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".
Seeley assumed the bones belonged to a primitive bird-like creature, and created a name that reflected this relationship, combining elements of Greek words for "bird" (ὄρνις) and "link" (δεσμός).