Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 9
... posteriorly and is crossed by growth lirae that give it a scaly corded appearance . The flanks are ornamented with up to 28 pronounced , subconcentric costae that are slightly narrower than the interspaces on the posterior half of the ...
... posteriorly and is crossed by growth lirae that give it a scaly corded appearance . The flanks are ornamented with up to 28 pronounced , subconcentric costae that are slightly narrower than the interspaces on the posterior half of the ...
Page 13
... posteriorly meeting the marginal carina at an angle of c . 30 ° . Except for the posterior few ribs , most flank costae curve strongly forwards to meet the anterior and anteroventral commissures almost at right angles . All flank costae ...
... posteriorly meeting the marginal carina at an angle of c . 30 ° . Except for the posterior few ribs , most flank costae curve strongly forwards to meet the anterior and anteroventral commissures almost at right angles . All flank costae ...
Page 39
... posterior set . The anterior costae are as wide as or narrower than the interspaces ; those closest to the umbo are coarsely tuberculate throughout . Posteriorly , however , the coarse rounded tuberculation is increasingly restricted to ...
... posterior set . The anterior costae are as wide as or narrower than the interspaces ; those closest to the umbo are coarsely tuberculate throughout . Posteriorly , however , the coarse rounded tuberculation is increasingly restricted to ...
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Common terms and phrases
Algoa Basin Anditrigonia antecarinal sulcus anterior commissure anterolateral shoulder anteroventrally Apiotrigoniinae Bivalvia broad chevrons coarse commissure comprises convex Cooper Cretaceous Description Shell Diagnosis elongate escutcheon carina faunas finely crenulated flank costae flank ornament genus growth rugae growth striae Hauterivian Hoepen holotype inflated anteriorly interspaces Iotrigonia irregular Kobayashi kraussi Kitchin lanceolate large maximum length Lateral view lectotype left valve longitudinal groove Megatrigoniacea moderately Myophorella Myophoriidae Nakano neotype nepionic stages Neumayr nodate Nototrigoniinae opisthogyrous beaks Paranditrigonia paratypes persisting to maturity phyletic Port Elizabeth Museum posterior set posterodorsal margin Poulton Pterotrigonia radial costellae radial ornament Rennie respiratory margin Reyes ribs right valve rostrate shallowly concave shell length Skwarko smooth South African Museum Steinmanella herzogi Goldfuss straight strongly oblique subconcentric subfamily Sundays River Superfamily synonymy Tashiro Tithonian transverse costellae transverse ornament Trigonia Trigoniacea Trigoniinae trigonioid tubercles Type species Upper Valanginian V-shaped Valanginian vau Sharpe ventral margin ventricosa Krauss Yaadia