Editing Pterodactylus (section)

===Controversial species===
[[File:Bsp as xix.png|thumb|Juvenile type specimen of ''Pterodactylus kochi'', now reassigned as ''[[Diopecephalus kochi]]'']]
The only well-known and well-supported species left by the first decades of the 21st century were ''P. antiquus'' and ''P. kochi''. However, most studies between 1995 and 2010 found little reason to separate even these two species, and treated them as synonymous.<ref name="unwin2003">{{cite journal |last1=Unwin |first1=D. M. |year=2003 |title=On the phylogeny and evolutionary history of pterosaurs |journal=Geological Society, London, Special Publications |volume=217 |issue=1 |pages=139–190 |doi=10.1144/GSL.SP.2003.217.01.11 |bibcode=2003GSLSP.217..139U |s2cid=86710955}}</ref> More recent studies of pterosaur relationships have found anurognathids and pterodactyloids to be sister groups, which would limit the more inclusive group [[Caelidracones]] to just two clades.<ref name=LoneStarPterosaurs>{{Cite journal |last1=Andres |first1=B. |last2=Myers |first2=T. S. |doi=10.1017/S1755691013000303 |title=Lone Star Pterosaurs |journal=Earth and Environmental Science Transactions of the Royal Society of Edinburgh |pages=383–398 |year=2013 |volume=103 |issue=3–4 |s2cid=84617119}}</ref><ref name=SCB06 /> In 1996, Bennett suggested that the differences between specimens of ''P. kochi'' and ''P. antiquus'' could be explained by differences in age, with ''P. kochi'' (including specimens alternately classified in the species ''P. scolopaciceps'') representing an immature growth stage of ''P. antiquus''. In a 2004 paper, Jouve used a different method of analysis and recovered the same result, showing that the "distinctive" features of ''P. kochi'' were age-related, and using mathematical comparison to show that the two forms are different growth stages of the same species.<ref name="jouve2004" /> An additional review of the specimens published in 2013 demonstrated that some of the supposed differences between ''P. kochi'' and ''P. antiquus'' were due to measurement errors, further supporting their synonymy.<ref name=BennettPZ />

By the 2010s, a large body of research had been developed based on the idea that ''P. kochi'' and ''P. scolopaciceps'' were early growth stages of ''P. antiquus''. However, in 2014, two scientists began publishing research that challenged this paradigm. Steven Vidovic and David Martill concluded that differences between specimens of ''P. kochi'', ''P. scolopaciceps'', and ''P. antiquus'', such as different lengths of neck vertebrae, thinner or thicker teeth, more rounded skulls, and how far the teeth extended back in the jaws, were significant enough to separate them into three distinct species. Vidovic and Martill also performed a phylogenetic analysis which treated all relevant specimens as distinct units, and found that the ''P. kochi'' type specimen did not form a natural group with that of ''P. antiquus''. They concluded that the genus ''Diopecephalus'' could be returned to use to distinguish ''"P". kochi'' from ''P. antiquus''. They named the new genus ''[[Aerodactylus]]'' for ''P. scolopaciceps'' as well. So, what Bennett considered early growth stages of one species, Vidovic and Martill considered representatives of new species.<ref name=Aerodactylus>{{Cite journal |doi=10.1371/journal.pone.0110646 |title=''Pterodactylus scolopaciceps'' Meyer, 1860 (Pterosauria, Pterodactyloidea) from the Upper Jurassic of Bavaria, Germany: The Problem of Cryptic Pterosaur Taxa in Early Ontogeny |journal=PLOS ONE |volume=9 |issue=10 |pages=e110646 |year=2014 |last1=Vidovic |first1=S. U. |last2=Martill |first2=D. M. |pmid=25337830 |pmc=4206445 |bibcode=2014PLoSO...9k0646V |doi-access=free}}</ref><ref name=W1837>{{cite journal |last1=Vidovic |first1=Steven U. |last2=Martill |first2=David M. |title=The taxonomy and phylogeny of ''Diopecephalus kochi'' (Wagner, 1837) and ''"Germanodactylus rhamphastinus"'' (Wagner, 1851) |journal=Geological Society, London, Special Publications |volume=455 |date=2017 |issue=1 |pages=125–147 |url=https://eprints.soton.ac.uk/423063/1/Vidovic_Martill_2017_Taxonomy_of_Diopecephalus_and_Germanodactylus_AM_with_Figures.pdf |doi=10.1144/SP455.12 |bibcode=2018GSLSP.455..125V |s2cid=219204038}}</ref>

In 2017, Bennett challenged this hypothesis, he claimed that while Vidovic and Martill had identified real differences between these three groups of specimens, they had not provided any rationale that the differences were enough to distinguish them as species, rather than just individual variation, growth changes, or simply due to crushing and distortion during the fossilization process. Bennett pointed in particular to the data used to distinguish ''Aerodactylus'', which was so different from the data for related species, it might be due to an unnatural assemblage of specimens. As a result, Bennett continued to consider ''Diopecephalus'' and ''Aerodactylus'' simply as year-classes of immature ''Pterodactylus antiquus''.<ref name=bennett_2017_pteranodon_juv>{{cite journal |last1=Bennett |first1=S.C. |year=2017 |title=New smallest specimen of the pterosaur ''Pteranodon'' and ontogenetic niches in pterosaurs |journal=Journal of Paleontology |volume=92 |issue=2 |pages=1–18 |doi=10.1017/jpa.2017.84 |s2cid=90893067}}</ref>