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Planalvus gibberosa
Taxonomy
Planalvus gibberosa was named by Carter (1971). Its type specimen is UI X-3435, a shell, and it is a 3D body fossil. Its type locality is UI locality Z-1F, Eagle City Ls, Hampton Fm, Marshall Co, Iowa, which is in a Kinderhookian shallow subtidal limestone/limestone in the Hampton Formation of Iowa.
Synonymy list
| Year | Name and author |
|---|---|
| 1971 | Planalvus gibberosa Carter pp. 249 - 250 figs. pl. 1 f. 1-2; pl. 2 f. 12-41 |
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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.
†Planalvus gibberosa Carter 1971
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| J. L. Carter 1971 | Shell small for the subfamily; unequally biconvex, the brachial valve being much more inflated than the pedicle valve; longitudinally subellipsoidal to subcircular in outline, rarely wider than long; greatest width attained near midlength or slightly posterior to midlength; profile subovate; hinge-line short, curved, subterebratulid; cardinal extremities well rounded; fold and sulcus weakly developed in adult shells only; growth varices irregularly spaced; surface finely lamellose, the lamellae being finely striated and anteriorly fringed with very fine spines.
Pedicle valve thick-shelled, moderately to weakly and evenly convex in lateral profile; beak inconspicuous, with a small curved notch formed by the pedicle foramen; delthyrium almost completely filled by the dorsal umbo; beak ridges subangular, forming flattened pseudoareas on either side of the foramen; sulcus, if present, broad and shallow, giving the anterior portion of the shell a sublingual outline in many shells. Pedicle valve interior lacking dental plates, with a moderately impressed muscle field posteriorly; teeth large, blunt. Brachial valve thinner-shelled than pedicle valve; gibbous; much more inflated than the pedicle valve; most strongly convex in the umbo but nearly evenly curved in lateral profile; dorsum very high, the flanks sloping rapidly to the lateral margins but not forming an actual fold; beak well developed, incurved into the delthyrium of the pedicle valve. Brachial valve interior with large nonperforate ventrally concave cardinal plate that bends posterodorsally to unite with the floor of the valve between stout socket ridges; posterior edges of cardinal plate on either side of the dorsal beak slightly recurved, forming two low flanges that may fuse medially to form a small perforation (however, this perforation is in no way homologous with the visceral perforation in Composita, Cleiothyridina, or Athyris); crural bases arise either on the outer anterior edge of the cardinal plate or on the inner anterior edges of the socket ridges (this is essentially a histological problem and can best be handled with thin section techniques applied to calcareous or essentially unaltered specimens); brachidial structures unknown; low myophragm present in posterior third of valve. |
Measurements
No measurements are available
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| Source: subo = suborder, c = class, p = phylum, uc = unranked clade | |||||
| References: Nesnidal et al. 2013, Aberhan et al. 2004 | |||||
Age range: Kinderhookian or 358.90000 to 352.00000 Ma
Collections (4 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Kinderhookian | USA (Iowa) | Planalvus gibberosa (type locality: 62482) | |
| Tournaisian | USA (Iowa) | Planalvus gibberosa (141604 141610 141611) |