Platylithophycus

{{Short description|Extinct genus of elasmobranchs}}

{{Speciesbox

| fossil_range = {{fossil range|87|82|Coniacian-Campanian}}

| parent_authority = Johnson & Howell, 1948{{cite journal |last1=Johnson |first1=J.H. |last2=Howell |first2=B.F. |date=1948 |title=A new Cretaceous calcareous alga from Kansas |journal=Journal of Paleontology |volume=22 |issue=5 |pages=632–633 |jstor=1299601 |url=https://www.jstor.org/stable/1299601 |url-access=registration}}

| taxon = Platylithophycus cretaceus

| authority = Johnson & Howell, 1948

}}

Platylithophycus is an extinct genus of elasmobranchs that lived during the Late Cretaceous. It is known from a single specimen from the Niobrara Formation of Kansas, United States. It was originally identified as the fronds of a codiacean alga, then later as the cuttlebone of a cuttlefish.{{cite journal |last1=Miller |first1=H.W. |last2=Walker |first2=M.V. |date=1968 |title=Enchoteuthis melanae and Kansasteuthis lindneri, new genera and species of teuthids, and a sepiid from the Niobrara Formation of Kansas |journal=Transactions of the Kansas Academy of Science |volume=71 |issue=2 |pages=176–183 |doi=10.2307/3627369 |jstor=3627369 |url=https://www.jstor.org/stable/3627369 |url-access=registration}} It was most recently reidentified as the gill arches and rakers of an elasmobranch of uncertain affinities.{{cite journal |last1=Bronson |first1=A.W. |last2=Maisey |first2=J.G. |date=2018 |title=Resolving the identity of Platylithophycus, an enigmatic fossil from the Niobrara Chalk (Upper Cretaceous, Coniacian–Campanian) |journal=Journal of Paleontology |volume=92 |issue=4 |pages=743–750 |doi=10.1017/jpa.2018.14 |bibcode=2018JPal...92..743B |s2cid=135179588 }} It might have been a filter feeding mackerel shark related to Aquilolamna.{{cite journal |last1=Vullo |first1=R. |last2=Frey |first2=E. |last3=Ifrim |first3=C. |last4=González González |first4=M.A. |last5=Stinnesbeck |first5=E.S. |last6=Stinnesbeck |first6=W. |date=2021 |title=Manta-like planktivorous sharks in Late Cretaceous oceans |journal=Science |volume=371 |issue=6535 |pages=1253–1256 |doi=10.1126/science.abc1490 |pmid=33737486 |bibcode=2021Sci...371.1253V |s2cid=232271254 |url=https://hal-insu.archives-ouvertes.fr/insu-03174427/file/Vullo-etal-2021-HAL.pdf }}