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Morphology Ecology and taphonomy   Age range and collections

Bilobia

Strophomenata - Strophomenida - Leptestiidae

Synonymy list
YearName and author
1956Bilobia Cooper pp. 760 - 761
1977Bilobia Mitchell
2000Bilobia Williams et al. p. 331
2002Bilobia Sepkoski, Jr.
2017Bilobia Madison pp. 369 - 370

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Eutriploblastica
Neotriploblastica
Eucoelomata
superphylumLophotrochozoa
Lophophorata
RankNameAuthor
phylumBrachiopodaCuvier 1805
subphylumRhynchonelliformeaWilliams et al. 1996
classStrophomenataWilliams et al 1996
orderStrophomenidaOpik 1934
superfamilyPlectambonitoideaJones 1928
familyLeptestiidaeOpik 1933
genusBilobia

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
G. A. Cooper 1956Shells small, concavo-convex, with the pedicle valve tumid ; cardinal extremities auriculate ; anterior commissure sulcate ; surface multicostellate ; a few strong costellae standing out in a field of very fine costellae.

Pedicle valve with deeply impressed large muscle field ; diductor scars elongate, divergent; adductor field oval in outline, deeply impressed, separating the posterior ends of the diductors. Teeth thick ; dental plates stout ; umbonal cavities filled by callus; dental plates extended as stout ridges around outside margin of muscle field. Vascula media short and thick, bifurcating into a larger inner branch and a small, shorter outer branch. Interarea curved, longer than the one on the brachial valve, hypercline. Pseudodeltidium short.

Brachial interior with strongly bilobed visceral disk, lobes triangular to rounded and the seat of attachment of the adductor muscles. Lobes with elevated rims on inside ; rims extending nearly to cardinal process. Lobes separated by a high, thin median septum extending to about the middle. Brachial processes short and small ; cardinal process with short, stout shaft bearing 3 ridges on the myophore face, a median elevated ridge and lateral lower ridges.
A. A. Madison 2017Shell strongly concavoconvex, subtriangular in outline, with maximum width at posterior margin. Ornamentation consists of ribs of two orders. Pseudodeltidium rudimentary or absent; chilidium present; teeth large and doubled; dental plates long; denticles along posterior margin may be developed. Muscle field of ventral valve consists of large, deeply impressed and well bordered diductor scars; adductor scars may be absent in some species; wide septum composed of fused tubercles may present. Cardinal process high, cleft, with trifid myophore; bema with undercut anterior margin, divided into two parts, with septum in the middle. Platform (or diaphragm) variously developed.