Absent or minimally ossified vertebrae

Lisowicia is an extinct genus of giant dicynodont synapsid that lived in what is now Poland during the late Norian or earliest Rhaetian age of the Late Triassic Period. Lisowicia is the largest known dicynodont, as well as the largest non-mammalian synapsid, and is estimated to have weighed between 5–6 tons, comparable in size to modern elephants. [Source: Wikipedia ]