{{Short description|Extinct genus of mackerel shark}} {{Automatic taxobox | image = | image_caption = | taxon = Protolamna | authority = Cappetta, 1985 | fossil_range = Valanginian-Maastrichtian<br />~{{fossil range|140|70}} | type_species = '''''Protolamna sokolovi''''' | type_species_authority = Cappetta 1980 }}
'''''Protolamna''''' is an extinct genus of large mackerel shark from the Cretaceous Period.<ref name=":0">{{Cite journal|last1=Kriwet|first1=Jürgen|last2=Klug|first2=Stefanie|last3=Canudo|first3=José I.|last4=Cuenca-Bescos|first4=Gloria|date=October 2008|title=A new Early Cretaceous lamniform shark (Chondrichthyes, Neoselachii)|journal=Zoological Journal of the Linnean Society|language=en|volume=154|issue=2|pages=278–290|doi=10.1111/j.1096-3642.2008.00410.x|doi-access=free}}</ref> ''Protolamna'' fossils indicate gigantism evolved early on in the history of lamniforms.
== Fossil record == ''Protolamna'' is likely one of the most ancient lamniformes, known from as early as the Valanginian age of Early Cretaceous (ca. 140 Ma).<ref name=":1">{{Cite journal |date=2019-03-01 |title=A new lamniform shark Protolamna ricaurtei sp. nov. from the Lower Cretaceous of Colombia |url=https://www.sciencedirect.com/science/article/abs/pii/S0195667118303628 |journal=Cretaceous Research |language=en-US |volume=95 |pages=336–340 |doi=10.1016/j.cretres.2018.12.007 |issn=0195-6671}}</ref> It appears to have had a cosmopolitan distribution throughout its geologic range, with fossils found on every continent except Antarctica.<ref name=":1" />
== Paleobiology == ''Protolamna'' is known from isolated teeth, and a partial dentition associated with an articulated vertebral column.<ref name=":2">{{Cite journal |date=2026-02-01 |title=A large lamniform shark from the Aptian of Villa de Leiva (Boyacá, Colombia), based on the first Lower Cretaceous shark specimen preserving both teeth and vertebrae |url=https://www.sciencedirect.com/science/article/abs/pii/S019566712500134X |journal=Cretaceous Research |language=en-US |volume=178 |article-number=106211 |doi=10.1016/j.cretres.2025.106211 |issn=0195-6671|url-access=subscription }}</ref> Despite having small teeth (typically about 2 cm in size), from these more substantial remains, researchers have estimated a total length greater than {{Convert|6|m|ft|sp=us}}.<ref name=":2" /> This makes ''Protolamna'' the oldest-known gigantic lamniform.
From associated dermal denticles, researches have hypothesized that ''Protolamna'' was a pelagic-adapted predator that occupied near-shore environments.<ref name=":2" /> As a slow but active swimmer with a tearing type dentition, it likely preyed on bony fishes, small sharks, squids, and crustaceans in its environment.
== Species == Seven species are currently attributed to this genus, including the following:<ref name=":0" /> * ''P. borodini'' (Maastrichtian, New Jersey) * ''P. carteri'' (Cenomanian, Texas) * ''P. compressidens'' (Turonian-Coniacian, Belgium, France, Texas) * ''P. gigantea'' (Cenomanian, Minnesota) * ''P. ricaurtei'' (Barremian-Aptian Paja Formation, Colombia)<ref name=":1" /> * ''P. roanokeensis'' (Albian, Texas) * ''P. sokolovi'' (Aptian-Albian, Russia)
== References == {{Reflist}}
=== Bibliography === * {{citation |last1=Carrillo Briceño |first1=Jorge D. |last2=Parra |first2=Juan |last3=Luque |first3=Javier |year=2019 |title=A new lamniform shark ''Protolamna ricaurtensis'' sp. nov. from the Lower Cretaceous of Colombia |url=https://www.sciencedirect.com/science/article/pii/S0195667118303628 |journal=Cretaceous Research |volume=95 |pages=336–340 |doi=10.1016/j.cretres.2018.12.007 |bibcode=2019CrRes..95..336C |access-date=2019-03-12|doi-access=free }}
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Category:Prehistoric Lamniformes Category:Lamniformes Category:Prehistoric shark genera Category:Cretaceous fish of Europe Category:Fossils of Belgium Category:Fossils of France Category:Fossils of Russia Category:Cretaceous fish of North America Category:Fossils of the United States Category:Cretaceous fish of South America Category:Cretaceous Colombia Category:Fossils of Colombia Category:Paja Formation Category:Fossil taxa described in 1980 Category:Cretaceous sharks
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