It's commonly used in scientific names for dinosaurs and other extinct reptiles, as well as some modern reptiles.
Here are some examples:
* Sauropoda (meaning "lizard foot") is a group of long-necked, herbivorous dinosaurs.
* Saurischia (meaning "lizard hip") is a group of dinosaurs that includes theropods (like T. rex) and sauropods.
* Iguana (meaning "iguana lizard") is a genus of large, herbivorous lizards native to the Caribbean, Central America, and South America.
So, whenever you see "sauros" in a scientific name, you know it's referring to a lizard or reptile of some sort.