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Leiorhynchoidea
Classification
Phylum:
Brachiopoda
Class:
Rhynchonellata
Order:
Rhynchonellida
Superfamily:
Pugnacoidea
Family:
Petasmariidae
Formal Genus Name and Reference:
Leiorhynchoidea CLOUD, 1944, p. 57
Type Species:
L. schucherti, OD
Images
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Fig. 809, 2a-d. *L. schucherti, Wordian, southwestern Coahuila, Las Delicias, Mexico, $a-c$, holotype, dorsal, ventral, and lateral views, x1$, $d$, Plasticine cast of dorsal interior mold, x2$ (Cloud, 1944), Fig. 809, 2e-j. L. amygdaloidea Cooper & Grant, Guadalupian, Word Formation, Glass Mountains, Texas, USA, $e-h$, holotype, dorsal, ventral, anterior, and lateral views, x1$, $i$, paratype, ventral valve interior, x2, j$, paratype, oblique view of dorsal valve interior, x2.6$ (Cooper & Grant, 1976a)
Synonyms
Geographic Distribution
North America, eastern Siberia
Age Range
Beginning Stage in Treatise Usage:
Lower Carboniferous (lower Namurian)
Beginning International Stage:
Serpukhovian
Fraction Up In Beginning Stage:
0
Beginning Date:
330.34
Ending Stage in Treatise Usage:
Upper Permian (Wordian)
Ending International Stage:
Wordian
Fraction Up In Ending Stage:
100
Ending Date:
264.34
Description
Large, subcircular to elongate oval, biconvex profile, gentle lateral and anterior slopes. Beak erect, delthyrium open apically, conjunct deltidial plates. Fold and sulcus weak, from umbones, anterior commissure uniplicate, tongue low, serrate. Costae low, few, rounded, weak on fold and in sulcus, very weak on flanks. Dental plates short, slightly convergent ventrally, ventral muscle field an elongate triangle expanding anteriorly. Dorsal median septum moderately strong, long, septalium short, dorsal muscle field narrow, crura long, ventrally curved, tips horizontally flattened.