 This grouping is based on a variety of shared characters, including the possession of an otic trough, having similar atlas-axis complexes, the possession of small posttemporal fenestrae, the possession of a small parietal foramen, the structure and position of the septomaxillae, and the possession of a tall, broad, and flat illium.Most recently, a study of the inner ear morphology of diadectomorphs using X-ray microcomputed tomography by Klembara et al.also supported the close relationship between diadectomorphs and synapsids.