Vertipecten perrini (Arnold, 1906)
ARNOLD, R. 1906. The Tertiary and Quaternary pectens of California. United States Geological Survey Professional Paper, 47: 1-264, 53 pls. [p. 80, pl. 14, figs. 1, 1a; pl. 15, fig. 1]
1906 Pecten (Lyropecten) perrini Arnold, 1906
R. Arnold, 1906, plates 14, 15.
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«Description.— Shell averaging about 150 millimeters in altitude, somewhat longer than high, inequivalve. equilateral, of medium thickness, ventricoso, and with smooth margins; base regularly rounded; sides sloping and decidedly concave above. Right valve nearly flat, with about 23 unequal, narrow, more or less rounded, and often prominently imbricated, radiating ribs, which are sometimes dichotomous; interspaces unequal, narrow, and occasionally ornamented by a small auxiliary riblet; surface sculptured by fine incremental lamellae which are much more prominent in some specimens than in others; hinge line about one-half length of disk; ears about equal in length; anterior ear wide, ornamented by concentric incremental sculpture; byssal notch wide and deep; posterior ear ornamented by several prominent, more or less imbricated radiating ridges, and concentric sculpture. Left valve quite prominently ventricose, otherwise similar to the right, except that the ribs seem to vary even more in relative size and spacing; anterior ear lacking notch, otherwise ears similar to those of the right valve.
Dimensions.— Alt. 150 mm.; long, (restored) 160 mm.; hinge line (restored) 80 mm.; diameter 55 mm. This is a most variable species, there being no two specimens sculptured in exactly the same manner in a series of over fifty specimens examined. The convexity of the valves is almost constant, the variable factors being the number and relative importance of the intercalary ribs, and the prominence of the incremental sculpture. The geologic range of P. perrini is from the lower to the middle (?) Miocene. It is found associated with Pecten magnolia, and other characteristic lower Miocene fossils between Morro and Toro creeks, San Luis Obispo County, while at Roblar, in the same county, it is found with P. discus, a species found usually in the Santa Margarita formation. The type, an imperfect specimen, of which both valves are figured, is from the lower Miocene between Morro and Toro creeks, San Luis Obispo County, and is now in the collection of the department of geology, Stanford University. Named in honor of Dr. James Perrin Smith, professor of paleontology at the Leland Stanford Junior Universitv. RANGE.
Miocene (middle?). Roblar, 12 miles from Paso Robles. and on ranch of W. F. Gillis, 10 miles southwest of Paso Robles, San Luis Obispo County (J. P. Smith).
Miocene (lower). Between Morro and Toro creeks, and on the Lenton ranch, between Morro and Old creeks, San Luis Obispo County (Fairbanks, R. Moran); 30 miles north of Santa Monica and 1 mile from the ocean. Ventura (?) County (R. E. Maynard); Pyramid Mountain, Greenhorn Mountains, Kern County (No. 12925, C. S. M. B.) (Watts).» RALPH ARNOLD, 1906
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«Holotype.— LSJU 13, two-valved adult specimen, 15.0 cm high, 16.0 cm long (restored) left valve deformed.
Type locality.— Southern Santa Lucia Mountains, San Luis Obispo County, Calif. North of Morro Bay, "***between Morro and Toro Creeks." Associated with Pecten [= "Macrochlamis"] magnolia. Early Miocene. The type area was not rediscovered until Hall and Prior (1975) mapped the Cayucos 15-minute quadrangle and worked out the regional stratigraphy. They considered the type locality to be in the Morro Bay North 7½-minute quadrangle at the knob just south of hill 1017 in sec. 4, T. 29 S., R. 11 E. (UCLA loc. 6204), in a lithic sandstone facies of the Vaqueros Formation; here the formation is 20-40 ft thick and older than at its type locality in Los Vaqueros Valley to the north. Lower "Vaqueros" Stage. Arnold named the species in honor of James Perrin Smith, Professor of Paleontology at Stanford University from 1892-1931, mentor and well-loved teacher of several generations of students. Description.— Right-valve flat, left-valve convex; length exceeds height. Left-valve beak projects slightly beyond hinge line. Auricles subequal, with flanged radial riblets. Byssal notch deep. Umbonal angle wide, 92-103º, varying with shell convexity. Ribs numerous, commonly bifurcated, and variable in widths and spacing. Right valves with about 28 ribs and riblets of at least three widths. Left valves with 22-23 coarsely imbricated ribs, interspaces with 1-3 scaly riblets. Juvenile shells commonly worn, ribs and riblets undifferentiated. Relatively few articulated specimens are present in collections; the best preserved specimen is the holotype. The largest specimen seen was incomplete; it is 19.7 cm high, 21.3 cm long (USGS loc. M4200, west of Paso Robles). Variability.— Too few specimens are available to evaluate variability, either between individuals or growth stages. Arnold (1906) noted considerable variation in "over 50 specimens examined," but this is more than twice the number of specimens I found in all the museum collections combined. Most specimens are very worn and incomplete. One specimen from the northern La Panza Range has unusually fine ribbing (USGS loc. M4737). Comparative notes.— Evolutionary trends of the California Vertipectens, two of which are closely related to V. perrini in a continuous phylogenetic progression, are shown in table 5. Transitional forms between V. yneziana and V. perrini and between V. perrini and V. kernensis (= V. nevadanus auctt.) cannot be separated from either end member. Vertipecten perrini is the first Vertipecten to attain a very large adult size, and to have a flat right valve and convex left valve typical of the genus. Vertipecten perrini commonly occurs with another giant pectinid, "Macrochlamis" magnolia, s.s., from which it differs in having a smooth hinge, valves unequal in profile, and more numerous, imbricated, rectangular ribs. Phylogenetic affinities.— Vertipecten perrini is a member of a well-documented phylogenetic series; it evolved by the middle Oligocene from V. yneziana and gave rise in the late Oligocene to V. kernensis (= V. nevadanus auctt.) (pl. 32). Vertipecten perrini is similar to the Pacific Northwest species Vertipecten lachenbruchi MacNeil, 1967 from the upper Acila shumardi zone of the Alaskan Peninsula (M1025) and the Shumagin Islands (USGS 5037). Vertipecten perrini from the La Panza Range (M4737) is perhaps closest in morphology to Alaskan specimens of V. lachenbruchi. Geographic distribution and stratigraphic occurrences.— Central and southern California, from the Santa Lucia and La Panza Ranges, central Temblor Range, San Emigdio Mountains, and Transverse Ranges. Representative occurrences: Vaqueros Formation, Junipero Serra Peak quadrangle. "The Indians," (LSJU accession no. 1758), 7 mi southwest of the type locality of the Vaqueros Formation in sec. 16, T. 21 S., S. 5E. Vertipecten perrini from here has the proportions, profiles, and ribbing of the holotype, LSJU-13, but specimens are poorly preserved; they are external molds lacking outer shell material. The Vaqueros Formation here is older than at the type locality. Addicott re-collected the locality (M6494) in 1975 and regarded the associated fossils as the same as those in the Wygal Sandstone Member of the Temblor Formation in the Temblor Range. They represent the unnamed stage of Addicott (1972), older than lower "Vaqueros" Stage. Vaqueros Formation, Santa Lucia Range, Adelaida 15-minute quadrangle. The "Lepidocyclina locality" of Schenck and Childs, 1942 (LSJU loc. 1155, specimen linking V. perrini and V. kernensis). Specimens collected singly in the 1890's from ranches west and southwest of Paso Robles. They lack detailed locality and stratigraphic data (for example, Gillis Ranch, LSJU accession no. 47629; G.W. Michaels Ranch, AMNH 11730; Lenton Ranch, between Morro and Old Creeks, GAS accession no. 9365). On modern geologic maps these localities are in lower beds of the Vaqueros Formation. Vaqueros Formation, Cypress Mountain 7½-minute quadrangle. V. perrini is common in rocks north of Santa Rosa Creek along the old highway between Cambria and Paso Robles. Near Oceanie Mine (Hall, oral commun., 1973); UCLA 6069 and 6070; San Simeon 15-minute quadrangle (LSJU accession no. 30261, between Carroll and McLoughlin Canyons). Vaqueros Formation, Morro Bay North 7½-minute quadrangle (Prior, 1974). Type locality of V. perrini, between Morro and Toro Creek (UCLA 6204) and in canyons to the north (abundant at UCLA 6205, 6206). It is present in a lithic and calcareous sandstone facies about 5 m above the base of the formation in this area. Outcrops are discontinuous; they contain numerous specimens of V. perrini and "Macrochlamis" magnolia, s.s. Between San Bernardo Creek and Little Morro Creek in sec. 14, T. 29 S., R. 11 E. (UCLA 6191, 6192). Specimens of V. perrini are worn but are similar to V. kernensis in rib sizes and spacing. The Vaqueros Formation may be slightly younger than at UCLA 6204, but the upper age limit is unknown because all of the Saucesian and part of the Zemorrian benthic foraminiferal stages are missing (Prior, 1974). Alegria Formation (Dibblee, 1950), Transverse Ranges. Transitional forms between V. perrini and V. yneziana: at UCMP B-7015, LSJU acc. no. 53256 (Hawley loc. 93, west-southwest of Las Cruces); also in Gaviota Canyon and Canada del Agua Caliente [Hawley label says "Turritella variola zone"]; LSJU accession no. 53251 (Hawley loc. 76, west of Cuarta Canyon), and UCSB 1561, Canada de Santa Anita. Middle part of the Gaviota Formation, Transverse Ranges. (Dibblee, 1950): LSJU specimen, Hawley loc. 68; poorly preserved transitional form between V. perrini and V. yneziana; UCMP A-4646, uppermost part of middle member of the Gaviota Formation, the Vertipecten is V. perrini with some features of V. yneziana. The foraminifers from here belong to the Refugian Stage, tropical to subtropical, neritic to upper bathyal taxa (Wilson, 1954). San Emigdio Region, Grapevine 7V2-minute quadrangle (USGS 13080, 13084; localities 0.5-2 mi up Salt Creek from its mouth; west side of creek, in sandstone immediately below a basalt. Specimens collected in 1912 by R.G. Davies from strata referred to the Temblor Formation by Nilsen and others (1973) and placed near the Saucesian-Zemorrian boundary. Vertipecten perrini from here is similar to the La Panza specimens (M4737) and is indicative of the lower "Vaqueros" Stage. Geologic age.— Middle Oligocene to late Oligocene. Biostratigraphic data.— Unnamed stage to lower "Vaqueros" Stage. It is found at many localities with "Macrochlamis" magnolia s.s., another lower "Vaqueros" Stage index fossil. Transitional forms between V. yneziana or V. alexclarki and V. perrini are from the unnamed megafaunal stage of Addicott (1972).» 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 + 1-155, figs. 1-18, pls. 1-38. [p. 84, 85]
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Vertipecten perrini
(Arnold, 1906); J. T. Smith, 1991, Cenozoic Giant Pectinids from California and the Tertiary Caribbean Province, plate 32, figure 2 (above); plate 37, figures 1, 5, 6 (below). |
«This large form, sometimes difficult to differentiate from Pecten bowersi Arnold (1906), is perhaps the most variable species of the Lyropectens. In some specimens the more convex valve is almost identical to that of P. bowersi. The characteristically flatter P. perrini has a possible Oligocene ? ancestral form which is found in the western Santa Ynez Mountains (in a zone stratigraphically intermediate between the lowest typical Vaqueros faunule and the highest Oligocene (?) zone), which was described by Arnold (1907a) as P. inezana [sic]. The two forms are almost, if not, identical. P. perrini is distinct from other similar species in its usual flatness of the right valve and irregular scaly ribbing.
Geologic range.— From Oligocene (?) to Vaqueros, Lower Miocene and Temblor, Middle Miocene. Distribution in Vaqueros.— San Joaquin Hills, Orange County; Santa Monica Mountains and Oak Ridge, Ventura County; western Santa Ynez Mountains, Santa Barbara County; San Emigdio Mountains, Kern County; southern Santa Lucia Mountains, San Luis Obispo County; Bryson region-Nacimiento River, Monterey County; La Panza, eastern San Luis Obispo County; Vaqueros Greek, San Antonio River, Monterey County; Corte Madera Creek, San Mateo County.» 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. 201]
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Pecten (Lyropecten) perrini Arnold; W. Loel & W. H. Corey, 1932, The Vaqueros formation, lower Miocene of California I. Paleontology, plate 23, figure 1; plate 24, figure 1.
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