{{Short description|Extinct family of gastropods}}{{Hatnote|Not to be confused with Bellerophontidae, an extinct family of unrelated molluscs}}{{Automatic_taxobox | fossil_range = {{Fossil range|Middle Triassic|Albian}} | image = Oxygyrus keraudrenii 3.png | image_caption = The shell of ''Oxygyrus keraudrenii'', a species closely resembling ''Bellerophina'' | taxon = Bellerophinidae | authority = Destombes, 1984 | subdivision_ranks = Genera | subdivision = }}
'''Bellerophinidae''' is an extinct family of sea snails, marine gastropod molluscs in the clade Littorinimorpha.<ref>{{cite journal |author1=Bouchet, P. |author2=Rocroi, J.-P. |name-list-style=amp | year = 2005 | title = Classification and Nomenclator of Gastropod Families | journal = Malacologia | volume =47 | issue = 1–2 | pages = | doi = }}</ref> It is considered by WoRMS to contain 2 genera; ''Bellerophina'' and ''Freboldia''.<ref name=":0">{{Cite web |title=WoRMS - World Register of Marine Species - Out of scope |url=https://www.marinespecies.org/aphia.php?p=taxdetails&id=833900#sources |access-date=2026-04-03 |website=www.marinespecies.org}}</ref> Despite ''Bellerophina'' being the namesake of this family, more recent research has moved the genus to the family Atlantidae on the basis of similar shell morphology to the extant genus ''Oxygyrus'', although the exact relationship remains unclear.<ref name=":3">{{Cite journal |last1=Wall-Palmer |first1=Deborah |last2=Janssen |first2=Arie W. |last3=Goetze |first3=Erica |last4=Choo |first4=Le Qin |last5=Mekkes |first5=Lisette |last6=Peijnenburg |first6=Katja T. C. A. |date=2020-09-21 |title=Fossil-calibrated molecular phylogeny of atlantid heteropods (Gastropoda, Pterotracheoidea) |journal=BMC Evolutionary Biology |language=en |volume=20 |issue=1 |pages=124 |doi=10.1186/s12862-020-01682-9 |doi-access=free |issn=1471-2148 |pmc=7507655 |pmid=32957910 |bibcode=2020BMCEE..20..124W }}</ref>
== Description == Both genera in Bellerophinidae share small, thin, rounded, and bilaterally symmetrical aragonitic shells.<ref name=":1">{{Cite journal |last1=Nützel |first1=Alexander |last2=Schneider |first2=Simon |last3=Hülse |first3=Peter |last4=Kelly |first4=Simon R.A. |last5=Tilley |first5=Laura |last6=Veit |first6=Reinhart |date=June 30, 2016 |title=A new Early Jurassic gastropod from Ellesmere Island, Canadian Arctic - an ancient example of holoplanktonic gastropods |url=https://www.researchgate.net/publication/348382899 |journal=Bulletin of Geosciences |volume=91 |issue=2 |pages=229–242 |doi=10.3140/bull.geosci.1597 |via=Research Gate}}</ref> ''Bellerophina'' is morphologically similar to and likely closely related to the Atlantids, with their shared adaptations and miniscule maximum shell size of 6-8mm making it probable that both genera in Bellorophinidae would have shared their lifestyle as active holoplanktonic predatory micromolluscs.<ref name=":3" /><ref name=":1" />
=== †''Freboldia'' <small>d'Orbigny, 1843</small> === The genus ''Freboldia'' contains two species; ''F. carinii'', and ''F. fluitans''.<ref name=":0" /><ref name=":2">{{Cite journal |last1=Pieroni |first1=Vittorio |last2=Nützel |first2=Alexander |date=2020-10-28 |title=Freboldia carinii sp. nov. from the Middle Triassic Brembana Valley (Esino Limestone, Southern Alps, Italy) – possibly the oldest known holoplanktonic gastropod |url=https://www.schweizerbart.de/papers/njgpa/detail/298/96655/Freboldia_carinii_sp_nov_from_the_Middle_Triassic_ |journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |volume=298 |issue=1 |language=en |pages=9–15 |doi=10.1127/njgpa/2020/0929 |bibcode=2020NJGPA.298....9P |url-access=subscription }}</ref> It was named after the late Hans Frebold, a German paleontologist who was instrumental in advancing paleontology in the Arctic.<ref name=":1" /> ''F. fluitans'' dates to the Early Jurassic (Late Pliensbachian/Early Toarcian) of Ellesmere Island.<ref name=":1" /> The shells of ''F. fluitans'' are small, reaching at most 8 mm in diameter and 6.3 mm in height, and thin, ranging from 25-40 µm in thickness.<ref name=":1" /> The shape is described as "inflated, globular, planispiral, bilaterally symmetrical, with deep umbilici."<ref name=":1" /> The aperture is kidney-shaped, being taller than it is wide when viewed from the side, with the inner lip curving inwards whilst the outer lip curves outwards.<ref name=":1" /> Mature shells are smooth except for straight growth-lines that run parallel to the shell axis at the edges and touch the umbilicus at a single point, whilst young shells have vague spirals and tubercles.<ref name=":1" /> A presumed larval shell under 1 mm in size has very thin indents along the whorls lacking in older individuals, which would be unique among known holoplanktonic gastropods.<ref name=":1" /> The bilateral symmetry of the shell makes it difficult to tell which direction the whorls coil in.<ref name=":1" /> ''F. carinii'' is known from the Middle Triassic of the Brembana Valley, very closely resembling the other species except in being much older; if it shared the proposed lifestyle of ''F. fluitans'', it would be the oldest known holoplanktonic gastropod.<ref name=":2" />
=== †''Bellerophina'' <small>Nützel & S. Schneider, 2016</small> === The genus ''Bellerophina'' has been proposed to contain up to 3 species, including ''B. minuta, B. recens,'' and ''B. vibrayi''.<ref name=":0" /> However, the classification of ''B. recens'' is problematic, and ''B. vibrayi'' is a synonym of ''B. minuta''.<ref name=":0" /> ''B. minuta'' is known from the Early Cretaceous (Albian) of England, originally being incorrectly classified as ''Ammonites minutus.''<ref name=":0" /><ref name=":4">{{Cite book |last1=Sowerby |first1=James |url=https://www.biodiversitylibrary.org/item/210430 |title=The mineral conchology of Great Britain; or, Coloured figures and descriptions of those remains of testaceous animals or shells, which have been preserved at various times and depths in the earth / By James Sowerby. |last2=Farey |first2=John |last3=Sowerby |first3=James de Carle |publisher=Printed by B. Meredith [etc.] |year=1812 |volume=1 |location=London |pages=116–117 |language=en |doi=10.5962/bhl.title.14408 |archive-url=http://web.archive.org/web/20250425140544/https://www.biodiversitylibrary.org/item/210430 |archive-date=2025-04-25}}</ref> The shell is small, thin, rounded, bilaterally symmetrical, up to 6 mm in diameter, and has a deep umbilicus.<ref name=":3" /><ref name=":1" /><ref name=":4" /> It is ornamented with a grid of raised lines following the curvature, closely resembling larval ''Oxygyrus inflatus''; ''Freboldia'' also closely resembles ''Bellerophina'' in shape but lacks the lines.<ref name=":3" /><ref name=":1" />
== References == {{Reflist}}
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Category:Gastropod families Category:Littorinimorpha
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