Sundance Sea facts for kids
The Sundance Sea was a large, shallow sea that covered much of western North America a long, long time ago, during the Jurassic period. Imagine a huge part of what is now Canada and the western United States being underwater! This ancient sea was actually connected to what we now call the Arctic Ocean. Over millions of years, the land to the west started to rise, causing the Sundance Sea to slowly shrink and move back.
How the Sundance Sea Changed
The Sundance Sea didn't just appear and disappear once. Scientists believe it was actually a series of five times the sea moved in and out. Each time the sea came in, it was called a "marine transgression." Between these times, the land would dry out, and rocks and soil would get worn away by erosion.
The sea kept moving in and out from the middle of the Jurassic period onwards. When the sea finally moved back for the last time, late in the Jurassic, it left behind layers of rock. On top of these sea rocks, new layers of dirt and rocks from the rising land to the west were laid down. These land-based rocks are now known as the Morrison Formation.
The rocks that formed in and around the Sundance Sea are often full of amazing fossils. These fossils tell us a lot about the animals that lived there!
Animals of the Sundance Sea
The Sundance Sea was home to many different kinds of animals. It was like a busy underwater city!
- Shellfish: The oyster called Gryphaea was super common, and you could find many clams and sea lilies on the seafloor.
- Fish and Squid-like Creatures: Fish, belemnites (which looked like squid with internal shells), and ammonites (shelled creatures like snails) swam together in big groups.
- Sharks: Even shark teeth have been found, showing that these ancient predators were around.
- Giant Marine Reptiles:
* Ophthalmosaurus was a large ichthyosaur, a type of "fish-lizard." It used its long jaws to catch belemnite "squid." * Pantosaurus was a plesiosaur, a long-necked marine reptile about the size of a seal. It hunted for fish. * The biggest marine reptile in the Sundance Sea was Megalneusaurus. This was a huge pliosaur, similar to the famous Liopleurodon. Fossils of Megalneusaurus have been found in places like Alaska and Wyoming, which were both covered by the Sundance Sea when this giant creature was alive.
When the sea moved back and the land was dry, dinosaurs and other Jurassic animals walked along the shores. They left behind their fossil footprints, which we can still find today!
Related pages
- Western Interior Seaway (This was another large inland sea, but it existed later, during the Cretaceous period.)
