Currently on display at Chicago's Field Museum, "Sue" is the most complete Tyrannosaurus rex skeleton ever found. Although the fossilized bones were unearthed 20 years ago, scientists recently discovered the remains of a previously-unknown shark that co-existed along with the dinosaur – and the fish has been named after a classic video game.

Due to the fact that sharks have cartilaginous skeletons which don't fossilize, all that were found were approximately two dozen of the creature's tiny teeth.

Shaped like the alien spaceships from the 80s video game Galaga, these teeth were each less than one millimeter across – they were discovered by Field Museum volunteer Karen Nordquist, as she was sifting through some of the leftover sediment in which Sue's bones were found. As a result, the "new" shark has been named Galagadon nordquistae.

The freshwater fish is thought to have been only 12 to 18 inches long (305 to 457 mm), and was likely related to modern-day "carpet sharks" such as the wobbegong. It would have swum up from the sea into rivers in what is now South Dakota, during the Cretaceous period – about 67 million years ago. Its teeth (pictured above) were probably designed for crushing the shells of invertebrate prey such as snails and crayfish.

"Every species in an ecosystem plays a supporting role, keeping the whole network together," says North Carolina State University lecturer Terry Gates, lead author of a paper on the discovery. "There is no way for us to understand what changed in the ecosystem during the mass extinction at the end of the Cretaceous without knowing all the wonderful species that existed before."

The paper was recently published in the Journal of Paleontology.

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