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Western Interior Seaway

The Western interior seaway is a fascinating subject. In the late Cretaceous, (about 70 million years ago), an ocean split America in half. It was created when the Farallon and North American tectonic plates collided, causing the Rocky Mountains to rise. The Farallon plate went under the North American plate when that exact place was undergoing, um, undergoing. The North American plate was sinking at that time, and when the Farallon plate went under it, it made a shallow basin. Ocean water then flowed in, creating the Western interior seaway. The Arctic Ocean and the Gulf of Mexico were connected.

The Western interior seaway was a shallow sea with lots of life forms. What surprised most scientists was how many predators there were. One of the most common, (according to fossil records), was a type of shark that we call today Squalicorax. There were also many other predators, including (brace yourself) : Platecarpus, a bunch of crinoids, Cretoxyrhina, Xiphactinus, Mosasaurus, Styxosaurus, Plesiosaurs, and a whole load of other carnivores. Normally, there is a lot of stress put on an ecosystem with lots of predators, but there wasn’t very much stress on this one. This is because most of the animals ate different foods. For instance, Styxosaurus, with their long, slender necks and their tiny heads, they ate small fish even though they had large bodies. This probably helped with other creatures of its’ size. OK, well, I hope you had fun reading about the Western interior seaway, and please remember to recycle!

Here is a map of the Western interior seaway so you can get a better look at where it was.


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