When Phobos describes the first male Earthling he saw in the pawn shop to Martian Central Control, he says that the subject's head was of medium size, with a cranial volume of about 3,000 cc. Living humans have a cranial capacity ranging from about 950 cc to 1800 cc, with the average about 1400 cc.
The identification cards displayed by the two Martians at the pawn shop are identical, although they supposedly describe the individuals differently.
Though Carla is frozen in time, she can be seen swaying slightly.