Yaverlandia

Yaverlandia (meaning "of Yaverland Point/Yaverland Battery") is an extinct genus of possible dinosaur known from two partial fossil skulls found in Lower Cretaceous strata of the Wessex Formation (Upper Silty Bed) in the Isle of Wight, England. When the first known specimen, MIWG 1530, was first described in 1930 by D. M. S. Watson, similarities were noted with the ornithopod genus Vectisaurus (now Mantellisaurus) and the theropod genus Troodon. In 1936, it was ultimately assigned to the former. It was recognised as a distinct genus in 1971 by Peter Galton, who re-examined the remains. Galton described a single species, Yaverlandia bitholus, in the genus. He believed that it was the oldest member of the family Pachycephalosauridae. Subsequent research by Darren Naish in 2008 instead suggested affinities with maniraptoran theropods. IWCMS. 2012.585, a second specimen described in 2026 by Naish and Steven C. Sweetman, is very similar to the first specimen. These researchers determined that the identity of Yavelandia remains enigmatic; while dinosaur affinities remain possible, some anatomical features are comparable to non-dinosaurian reptiles such as crocodyliforms.

==Discovery and naming== The holotype (MIWG 1530) of Yaverlandia, consisting of two frontal bones, part of the right postorbital, and part of the left orbitosphenoid was discovered in 1930, in the Wealden Marls north of the seawall below Yaverland Battery of Sandown, on the Isle of Wight. It originated from strata belonging to the Wealden Group, presumably the Wessex Formation, which on the Isle of Wight dates to the Hauterivian and Barremian ages. The specimen was first mentioned in the literature by D. M. S. Watson in an untitled article in the Proceedings of the Isle of Wight Natural History Society. Watson noted that it bore similarities to Vectisaurus, then very poorly understood, though also noted similarities with the North American genus Troodon. Six years later, W. E. Swinton assigned MIWG 1530 to Vectisaurus.