 A holotype, the holotype is a single physical example or illustration of an organism, known to have been used when the species or lower-ranked accent was formally described. It is either the single such physical example or illustration or one of several such, but explicitly designated as the holotype. Under the international code of zoological nomenclature ICZN the holotype is one of several kinds of name-bearing types. In the international code of nomenclature for algae, fungi, and plants ICN and ICZN the definitions of types are similar in intent but not identical in terminology or underlying concept. For example, the holotype for the butterfly lysidzitis launchinus is a preserved specimen of that species, held by the Museum of Comparative Zoology at Harvard University. An isotope is a duplicate of the holotype and is often made for plants, where holotype and isotopes are often pieces from the same individual plant or samples from the same gathering. The holotype is not necessarily typical of that taxon, although ideally it should be. Sometimes just a fragment of an organism is the holotype, particularly in the case of a fossil. For example, the holotype of Pilarosaurus humrocrystatus deriated in a large herbivorous dinosaur from the early Jurassic period, is a fossil leg bone stored at the natural history museum in London. Even if a better specimen is subsequently found, the holotype is not superseded.