 In 1889, the original type specimen of "I. trigonus" used by richard Owen was thought to be lost, and so Lydekker named several isolated vertebrae as the "type" of this species, though during this time there was no formal concept of a neotype.This created a problem, because the vertebrae selected by Lydekker came from unknown sediments and were not definitely associated with the original specimens named and described by Owen.Matters were complicated when the original holotype used by Owen was re-discovered, making the designation of a neotype unnecessary.