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Placunopsis

Bivalvia - Pectinida - Anomiidae

Taxonomy
Placunopsis was named by Morris and Lycett (1853) [Sepkoski's age data: Tr Olen-u T Dani Sepkoski's reference number: 545,1061]. It is not extant.

It was assigned to Plicatulidae by Marwick (1953); to Placunidae by Ronchetti (1970); to Terquemiidae by Vokes (1980); to Pterioida by Sepkoski (2002); and to Anomiidae by Todd and Palmer (2002) and Lazo and Damborenea (2011).

Synonymy list
YearName and author
1853Placunopsis Morris and Lycett
1953Placunopsis Marwick p. 101
1970Placunopsis Ronchetti p. 56
1980Placunopsis Vokes p. 59
2002Placunopsis Sepkoski, Jr.
2002Placunopsis Todd and Palmer
2011Placunopsis Lazo and Damborenea p. 730

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Protostomia
Spiralia
Schizocoela
phylumMollusca
classBivalvia
Eubivalvia
subclassAutobranchia(Groblen 1894)
infraclassPteriomorphia(Beurlen 1944)
RankNameAuthor
OstreomorphiFerussac 1822
OstreioniFerussac 1822
OstreataFerussac 1822
superorderOstreiformiiFerussac 1822
orderPectinida(Gray 1854)
suborderAnomiidinaGray 1854
AnomioideiGray 1854
AnomioiteiGray 1854
superfamilyAnomioideaRafinesque 1815
familyAnomiidaeRafinesque 1815
genusPlacunopsisMorris and Lycett 1853

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Diagnosis
ReferenceDiagnosis
J. A. Todd and T. J. Palmer 2002Medium-sized (< 60mm high), subcircular, thin-shelled and compressed anomiid. RV extremely thin, closely adpressed to substratum, with byssal notch (open foramen) surrounding an uncalcifed byssal plug;
medium sized adductor scar adjacent to postero-ventral margin of foramen. LV exterior with very fine to moderately strong radiating riblets. Interior with shallowly arched crus with adjoining buttress extending posteroventrally for length of foramen. Two prominent muscle scars present; a moderate-sized posterior pedal (byssal) retractor scar at 25±50 per cent height; touching at its posteroventral edge a smaller adductor scar. Also present is a minute anterior pedal retractor scar. Shell structure: RV, outer shell layer
extremely thin, prismatic; inner shell layer of cross lamellar aragonite: LV, outer shell layer of foliated calcite; extensive cross lamellar aragonite inner shell layer, extending 80±90 per cent of distance to ventral margin.