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The first reports on Deinonychus antirrhopus Ostrom tentatively identified a solitary, incomplete bone from the Yale Quarry near Bridger, Montana, as a right pubis. Subsequent examination and comparison with remains of other taxa have established that bone to be a right coracoid of surprisingly large size. The element is redescribed here with a corrected reconstruction of the pectoral girdle and a revised interpretation of the relevant pectoral musculature and functions. The unusually large size of the coracoid is believed to be related to enlarged pectoral muscles that were important in some predatory activities.