Kentrosaurus: Difference between revisions

The neck was composed of 13 [[Cervical vertebrae|cervical]] (neck) vertebrae, the first being the [[Atlas (anatomy)|atlas]] which was strongly fused to the occipital region of the skull and followed by the [[Axis (anatomy)|axis]]. The other 11 cervicals had hourglass-shaped [[Vertebra|centra]] (the base of a vertebra) and rounded ventral [[Keel (anatomy)|keels]]. The [[diapophyses]] are large and strongly angled posteriorily and parallel to each other. The spinous processes got larger towards the posterior end, while the [[Articular processes|postzygapophyses]] became smaller and less horizontal, giving the anterior part of the neck lots of mobility laterally. The dorsal column consists of 13 [[Thoracic vertebrae|dorsal]] (back) vertebrae which are tall and have short centra. TheThey have a [[neural arch]] more than twice as high as the centrum, the vertebral body, and almost completely occupied by the extremely spacious [[neural canal]], a trait unique to ''Kentrosaurus.'' The diapophyses too were laterally elongated, creating a Y-shape in anterior view. The [[sacrum]] (part of pelvis with vertebrae) consists of 6 fused centra, the first being a loose sacrodorsal, while the rest of the centra's [[transverse processes]] (extensions of bone) are fused to the dorsal parts of the [[Rib cage|sacral ribs]] into a solid sacral plate. The ribs also fuse to the [[Ilium (bone)|ilium]] (the upper part of the pelvis) creating a fully ankylosed and solid sacrum. The ilium is notable in that the preacetabular process, front blade, of the [[Ilium (bone)|ilium]] widens laterally, to the front outer side, and does not taper unlike in all other stegosaurs. Another characteristic is that the length of the ilium equals, or is greater than, that of the thigh bone.<ref name="MallisonRealLecto" /> The [[Vertebra|caudal]] (tail) vertebrae are 29 in number, though 27-29 are coossified for attachment to the thagomizers (tail spikes). The caudal vertebrae are very unique, as they have a combination of transverse processes up to the 28th vertebra and rod-shaped processes on the posterior caudals. These posterior caudal processes have narrow bases that do not tough the plate formed by the fusion of the processes of the sacral vertebrae. ''Kentrosaurus'' can be distinguished from other members of the [[Stegosauria]] by a number of processes of the vertebrae, which in the tail do not run sub-parallel, as in most dinosaurs. In the front third of the tail, they point backwards, the usual direction. In the middle tail, however, they are almost vertical, and further back they are hook-shaped and point obliquely forward. The [[Chevron (anatomy)|chevrons]], bones pointing to below from the bottom side of the tail vertebrae, have the shape of an inverted T.<ref name="MallisonRealLecto" />