Klasifikace a pojmenovávání taxonů je proces vázaný pravidly, která jasně určují jejich platnost. V některých ohledech ale může být jejich správná aplikace komplikovaná, hlavně v případě nedospělých jedinců, nebo exemplářů nerozpoznaného stupně individuálního vývoje. V průběhu života se totiž některé znaky mohou měnit a jejich korektní interpretace, zejména v případě fosilií, může být komplikovaná. Z oligocenních sedimentů Polska jsou uvedeny vybrané příklady fosilních ryb, u kterých byly identifikovány různé ontogenetické stupně.

Seznam použité a doporučené literatury:

BALON, E. 1975. Terminology of intervals in fish development. Journal of the Fisheries Research Board of Canada, 1975, 32.9: 1663-1670.
HIRASAWA, T.; OISI, Y.; KURATANI, S. Palaeospondylus as a primitive hagfish. Zoological Letters, 2016, 2: 1-9.
HUBBS, C.L. Dikellorhynchus and Kanazawaichthys: nominal fish genera interpreted as based on prejuveniles of Malacanthus and Antennarius, respectively. Copeia, 1958, 1958.4: 282-285.
HUBBS, C.L. Terminology of early stages of fishes. Copeia, 1943, 1943.4: 260.
JOHNSON, G.D.; PAXTON, J.R.; SUTTON, T.T.; SATOH, T.P.; SADO, T.; NISHIDA, M.; MIYA, M. Deep-sea mystery solved: astonishing larval transformations and extreme sexual dimorphism unite three fish families. Biology letters, 2009, 5: 235-239.
KENDALL A.W.; AHLSTROM, E.H.; MOSER, H.G. Early life history stages of fishes and their characters. In: MOSER, H.G.; RICHARDS, W.J.; COHEN, D.M.; FAHAY, M.P.; KENDALL, A.W. Jr.; RICHARDSON, S.L. (eds) Ontogeny and systematics of fishes : based on an international symposium dedicated to the memory of Elbert Halvor, 1984, 11-22. Lawrence. American society of ichthyologists and herpetologists.
PŘIKRYL, T. Notes on development of the Oligocene trachinid Trachinus minutus (Jonet, 1958). Palaeontographica Abteilung A, 2017, 308.1-3: 69-87.
PŘIKRYL, T. KANIA, I.; KRZEMINSKI, W. Synopsis of fossil fish fauna from the Hermanowa locality (Rupelian; Central Paratethys; Poland): current state of knowledge. Swiss Journal of Geosciences, 2016, 109.3: 429-443.
SETTE, O.E. Biology of the Atlantic mackerel (Scomber scombrus) of North America. Fishery bulletin, 1943, 38.50: 149-237.
SNYDER, D.E. Terminologies for intervals of larval fish development. In: BOREMAN, J. (Ed.) Great Lakes fish egg and larvae identification, 1976, 41-58. Michigan. Department of the Interior, Fish and Wildlife Service, Office of Biological Services, National Power Plant Team, Power, Power Plant Project.
SNYDER, D.E. Contributions to a guide to the cypriniform fish larvae of the upper Colorado River system in Colorado. Bureau of Land Management, Biological Sciences Series, 1981, 3: 1-81.

The classification and naming of taxa are processes bounded by rules that restrict their activity. The correct application of these rules may be complicated, especially in cases of non-mature specimens or in specimens with an undetermined level of ontogeny. Some features change during ontogeny and so their correct interpretation may be complicated, especially in fossil cases. Several examples of fossil fish determined to different ontogenetic stages are listed from the Oligocene sediments of Poland.