Other members of the family Testudinidae are generally small (7–35 cm (2.8–13.8 in) long). C. atlas is the largest known member of the family, with a shell length of about 2.1 m (6.9 ft), an estimated total length of 2.5 to 2.7 m (8.2 to 8.9 ft), and an approximate total height of 1.8 m (5.9 ft). Weight estimates vary greatly: some go as high as 3 to 4 metric tonnes (3000 to 4000 kg), but a weight of around 1 mt (1000 kg) is probably more realistic.[4] The only larger turtles were the oceanic Archelon and Protostega from the Cretaceous period, and the aquatic Stupendemys of the South American late Miocene. In life, C. atlas would have resembled a giant Galápagos tortoise.