Radulopecten scarburgensis (Young & Bird, 1822)
YOUNG, G. & J. BIRD. 1822. A geological survey of the Yorkshire coast: describing the strata and fossils occurring between the Humber and the Tees, from the German ocean to the plain of York. 336 p., pls. 1-17. Printed at the Office of George Clark. Whitby, 1822. [p. 234, pl. 9, fig. 10]
1822 Pecten scarburgensis Young & Bird, 1822
1833 Pecten subarmatus Münster in Goldfuss, 1833
1833 Pecten subcancellatus Münster in Goldfuss, 1833
1845 Pecten discrepans Brown, 1845
1859 Pecten bavoux Contejean, 1859
1862 Pecten laurae Étallon in Thurmann & Étallon, 1862
1915 Pecten catharinae Rollier, 1915
1936 Chlamys (Radulopecten) tipperi Cox, 1936
1952 Chlamys (Radulopecten) moondanensis Cox, 1952
1965 Chlamys (Radulopecten?) kinjeleensis Cox, 1965
1833 Pecten subarmatus Münster in Goldfuss, 1833
1833 Pecten subcancellatus Münster in Goldfuss, 1833
1845 Pecten discrepans Brown, 1845
1859 Pecten bavoux Contejean, 1859
1862 Pecten laurae Étallon in Thurmann & Étallon, 1862
1915 Pecten catharinae Rollier, 1915
1936 Chlamys (Radulopecten) tipperi Cox, 1936
1952 Chlamys (Radulopecten) moondanensis Cox, 1952
1965 Chlamys (Radulopecten?) kinjeleensis Cox, 1965
G. Young & J. Bird, 1822, plate 9.
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«Fig. 10 represents the inside of a handsome shell, of a larger size, and more oblong shape, from the hard sandstone at the foot of Scarborough castle. Some specimens are three inches long, but it is very difficult to get any entire. Both valves are convex, and, as in No. 12, are closely invested with transverse membranaceous striae, somewhat sharp and rough, crossing both the ribs and the intermediate grooves. There are nine ribs, which are broad and rather flat, but each has an elevated ridge running along the middle of it, surmounted here and there with oblong spines, or sharp scales, crossing the ridge. As this species does not appear to have been hitherto described, we may name it p. Scarburgensis.»
GEORGE YOUNG & JOHN BIRD, 1822
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«Remarks. R. fibrosus and R. scarburgensis are two very close species. The main differences between them are asfollows: The specimens attributed to R. fibrosus have the typical ornamentation of this species. The right valve has 7 radial ribs flatter and wider than sulci. The left valve has 10 radial ribs more prominent and narrower than sulci. The specimen assigned to R. scarburgensis presents faint radial ribs on the umbonal region of the right valve. Moreover, the surface of scarburgensis is covered with 10 radial ribs on the left valve, and 11 on the right valve. The strongest convexity is present in the left valve in R. fibrosus and in the right valve in R. scarburgenis. JOHNSON (1984) discusses the two species in detail.»
DELVENE, G. 2007. Middle and Upper Jurassic bivalves from the Geomining Museum collections (IGME, Geological Survey of Spain). Beringeria, 37: 11-31, pls. 1-5.
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Radulopecten scarburgensis (Young & Bird, 1822); G. Delvene, 2007, Middle and Upper Jurassic bivalves from the Geomining Museum collections, plate 4, figures 2a, 2b.
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«2. AMENDED DIAGNOSIS
Distinguished from R. fibrosus by the presence of radial striae, from R. sigmaringensis by the presence of comarginal lamellae rather than spines, from R. inequicostatus by the equality of the initial plicae and from all other species of Radulopecten by the lack of a non-plicate zone.
3. AMENDED DESCRIPTION
Essentially similar to R. fibrosus, differing by the larger maximum height (92 mm, M NP; possibly 170 mm, see Section 4), more variable umbonal angle (text fig. 195), somewhat greater convexity, and tendency for the right valve to be the more convex, by the more equal-sized auricles and tendency for all the auricles to meet the hinge-line at an acute angle and of the anterior auricle of the right valve to meet the disc at an obtuse angle, by the generally smaller byssal notch and by the ornament of the disc (other metric proportions plotted in text figs. 194, 196-8).
Left valve bearing between 8 and 11 original plicae (text fig. 193), width and height variable both between individuals and in ontogeny. Forms with narrow plicae late in ontogeny adding to number by intercalation (e. g. PI. 10, Fig. 27). Plicae bearing variably spaced co marginal lamellae; spacing strongly correlated with plical height (e. g. PI. 10, Fig. 23). Sulci with or without comarginal lamellae; presence strongly correlated with relatively close spacing of plical lamellae (compare PI. 10, Figs. 28 and 29). Right valve usually bearing one more plica than left. Closely spaced comarginal striae on both plicae and sulci, sometimes raised into lamellae on the most anterior and posterior of the plicae (PI. 10, Fig. 26) and on the ventral part of the medial plicae in large specimens. Both valves bearing numerous fine radial striae in the umbonal region. Shell thickness usually moderate but becoming quite high in large specimens. 4. DISCUSSION
Although the type material of 'pecten' Scarburgensis YOUNG and BIRD appears to have been lost, mention in the original description (see Section I) of 'nine ribs' can leave little doubt that it was representative of the species described in Section 3 rather than the species with which it was compared ('P.' fibrosus J. SOWERBY). Moreover, the type locality, at the foot of Scarborough Castle, is at a horizon (Hackness Rock) at which the former species is common (see Section 7) but at which the latter appears to be absent. Accordingly the species described in Section 3 is known hereinafter as Radulopecten scarburgensis. DUFF (1978) has designated as neotype a left valve (SM J12398) whose plicae are initially high and fairly wide but become relatively low and somewhat narrow later in ontogeny, and whose plical lamellae are fairly widely spaced early in ontogeny and closely spaced later, but continuous across the sulci at all stages of growth.
PHILLIPS (1829) and D'ORBIGNY (1850) misinterpreted J. SOWERBY's (1816) hypodigm for 'P.' fibrosus and applied this name to specimens of R. scarburgensis. Subsequently, numerous authors have similarly misapplied J. SOWERBY's specific name (see R. fibrosus for a fuller discussion). BROWN (1845) realised PHILLIPS' mistake and erected 'P.' discrepans for the latter's figured specimen. D'ORBIGNY's species 'P.' subfibrosus, erected for forms which are in fact identical to J. SOWERBY's species, was itself misapplied by de LORIOL (1901, ?1897, ?1900, ?1904) to specimens of R. scarburgensis.» JOHNSON, A. L. A. 1984. The palaeobiology of the bivalve families Pectinidae and Propeamussiidae in the Jurassic of Europe. Zitteliana, 11: 1-235, pls. 1-11. [p. 210, 211]
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Radulopecten scarburgensis (Young and Bird 1822); A. L. A. Johnson, 1984, The palaeobiology of the bivalve families Pectinidae and Propeamussiidae in the Jurassic of Europe, plate 10, figures 23, 25-29, ? figure 19; ? plate 11, figures 1, 3.
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«Remarks. C. (R.) scarburgensis (Young & Bird, 1822) was overlooked for over a century before Arkell (1935, p. xiii) recognized it as a valid species. This was at least in part due to the similarity between this species and the close relative C. (R.) fibrosa (J. Sowerby), which ranges from the Kellaways Rock to the Upper Oxfordian. There are, however, marked differences between the two with C. (R.) scarburgensis having fewer, more divergent ribs, of equal prominence in each valve, these ribs being narrower than in C. (R.) fibrosa; it also lacks the radial striae which occur in the sulci of C. (R.) fibrosa. The neotype is the largest specimen known (L 41.5 mm), although Young & Bird (1822, p. 234) in their original diagnosis stated that "some specimens are three inches long", and it is from this measurement that the maximum size (L 76 mm) is inferred.
Phillips (1829, pl. 6, fig. 3) figured a topotype of C. (R.) scarburgensis, which he identified as P. fibrosus J. Sowerby, but there can be little doubt from his plate that his specimen, now lost, did not belong to Sowerby's species. Brown (1845, p. 157) realized that Phillips had misidentified his specimen, and renamed it Pecten discrepans nom. nov., overlooking Young & Bird's prior name. Several continental authors (see synonymy) followed Phillips in misidentifying Sowerby's species, and referred specimens of C. (R.) scarburgensis to C. (R.) fibrosa. Stoll (1934, p. 21, pl. 2, figs. 16-20) described Pecten (Aequipecten) fibrosus J. Sowerby, together with two new varieties of the species, from erratic boulders of Upper Jurassic age in north-west Germany. Study of large collections of C. (R.) fibrosa and C. (R.) scarburgensis shows the variability in form of the two species, and from this it is clear that all of Stall's figures, except her plate 2, figure 16, belong to C. (R.) fibrosa. The latter specimen agrees well in size and ribbing style with topotypes of C. (R.) scarburgensis. Dechaseaux (1936, p. 47) also confused the two species, placing all her specimens in Aequipecten fibrosus, but it is clear from her plates (pl. 6, figs. 15-20; pl. 7, figs. 1-3) that more than two species are represented: her pl. 6, figs. 17, 17a, 20 are clearly different from both C. (R.) fibrosa and C. (R.) scarburgensis, as are her pl. 7, figs. 2, 3. Much work on her specimens is needed before they can be correctly interpreted, but it seems likely that her pl. 6, figs. 15, 18, 18a, 19 and pl. 7, fig. 1 may represent C. (R.) scarburgensis. C. (R.) drewtonensis Neale differs in that the left valve is slightly more inflated than the right, and in the possession of a very prominent anterior auricle on the right valve. The anterior auricle is ornamented by 9 fine radial striae in its proximal 6-5 mm. Range and occurrence. In Britain, the Upper Cornbrash of Scarborough, the Kellaways Rock of Kellaways, Wiltshire, the Hackness Rock of Scarborough, and the "Oxford Clay of Brill, Buckinghamshire" (GSM 42985). One fragmentary specimen from the endodatum Subzone o f Stewartby; more abundant in the Middle to Upper Oxford Clay of Oxfordshire and at Woodham (many specimens in OUM). Callovian of Germany (Stall 1934), France (Raspail 1901; Cossmann 1924) and Russia (Lahusen 1883); Oxfordian of France (Dechaseaux 1936).» DUFF, K. L. 1978. Bivalvia from the English Lower Oxford Clay (Middle Jurassic). Palaeontographical Society. Monograph 553: 1-137, pls. 1-13. [p. 71, 72]
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Chlamys (Radulopecten) scarburgensis (Young & Bird, 1822); K. L. Duff, 1978, Bivalvia from the English Lower Oxford Clay (Middle Jurassic), plate 5, figures 19, 20, 23, 24, 26, 27; plate 6, figures 1, 5, 6.
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