Cretaceous Seas Exhibit
Cretaceous Seas is the largest marine vertebrate exhibit in Calgary. Installed from the atrium ceilings in Mount Royal’s East Gate and B-Wing, Cretaceous Seas provides students and the public the opportunity to view life-sized specimens of extinct marine reptiles and fishes that swam or flew the seas of western North America during the Cretaceous Period, more than 65 million years ago. The casts on display were constructed from molds produced from bones of marine reptiles, pterosaurs and fishes unearthed from sea bottom muds deposited in the Western Interior Seaway.
What is the Cretaceous Period?
The Cretaceous Period (144-65 million years ago), the final interval of the Mesozoic Era, ended about 64 million years before the first humans evolved. Several times during the Late Cretaceous, sea level rose, flooding extensive areas of continents including the interior of North America. During the Cretaceous Period, pressures from oceanic plates plunging below North America crumpled the western margin to produce the Cordilleran Mountains. But, further eastward, the continent warped downward. The result was the incursion of marine waters into the continent’s interior to produce the Western Interior Seaway, a shallow watermass (< 200 m deep) that for much of its history extended from the Gulf of Mexico to the Arctic Ocean.
Much of Alberta was covered by marine waters during mid to Late Cretaceous time. In these mild to cool temperate waters, predatory marine reptiles including mosasaurs, plesiosaurs and ichthyosaurs flourished. Nearly complete skeletons of marine reptiles are known from southern Alberta and near Fort McMurray where Cretaceous marine strata are exposed.
The flying reptile Pteranodon (twice the size of the largest living flying birds) is the most common pterosaur in Upper Cretaceous sediments of the Western Interior Seaway of North America, with about 1,200 specimens recovered to date. So far though, none is known from Canada, the most northerly records coming from North Dakota.
With more vertebrae than any other known animal, the plesiosaur Elasmosaurus developed a remarkably long neck that supported a small snake-like head. The short tail suggests Elasmosaurus was a slow swimmer that relied on large flippers powered by massive swimming muscles inserting on heavy ventral bones. The neck could be retracted into a shallow, lateral, sigmoidal curve enabling a snake-like retraction and strike to capture fishes and cephalopods.
Enchodus is an extinct genus of bony fish that flourished during the Late Cretaceous with a near global distribution. An important member of Cretaceous marine food webs, Enchodus avoided the mass extinction at the end of the Mesozoic Era and survived another 20 million years, well into the Cenozoic Era.
While more closely related to salmon and trout than herring, Enchodus earns its nickname, the “sabre-toothed herring,” from the prominent fangs at the front of its jaws. Formidable teeth, together with a sleek body and large eyes, indicate Enchodus was an active predator. But, Enchodus too was sometimes prey. Its remains have been recovered from stomach contents of other Cretaceous predators including mosasaurs, sharks, plesiosaurs and seabirds.
Platecarpus, like other mosasaurs, was an aquatic lizard-like reptile that shows remarkable adaptations for a seafaring life. The downturned tail supported a crescent-shaped tail fluke. With flipper-like limbs for steering, the tail likely propelled the animal with a shark-like motion rather than the snake-like undulations proposed by earlier researchers. Preserved gut-contents show mosasaurs feasted mostly on fishes, flightless aquatic birds, and other marine reptiles.
An extinct genus of marine turtle, Protostega is known from Upper Cretaceous deposits in both Canada and the United States. The cast specimen on display at Mount Royal University is a juvenile. Adults grew to more than three metres in length, with a weight of about two tons, making Protostega one of the largest turtles in Earth history.
Unlike most turtles, the carapace of Protostega is lightly constructed and probably supported a soft shell similar to that of modern leatherback turtles. This lightweight construction, together with powerful front flippers, suggests Protostega was a tireless swimmer. Just as marine turtles do today, females in the Western Interior Seaway likely migrated hundreds of kilometres to lay eggs on sandy beaches.
For more information or to book a tour, please contact Cindy Greschner, Administrative Assistant for the Department of Earth and Environmental Sciences at email@example.com or call 403-440-6615.