Agerchlamys wunschae (Marwick, 1953)
MARWICK, J. 1953. Divisions and faunas of the Hokonui System (Triassic and Jurassic). New Zealand Geological Survey Paleontological Bulletin, 21: 1-141, pls. 1-17 (Corrigenda supplement: S1-S3). [p. 98, pl. 10, figs. 23, 24]
1953 Chlamys (Camptochlamys) wunschae Marwick, 1953
J. Marwick, 1953, plate 10.
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«Shell fairly large, evidently thin. Right valve gently inflated, left valve a little more so. Ears very unequal, right anterior extremely long and having a deep byssal notch, posterior ones obliquely triangular, all well separated from the disk by a definite channel. Sculpture of numerous, fine, rounded, radial ribs, with rather wider interspaces, crossed by still more numerous concentric fine lamellae, stronger in the interspaces than on crossing the ribs and giving an imbricate appearance eqpecially distally. The number of ribs is difficult to state definitely as new secondaries, appearing in the interspaces, increase in strength and ultimately rival the primaries. On the holoyype at 8 mm. height there are about forty ribs with an additional eight or ten very weak secondaries; at 16 mm. height, the numbers have increased to about fifty-six and sixteen respectively, and the adult has about seventy and fifteen. At 8 mm. height the concentric ridges are about five per millimetre and in the adult two per millimetre. On the ears the concentric lamellae are very strong, making a regular trellis with the radials especially on the right anterior ear, and forming small nodes at the intersections. The rigltt ear has six radials, the top one well separated from the hinge margin. Very fine Camptonectes striation occurs on the holotype along both posterior and anterior dorsal margins of the disk, and on the posterior ear. On a few of the interspaces on the holotype and on most of them on paratypes are from three to six fine striae, not in the divergent "Camptonectes" pattern but parallel to the ribs.
Holotype.— N.Z. Geological Survey.
Height (estimated), 52 mm.; length, 51 mm.; inflation (holotype, right valve), 5 mm. Localities.— G.S. 3203, Wyndham S.D., Southland, rapids in Wyndham River, half a mile east of Glenham Road, Miss P. Sandys Wunsch coll., 1934 (type). G.S. 338, Hokonui S.D., bed 60, Flag Hill Series, tableland above One Tree Bluff, Otapiri Gorge, A. McKay (1878: 82). G.S. 146, Tautuku S.D., Tautuku Bay, South Otago. G.S. 3521 Wyndham S.D., Southland. G.S. 3344, Wyndham S.D., Rae's Quarry, Léonards Road. Stage.— Ururoan (upper Lias).» JOHN MARWICK, 1953
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«Agerchlamys Damborenea (Fig. 6.1a, k) includes late Triassic–Early Jurassic species known from circum-Pacific localities. During most of this time range, but at least during the Pliensbachian, the genus had a clear bipolar distribution, with records from NE Russia, New Zealand, and west-central Argentina. Species of this genus are found in the Andes and in New Zealand in very fine-grained sediments, from marls to tuffaceous siltstones, but never in laminated dark mudstones. Although locally abundant in certain beds, they were not widespread, and at least A. wunschae (Marwick) seems to have been a stenotopic species limited to very low-energy but well-oxygenated environments. It was a byssally attached pectinid, and it was never associated to thick-shelled epifaunal bivalves or corals, but usually occurs with sponge spicules instead, probably sponges were their substrate (Damborenea 1993, 2002a and references therein).»
DAMBORENEA, S. E., J. ECHEVERRÍA & S. ROS-FRANCH. 2013. Southern Hemisphere Palaeobiogeography of Triassic-Jurassic marine bivalves. In K. Hamilton et al. (Eds.), SpringerBriefs Seaways and Landbridges: Southern Hemisphere Biogeographic Connections Through Time, 139 p.,figs. 1-6. [p. 126]
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Agerchlamys wunschae (Marwick); S. E. Damborenea, J. Echevarría & S. Ros-Franch, 2013, Southern Hemisphere Palaeobiogeography of Triassic-Jurassic marine bivalves, figure 6.1 k.
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«Remarks: This is the first record of the genus from Mexico. A. wunschae has been extensively described recently by Damborenea (2002) and no further description is needed here. Similar to the Chilean specimens described by Aberhan (1994), the Mexican representatives lack the fine divaricate striae reported by Damborenea (1993, 2002) in specimens from the Pliensbachian of Argentina and New Zealand.
Taylor and Guex (2002, p. 14, pl. 1, figs. 1-4, 8-11; pl. 4, figs. 1-3) described Agerchlamys boellingi, a new species from the upper Hettangian of Oregon. This species has a great similarity to A. wunschae, but differs in its left valve being more inflated than the right one, and its posterior auricle being more than half the length of the anterior auricle.» SCHOLZ, A., M. ABERHAN & C. M. GONZÁLEZ-LEÓN. 2008. Early Jurassic bivalves of the Antimonio terrane (Sonora, NW Mexico): Taxonomy, biogeography, and paleogeographic implications. Geological Society of America, Special Papers, 442: 269-312, figs. 1-17. [p. 286]
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Agerchlamys wunschae (Marwick, 1953); A. Scholz, M. Aberhan & C. M. González-León, 2008, Early Jurassic bivalves of the Antimonio terrane, figures 7C, 7D.
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