Axial segmentation is key to the body plan organization of many metazoan groups and has arisen repeatedly throughout animal evolution (Davis and Patel, 1999). Within vertebrates, the axial skeleton is ...

The axial skeleton comprises of the skull, hyoid, auditory vesicles, ribs, sternum and the vertebral column. The appendicular skeleton comprises the upper and lower limbs, pelvic and the pectoral ...

The vertebrae of Elpistostege are known from a series of approximately 16 that show no heterogeneity in their length or shape; ribs were not found in association with these vertebrae, and their ...

Changes in the axial skeleton drive that process in most cases, either through elongation or addition of vertebrae 1, 2, 3, 4, 5 (Fig. 1).