Simplify the following text for a Grade 10 native English-speaking person.
Original: The Deinonychosauria ( `` fearsome claw lizards '' ) were a successful clade of theropods in the Late Jurassic and Cretaceous Periods .
Simplified: The Deinonychosauria ( `` fearsome claw lizards '' ) is a clade of theropods in the Late Jurassic and Cretaceous periods .