Ornithodesmus cluniculus Seeley, 1887
Ornithodesmus cluniculus was first described by Harry Govier Seeley in 1887, based on a set of six fused vertebrae from the hip (sacrum), specimen number BMNH R187, found by William D. Fox in the Wessex Formation of Brook Bay. Seeley thought the bones came from a primitive bird, and gave it a name meaning "bird link", from Greek ὄρνις (ornis), "bird", en δεσμός (desmos), "link". The specific name cluniculus means "little buttock" in Latin, a reference to the small thighs indicated by the size of the specimen.
Illustration of Ornithodesmus sacrum in multiple views
Seeley, H. 1887. On a sacrum, apparently indicating a new type of Bird, Ornithodesmus cluniculus, Seeley, from the Wealden of Brook. Quarterly Journal of the Geological Society of London, 42: 206-211.