Chlamys branneri (Arnold, 1906)
ARNOLD, R. 1906. The Tertiary and Quaternary pectens
of California. United States Geological Survey Professional Paper, 47: 1-264,
pls. 1-53. [p. 55, pl. 3, figs. 9-11]
1906 Pecten (Chlamys) branneri Arnold, 1906 [partim]
R. Arnold, 1906, plate 3.
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«Description.— Adult shell averaging about 80 millimeters in altitude, higher than long, equivalve, slightly convex, and equilateral, except for ears; sides only slightly concave above; base regularly rounded below. Right valve with from 20 to 22 prominent, narrow, more or less scaly or spiny ribs, which in the adults are sometimes medially sulcated or dichotomous; interspaces generally much broader than the ribs, channeled and usually containing a spiny or scaly intercalary rib; whole surface sculptured by imbricating incremental lines, often also by microscopic reticulations; hinge line about two-thirds length of disk; anterior ear much produced and sculptured by 6 to 10 imbricated ridges, which are separated by equally wide reticulated interspaces; byssal notch profound; posterior ear about three-fifths length of anterior, and sculptured similarly. Left valve similar to right.
Dimensions.— Alt. 65 mm.; long. 58 mm.; hinge line 40 mm.; diameter 14 mill.; umbonal angle 83°. This species varies considerably in the degree of importance of the minor sculpture, such as reticulation, imbrication, and size of the sulcations and intercalaries. Although unquestionably allied to the Chlamys group, it has larger posterior ears than other species of the group that have come under the writer's notice. P. branneri resembles P. islandicus in size, outline, and general sculpture, but is distinguishable by having only about one-half as many ribs and much larger posterior ears. So far as is known, P. branneri is confined to the lowest horizon of the Miocene and top of the Oligocene. It is very abundant at the type locality, Tuff Hill, near Stanford University. One large right valve was also obtained from the fine sandstone immediately overlying the San Lorenzo shale series (Oligocene) in Twobar Creek, near the town of Boulder Creek, Santa Cruz County. The type, like all of the known specimens of the species, is a mold, and is now in the collection of the department of geology, Leland Stanford Junior University. Named in honor of Dr. J. C. Branner, professor of geology in that institution. RANGE.
Miocene (lower). Tuff Hill, Stanford University, Santa Clara County (Branner; J. P. Smith; Arnold).
Oligocene (upper) or Miocene (lower). Twobar Creek, near Boulder Creek, Santa Cruz County (Newson; Arnold).» RALPH ARNOLD, 1906
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«[specimen -of Pecten (Chlamys) branneri Arnold- from upper Oligocene Vaqueros Sandstone at Twobar Creek, near Boulder Creek, Santa Cruz County, collected by Newsom and Arnold is V. alexclarki, LSJU accession no. 4902].
(...) Addicott (1973) compared V. alexclarki to Chlamys branneri (Arnold, 1906); he found the latter equivalved with auricles having 6 to 10 radials. Fine macro sculpture is similar. Vertipecten alexclarki is early to early middle Oligocene in age; C. branneri is middle Miocene.» SMITH, J. T. 1991. Cenozoic Giant Pectinids from California and the Tertiary Caribbean Province: Lyropecten, "Macrochlamis", Vertipecten, and Nodipecten species. United States Geological Survey Professional Paper, 1391: v, 155p. , figs. 1-18, pls. 1-38. [p. 77]
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«The sculpture of the right valve of Chlamys branneri (Arnold, 1906, p. 55-56, pl. 3, figs. 9-11), a middle Miocene species from the eastern foothills of the Santa Cruz Mountains, is similar to that of the Vertipecten alexclarki. In fact, some workers (Kleinpell, 1938; Stinemeyer and others, 1959; Foss and Blaisdell, 1968) identified C. branneri from the Wygal Sandstone Member. Although the type material of C. branneri is poorly preserved, it is an equivalved species and, therefore, is properly assigned to Chlamys and not to the subsequently proposed genus Vertipecten, which is characterized by a relatively flat right valve and a convex left valve (see pl. 1, fig. 10). Other differences are the similar sculpture of both valves of C. branneri, the lack of
an accentuated medial rib on the left valve, and the greater number of radial ribs on the auricles of that species 6 to 10 rather than 5. It is possible that a specimen, or specimens, identified by Arnold (1906, p. 56) as C. branneri from the lower part of what is now mapped as Vaqueros Sandstone (Brabb, 1964) on Twobar Creek in the Santa Cruz Mountains, may represent V. alexclarki n. sp. The material is from rocks of approximately the same age. C. branneri, on the other hand, is from unnamed rocks of middle Miocene age from Coyote Hills near the Stanford University campus (Dibble, 1966).» ADDICOTT, W. O. 1973. Oligocene molluscan biostratigraphy and paleontology of the lower part of the Type Temblor Formation, California. United States Geological Survey Professional Paper, 791: 1-48, pls. 1-9. [p. 26]
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«Pecten branneri Arnold (1906) is in all probability equivalent to P. (Chlamys) sespeensis Arnold. Only poorly preserved casts were figured and described and these are identical with P. sespeensis in all discernible characters. Forms found north of Lynch's Mountain, Monterey County, have usuaUy been referred to P. branneri, while in that vicinity P. sespeensis is commonly reported. P. sespeensis has been collected from localities at which "P. branneri" has been reported.»
LOEL, W. & W. H. COREY. 1932. The Vaqueros formation, lower Miocene of California I. Paleontology. University of California Publications, Bulletin of the Department of Geological Sciences, 22 (3): 31-410, pls. 4-65. [p. 197]
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