In Kentrosaurus (MB R.3613; MB R.3618; MB R.3615.1–8; MB R.3617; MB R.4572; MB R.3619; [36 ]: pl. 2), the number of fused vertebrae forming the sacrum varies from four to seven, and there appear to be both dorsosacrals and caudosacrals added to the sacral rod.
Source: wiktionary