This obliterated the sutures between skull elements, which is common for adult ankylosaurs. It possessed features of both stegosaurs and ankylosaurs. Polacanthinae is a grouping of ankylosaurs, possibly primitive nodosaurids. They preyed upon herbivorous dinosaurs such as hadrosaurs, ceratopsians and ankylosaurs. This morphotype has been compared to the armor of ankylosaurs. A few other ankylosaurs reached about in length. The latter is believed to have been the ancestor of all stegosaurs and ankylosaurs. While this body form is similar to that of ankylosaurs, it resulted from convergent evolution. The heavy-built ankylosaurs "Talarurus" and "Tsagantegia". The quadratojugal, squamosal and orbital horns are poorly preserved, in contrast with other ankylosaurs. Undescribed ankylosaurs present in both upper Shishugou and Wucaiwan members. Thyreophora is characterized by body armor and includes stegosaurs, ankylosaurs, "Scelidosaurus", and "Scutellosaurus". Unlike other ankylosaurs, its nostrils faced sideways rather than towards the front. By this time, the dome-headed dinosaurs were either considered relatives of ornithopods or of ankylosaurs. This shield is also found in ankylosaurs like "Polacanthus" and "Antarctopelta".