{{Automatic taxobox | fossil_range ={{Fossil range|Callovian|Santonian}} | image = Plesioteuthis_prisca_01.jpg | image_caption = ''Plesioteuthis prisca'' | display_parents = 2 | taxon = Plesioteuthididae | authority = Naef, 1921 | subdivision_ranks = Genera | subdivision = ''Boreopeltis''<br /> ''Dorateuthis''<br /> ''Eromangateuthis''<br /> ''Nesisoteuthis''<br /> ''Paraplesioteuthis''<br /> ''Plesioteuthis''<br /> ''Rhomboteuthis''<br /> ''Romaniteuthis'' | synonyms = }}
'''Plesioteuthididae''' (sometimes shortened to '''Plesioteuthidae''') is an extinct family of cephalopods. Although they are definite members of Coleoidea, their exact placement within the group is contentious and still under debate.
== Classification == Historically believed to be allied with the squid and cuttlefish in Decapodiformes (sometimes known as Decabrachia), recent fossil finds indicate that they may be more closely related to vampire squid and octopuses, as the earliest branch of Octopodiformes (alternatively known as Octobrachia).<ref name=":0">{{Cite journal |last=Klug |first=Christian |last2=Fuchs |first2=Dirk |last3=Schweigert |first3=Günter |last4=Röper |first4=Martin |last5=Tischlinger |first5=Helmut |date=2015-11-01 |title=New anatomical information on arms and fins from exceptionally preserved Plesioteuthis (Coleoidea) from the Late Jurassic of Germany |url=https://doi.org/10.1007/s13358-015-0093-y |journal=Swiss Journal of Palaeontology |language=en |volume=134 |issue=2 |pages=245–255 |doi=10.1007/s13358-015-0093-y |issn=1664-2384}}</ref>
== Description == Their overall anatomy is highly squid-like, with elongated mantles that possessed fins at their ends. Some genera possessed two pairs of fins on their mantles, similar to other Mesozoic cephalopods such as ''Trachyteuthis'' and juvenile vampire squid. These fins either aided in stabilization or in propulsion for the animal.<ref name=":0" /> Unlike squid and cuttlefish, they do not appear to have any indication of having specialized feeding tentacles. Instead, they possess only eight arms with uniserial suckers. This makes them more similar to octopuses, vampire squid, and the extant Octopoteuthidae than any conventional squid.<ref name=":0" />
== Paleoecology == Similarly to extant squid in the order Myopsida, plesioteuthidids were fast and agile nearshore carnivores, such as the namesake ''Plesioteuthis''. Although many were rather small cephalopods, ''Eromangateuthis'' possessed an enormous gladius that suggests a total length of ~2 meters with the head and arms, easily making it the largest member of Plesioteuthididae.<ref>{{Cite journal |last=Fuchs |first=Dirk |date=2019-10-08 |title=Eromangateuthis N. Gen., A New Genus for a Late Albian Gladius-Bearing Giant Octobrachian (Cephalopoda: Coleoidea) |url=https://journals.ku.edu/paleocontributions/article/view/20295 |journal=Paleontological Contributions |language=en |issue=21 |pages=1–3 |doi=10.17161/1808.29619 |issn=1946-0279}}</ref> Smaller genera were likely highly important sources of food for other animals in their environments. One fossil of ''Plesioteuthis'' was found with a tooth from the pterosaur ''Rhamphorhynchus'' in its mantle, which likely broke off after it dropped the plesioteuthidid in a hunting attempt.<ref>{{Cite journal |last=Hoffmann |first=R. |last2=Bestwick |first2=J. |last3=Berndt |first3=G. |last4=Berndt |first4=R. |last5=Fuchs |first5=D. |last6=Klug |first6=C. |date=2020-01-27 |title=Pterosaurs ate soft-bodied cephalopods (Coleoidea) |url=https://www.nature.com/articles/s41598-020-57731-2 |journal=Scientific Reports |language=en |volume=10 |issue=1 |doi=10.1038/s41598-020-57731-2 |issn=2045-2322 |pmc=6985239 |pmid=31988362}}</ref>
== References == {{Reflist}}
== External links == * [https://archive.today/20130208210227/http://www.tonmo.com/forums/showthread.php?t=1591 TONMO Forums: Plesioteuthis] * [http://www.cosis.net/abstracts/EGU05/06376/EGU05-J-06376.pdf Morphology, feeding habits and phylogenic implications of the Cretaceous coleoid ''Dorateuthis syriaca'']
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Category:Prehistoric cephalopod families Category:Squid Category:Taxa named by Adolf Naef
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