Eastern Diamondback Rattlesnake (Crotalus adamanteus) is a venomous pit viper species native to the southeastern United States. It is the largest rattlesnake species and is known for the distinctive diamond pattern on its back. The other options are incorrect: ants are insects, chameleons are lizards primarily found in Africa (not specifically associated with 'Eastern' in the name), and turtles are reptiles with shells.