At least some external measurements are available for 29 specimens from Tierra del Fuego. Eleven females ranged from 124,6 (a calf) to 203,5 cm in length. Eleven animals of unknown sex were from 94 cm, the smallest animal found, to 201 cm. Seven males measured from 109 cm (a neonate) to 224 cm, the largest animal known. This probably does not represent the maximum size for the species.