unique anatomy: a striking mosaic of basal and advanced features in its vertebrae and limb bones. These traits suggest a powerful swimmer capable of ambush predation. Its robust teeth were suited for crushing shelled prey such as ammonites (Pachydiscus), positioning it as a formidable hunter in the shallow seaways that covered much of western Canada during the Cretaceous.

Named in honor of the Trask family and Sandra Lee O’Keefe, the late wife of the lead author and a breast-cancer warrior, the genus combines “Trask” with the Greek saura (lizard). The species name sandrae commemorates her. The holotype and additional material are housed at the Courtenay and District Museum, where they continue to inspire public fascination.

This discovery underscores how even well-known fossils can yield surprises with modern techniques and fresh comparative data. As the first elasmosaurid formally named from British Columbia, Traskasaura sandrae enriches our picture of Santonian marine ecosystems and reminds us that the “sea monsters” of the dinosaur age were far stranger—and more regionally diverse—than previously imagined.