Camptonectes subulatus (Münster in Goldfuss, 1835)
GOLDFUSS, A. 1833-1840. Petrefacta Germaniae tam ea, quae in museo universitatis regiae Borussicae Fridericiae Wilhelmiae Rhenanae servantur quam alia quae cunque in museis hoeninghusiano, muensteriano aliisque extant, iconibus et descriptionibus illustrata. Zweiter Theil, 312 p., pls. 1-199. Arnz & Co., Düsseldorf. [p. 73, pl. 98, figs. 12 a-c]
1835 Pecten substriatus Roemer, 1835
1835 Pecten subulatus Münster in Goldfuss, 1835
1835 Pecten calvus Goldfuss, 1835
1850 Pecten castor Orbigny, 1850
1858 Pecten strionatis Quenstedt, 1856
1858 Pecten punctatissimus Quenstedt, 1856
1865 Pecten jamoignensis Terquem & Piette, 1865
1870 Pecten lohbergensis Emerson, 1870
1878 Pecten bellampensis Gemmellaro and Di Blasi in Gemmellaro, 1878
1881 Pecten tullbergi Lundgren, 1881
1884 Pecten punctatus Simpson, 1884
1895 Pecten rinki Lundgren, 1895
1917 Pecten tingensis Tilmann, 1917
1923 Pecten dehmensis Ernst, 1923
1923 Pecten (Pleuronectites) sublaevigatus Ernst, 1923
1956 Camptonectes mundus Melville, 1956
1972 Camptonectes (Camptonectes) fromageti Hayami, 1972
1835 Pecten subulatus Münster in Goldfuss, 1835
1835 Pecten calvus Goldfuss, 1835
1850 Pecten castor Orbigny, 1850
1858 Pecten strionatis Quenstedt, 1856
1858 Pecten punctatissimus Quenstedt, 1856
1865 Pecten jamoignensis Terquem & Piette, 1865
1870 Pecten lohbergensis Emerson, 1870
1878 Pecten bellampensis Gemmellaro and Di Blasi in Gemmellaro, 1878
1881 Pecten tullbergi Lundgren, 1881
1884 Pecten punctatus Simpson, 1884
1895 Pecten rinki Lundgren, 1895
1917 Pecten tingensis Tilmann, 1917
1923 Pecten dehmensis Ernst, 1923
1923 Pecten (Pleuronectites) sublaevigatus Ernst, 1923
1956 Camptonectes mundus Melville, 1956
1972 Camptonectes (Camptonectes) fromageti Hayami, 1972
A. Goldfuss, 1833-1840, plate 98.
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«Fig. 12. a. Valva dextra et Die rechte und
b. sinistra. inke Schale c. Particula aucta. Ein vergrössertes Stückchen. Pecten testa oblique ovali aequivalvi inaequilaterali convexo-plana laevi, striis radiantibus et concentricis vix conspieuis, auricula antica elongata basique sinuata. — E montibus Bavaricis et Würtembergicis. M. M.
Gleichklappig, schief, oval-kreisrund, flach-convex, glatt und glänzend. Durch Vergrösserung erkennt man sehr zarte, gedrängte concentrische Streifen und einige ausstrahlende Linien. Die Ohren sind in etwas abweichender schiefer Richtung abgeschnitten, die hinteren sehr kurz, die vorderen aber weit über den Rand hinaus verlängert. — Findet sich im Liaskalk bei Altdorf, Amberg , Elwangen und Wasser - Alfingen.»
GEORG MÜNSTER, 1835
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«2. AMENDED DIAGNOSIS
Distinguished from C. (C.) auritus and C. (C.) laminatus by the restriction of surficial ornament to the anterior and posterior margins. Distinguished from C. (C.) virdunensis by the more orbicular disc.
3. AMENDED DESCRIPTION
Disc sub-orbicular, slightly higher than long at all stages in ontogeny (text fig. 89); maximum height 52.5 mm (GPIT). Umbonal angle very variable (text fig. 90) but increasing during ontogeny to produce concave dorsal margins. Disc flanks very low.
Equilateral; inequivalve, low convexity, left valve slightly more convex than right. Intersinal distance variable, greater in left valve than right (text figs. 91,92) but increasing isometrically in both. Depth of byssal notch very variable (text fig. 93) but usually increasing isometrically. Auricles well demarcated from disc, variable in size, anterior larger than posterior. Posterior auricles meeting hinge line at an obtuse angle and disc at an acute angle. Anterior auricles meeting hinge line at about 90°; that of left valve meeting disc at an acute angle, that of right valve meeting disc at 90° or more. All auricles ornamented with fine comarginal striae and where well preserved, fine divaricate striae. Height of anterior auricle and length of posterior hinge increasing with approximate isometry (text figs. 94, 95). Length of anterior hinge possibly increasing at a decreasing rate (text fig. 96). Centre of disc exterior smooth in both valves. In well preserved specimens anterior and posterior margins, particularly in the dorsal region, bearing fine divaricate striae (PI. 4, Fig. 3), rendered 'punctate' by the intersection of comarginal striae. Inner shell layers formed into radial striae of low amplitude (PI. 4, Fig. 8). Shell very thin. Outer layer including at least one sub-layer of divaricate fibres. 4. DISCUSSION
The taxonomy of the weakly ornamented L. Jurassic Pectinidae has been a subject of considerable confusion. Distinction at the generic level is dealt with on pp. 35, 107. The proliferation of names at the specific level has resulted largely from a failure to appreciate the wide but continuous range of variation in metric proportions of the species described in Section 3 and the ränge of sculptural patterns in the latter resulting from abrasion and dissolution of the thin shell. Four main sculptural patterns (analogous fo those observed in Propeamussium (P.) pumilum by Holder (1978)) can be recognised in the passage from complete shell preservation to internal mould.
a) Perfect preservation produces shells eonforming to the description in Section 3.
b) Loss of the very thin shell layer bearing 'Camptonectes-ornament' on the lateral disc margins and auricles, leaves a smooth but relativelv thick shell bearing traces only of comarginal striae (PI. 4, Figs. 4, 7). c) Loss of a further shell layer results in the exposure of radial striae which form a reticulate pattern with the comarginal striae (Pl. 4, Fig. 5; postero-ventral of centre), this standing out as rows of comarginal 'punctae' (cf. a) in suitably fine sediment. d) Loss of the remainder of the outer layer leaves only the radial striae of the inner shell layers which persist to the internal shell surface and thus appear on moulds (PI. 4, Fig. 8). Paired valves often exhibit different sculpture, with the right valve usually representing a more ad vanced state of abrasion, presumably as the result of more frequent contact with the substratum during life.
BM L40676 (PI. 4, Fig. 5) exhibits, in different parts of the shell, each of the first three preservation states referred to above, thus convincingly demonstrating that they do not reflect genetic differences. That forms corresponding to preservation state d) are conspecific is made clear by the fact that their metric proportions (specimens marked with a glyph in text figs. 89-96) are inseparable from more perfectly preserved specimens. However, the development of fine radial striae is not restricted to the species under discussion but is also seen in, for instance, small or abraded examples of the 'fine' phenotype of Chlamys (Ch.) textoria. Thus, where original material and figures are poor or lacking and descriptions inadequate, there remains considerable taxonomic uncertainty (see below).» 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. 108-110]
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Camptonectes (Camptonectes) subulatus (Münster 1836); A. L. A. Johnson, 1984, The palaeobiology of the bivalve families Pectinidae and Propeamussiidae in the Jurassic of Europe, plate 4, figures 3-5, 7, 8; ? figures 6, 9.
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