This is a groove that is sometimes converted into a foramen by ossification of the posterior atlantooccipital membrane to create a delicate bony spiculum which arches backward from the posterior end of the superior articular process.
22.
On the lateral aspect of the sacral groove is a linear series of tubercles produced by the fusion of the articular processes which together form the indistinct "'medial sacral crest " '.
23.
The superior articular processes are thin plates of bone projecting upward from the junctions of the pedicles and laminae; their articular facets are practically flat, and are directed backward and a little lateralward and upward.
24.
The posterior part of the arch presents above and behind a rounded edge for the attachment of the posterior atlantooccipital membrane, while immediately behind each superior articular process is the superior vertebral notch ( " sulcus arteriae vertebralis " ).
25.
The rear middle back vertebrae have a very high and deep depression between their rear articular processes and the base of the neural spine, 2.6 times higher than that base is long, measured from the front to the rear.
26.
The carpometacarpus was also peculiarly flattened on its top end; and the trochlea carpalis ( a bony articular process that drives wing extension and flexion ) is reduced and weak in shape, limiting wrist movement-both likely adaptations to a flightless lifestyle.
27.
It arises by tendons from the transverse processes of the upper four or five thoracic vertebrae, and the articular processes of the lower three or four cervical vertebrae, and is inserted into the posterior margin of the mastoid process, beneath the splenius capitis and sternocleidomastoid.
28.
The transverse processes arise from the arch behind the superior articular processes and pedicles; they are thick, strong, and of considerable length, directed obliquely backward and lateralward, and each ends in a clubbed extremity, on the front of which is a small, concave surface, for articulation with the tubercle of a rib.
29.
The article on transverse processes states : ( Hope its ok for me to copy and paste this )'The transverse or costal processes of a vertebra, two in number, project one at either side from the point where the lamina joins the pedicle, between the superior and inferior articular processes .'Take a look at Grays picture of a cervical vertebrae in the article.
30.
The flatness of the scute is another unusual characteristic, giving it the species name " flatum " . " Jiyuanitectum " shares several features in common with the chroniosuchians " Synesuchus " and " Bystrowiella ", including the upper surface of the scute being covered in ridges that are mostly oriented perpendicular to the midline, and the absence of a bony projection on the front of the scute called the anteromedial articular processes, which is seen in other chroniosuchians.
