Okay, imagine you're playing with a big basin of water. That's like what the Ouled Abdoun Basin is, but it's not actually water - it's a big hole in the ground that used to have a lot of really old rocks and fossils in it.
You know how you might find cool rocks or seashells at the beach? Well, scientists found lots of REALLY old rocks and fossils in the Ouled Abdoun Basin - they're over 60 million years old! These rocks and fossils can teach us a lot about what the world was like a long time ago, before people like you and me were even born.
Scientists think that the Ouled Abdoun Basin used to be a big lake or swamp a really long time ago, and that's why so many rocks and fossils ended up there. People have been studying the Ouled Abdoun Basin for a while now, and they keep finding new stuff there! It's like a treasure chest full of secrets from long ago.