 In Stegosaurus stenops there are 27 bones in the vertebral column anterior to the sacrum , a varying number of vertebrae in the sacrum , with four in most subadults , and around 46 caudal ( tail ) vertebrae . The <unk> are divided into cervical ( neck ) and dorsal ( back ) vertebrae , with around 10 cervicals and 17 dorsals , the total number being one greater than in Hesperosaurus , two greater than Huayangosaurus , although <unk> preserves 17 cervicals and an unknown number of dorsals . The first cervical vertebra is the axis bone , which is connected and often fused to the atlas bone . Farther posteriorly , the proportionately larger the cervicals become , although they do not change greatly in anything other than size . Past the first few dorsals , the centrum of the bones become more elongate front @-@ to @-@ back , and the transverse processes become more elevated dorsal . The sacrum of S. stenops includes four sacral vertebrae , but one of the dorsals is also incorporated into the structure . In some specimens of S. stenops , a caudal is also incorporated , as a <unk> . In Hesperosaurus there are two <unk> , and only four fused sacrals , but in Kentrosaurus there may be as many as seven vertebrae in the sacrum , with both <unk> and <unk> . S. stenops preserves 46 caudal vertebrae , and up to 49 , and along the series both the <unk> and the neural spines become smaller , until the neural spines disappear at caudal 35 . Around the middle of the tail , the neural spines become bifurcated , meaning they are divided near the top . 
