Original: Apatosaurus ( ) , also known by the popular but obsolete synonym Brontosaurus , is a genus of sauropod dinosaur that lived about , during the Jurassic Period ( Kimmeridgian and Tithonian ages ) .
Simplified: Another dinosaur species discovered in 1994 was at first named A. yahnahpin , but in 1998 , it was renamed Eobrontosaurus yahnahpin .