Leopecten macdonaldi (Olsson, 1922)
OLSSON, A. A. 1922. The Miocene of Nothern Costa Rica with notes on its general stratigraphic relations. Bulletins of American Paleontology, 9 (39): 1-460, pls. 1-32. [p. 198, pl. 16, figs. 1-2]
A. A. Olsson, 1922, plate 16.
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«Shell large, subcircular; ears of medium size and equal; left valve is slightly convex due to the middle of the shell being transversely humped or vaulted and a depressed zone follows on the inner slope of each of the raised dorsal submargins; the right valve is slightly but evenly convex; sculpture of the right valve consists of about 26, low ribs which widen out as they approach the ventral margins; their interspaces are at first nearly as wide as the ribs themselves but become only ½ or ⅓ as wide ventrally; the left valve has 21 or 22 narrow ribs and wider interspaces; on the dorsal submargins, the ribs are small and fade away; surface with fine, even, raised lines best seen on the left valve.
Length 106, height 97, semi-diameter 12 mm. 83 80 mm. The fragmentary Toro limestone at Gatun and Toro Point contains very few good fossils, although the rock itself is composed almost entirely of broken and ground fragments of shells and barnacles. Dall has described an Epitonium toroensis from the Toro Point limestone where it is fairly common. The Pecten MacDonaldi is found in the Toro limestone which caps the hills just west of the locks at Gatun. This species has much the same contour as the recent Pecten maximus Linne, from Europe. It is a larger species than the Pecten gatunensis Toula. Toro Limestone. Gatun, west of the locks.» AXEL ADOLPH OLSSON, 1922
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«Leopecten gatunensis differs from L. macdonaldi in the trend of the free margins of the posterior auricles, which are less obtuse relative to the dorsal margin in the latter. The left auricles of L. gatunensis lack radial costae, but these are invariably present in L. macdonaldi. The latter species also has lower ribs on the disk and a more flaring shape.»
WALLER, T. R. 2011. Neogene Paleontology of the Northern Dominican Republic. 24. Propeamussiidae and Pectinidae (Mollusca: Bivalvia: Pectinoidea) of the Cibao Valley. Bulletins of American Paleontology, 381: 1-197, pls. 1-18. [p. 109]
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«Two left valves of a true Pecten occur in the San Fernando beds. They are very flat, the umbones sunk below the level of the slightly elevated dorsal margins of the disk. The submargins are wide for so flat a shell and sculptured with incrementals only. The ears are small, narrow, obscurely lirate, incrementally scabrous. The 20 radials are broadly and evenly rounded, abruptly rising from the flat interradial areas. There are no defined crurae in the left valve. The muscle impression is small, sunken, and almost entirely within the antero-dorsal quadrant. The crenations of the inner ventral margins are deep, and the ribs in reverse are traceable more than half way up to the dorsal margins.
DIMENSIONS OF FIGURED LEFT VALVE: Height, 44 millimeters; width, 47 millimeters. FIGURED SPECIMEN, A LEFT VALVE: U. S. Nat. Mus. 495022. Both left valves are from the Guajalote formation at U.S.G.S. sta. 13588 (W_30), 620 meters N. 55° W. from the church tower in San Fernando, Tamaulipas. Olsson's species is double the size of the Mexican shell and has about 6 more ribs. The closely related form figured by Mansfield from the lowest Choctawhatchee is 58 millimeters high and 60 millimeters wide. The number of ribs is the same as that of the Mexican valves, and the ears are similar, but the submargins are wider. The Mexican form is probably distinct from both the Costa Rican and the Floridian species, but the resemblance may indicate a genetic relationship.» GARDNER, J. 1945. Mollusca of the Tertiary formations of northeastern Mexico. Geological Society of America Memoirs, 11: 1-332, pls. 1-27. [p. 64]
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Pecten (Pecten) sp. cf. P. (P.) macdonaldi Olsson; J. Gardner, 1945, Mollusca of the Tertiary formations of northeastern Mexico, plate 11, figures 1, 3.
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