Females have large, highly distensible stomachs which give the ventral region a flabby appearance. The gas bladder is absent and the stomach is highly distensible. The aorta is an elastic artery, and as such is quite distensible. Mouths are large, with distensible jaws, and there is no orbitosphenoid. Sabertooths do not have swim bladders, and the stomach is highly distensible.