Kenneth Lacovara, PhD, with the 30-foot tail of Dreadnoughtus schrani, stretching along the length of the wall and around the corner in his lab. Beside Lacovara's hand is a set of chevron bones. Pairs of these chevrons run beneath each of the tail vertebrae and were found for each vertebra in the tail of Dreadnoughtus. In this animal the chevrons are noteworthy for the wide area for muscle attachment on the lower portion of the Y-shaped chevron. In Dreadnoughtus this attachment area is broad and spatula-shaped, allowing for extremely large tail muscles -- giving this animal an extraordinarily powerful, 'weaponized' tail in Lacovara's description.