The 13-metre-long marine reptile fossil of "Bruce" has been at the centre since 2003, and on the weekend the centre unveiled a nine-metre-long mosasaur fossil named "Suzy."
Suzy was found in 1977, not far from the area northwest of Morden where Bruce was discovered in 1974.
The executive director of the centre, Peter Cantelon, says it's awesome to bring the skeletons together after they were apart for anywhere between 40 and 80 million years.
Bruce is officially recognized by Guinness World Records as the largest mosasaur on public display.
The centre says mosasaurs were fierce predators, and were once the top of the food chain in the Western Interior Seaway that split North America in two.
It says palaeontologists think the mosasaurs' lineage was branched off from a lizard group known today as the monitor lizards.