 After determining the ranges of motion in the joints of the forelimb , the study went on to hypothesize about the predatory habits of Acrocanthosaurus . The forelimbs could not swing forward very far , unable even to scratch the animal 's own neck . Therefore , they were not likely to have been used in the initial capture of prey and Acrocanthosaurus probably led with its mouth when hunting . On the other hand , the forelimbs were able to retract towards the body very strongly . Once prey had been seized in the jaws , the heavily muscled forelimbs may have retracted , holding the prey tightly against the body and preventing escape . As the prey animal attempted to pull away , it would only have been further impaled on the permanently flexed claws of the first two digits . The extreme hyperextensibility of the digits may have been an adaptation allowing Acrocanthosaurus to hold struggling prey without fear of dislocation . Once the prey was trapped against the body , Acrocanthosaurus may have dispatched it with its jaws . Another possibility is that Acrocanthosaurus held its prey in its jaws , while repeatedly retracting its forelimbs , tearing large gashes with its claws . 
