Camptonectes auritus (Schlotheim, 1813)
SCHLOTHEIM, E. F. VON. 1813. Beiträge zur Naturgeschichte der Versteinerungen in geognostischen Hinsicht. Leonard’s Taschenbuch für die gesammte Mineralogie, 7: 3-134. [p. 103]
1813 Chamites auritus Schlotheim, 1813
1818 Pecten lens J. Sowerby, 1818
1818 Pecten arcuata J. Sowerby, 1818
1822 Pecten maltonenesis Young & Bird, 1822
1833 Pecten comatus Münster in Goldfuss, 1833
1839 Pecten decheni Roemer, 1839
1839 Pecten buchii Roemer, 1839
1850 Pecten lusitanicus Sharpe, 1850
1850 Pecten midas Orbigny, 1850
1850 Pecten saturnus Orbigny, 1850
1862 Pecten parandieri Étallon in Thurmann & Étallon, 1862
1862 Pecten delessei Étallon in Thurmann & Étallon, 1862
1866 Pecten validus Lindstrom, 1866
1867 Pecten aratus Waagen, 1867
1871 Pecten nitescens Phillips, 1871
1874 Pecten subvitreus Gemmellaro & Di Blasi, 1874
1880 Pecten clipeatus Witchell, 1880
1882 Pecten gracilis Alth, 1882
1883 Pecten triformis Whidborne, 1883
1886 Pecten neumayri Gregorio, 1886
1886 Pecten anughus Gregorio, 1886
1886 Pecten etalloni De Loriol in De Loriol & Pellat, 1886
1886 Pecten morini De Loriol in De Loriol & Pellat, 1886
1893 Pecten letteroni De Loriol in De Loriol & Lambert, 1893
1893 Pecten nais De Loriol, 1893
1916 Camptonectes aalensis Paris & Richardson, 1916
1926 Camptonectes giganteus Arkell, 1926
1926 Camptonectes psilonoti Staeche, 1926
1930 Camptonectes sandsfootensis Arkell, 1930
1936 Camptonectes mairei Dechaseaux, 1936
1951 Chlamys interpunctata Troedsson, 1951
1974 Camptonectes greenhoughi Skwarko, 1974
1818 Pecten lens J. Sowerby, 1818
1818 Pecten arcuata J. Sowerby, 1818
1822 Pecten maltonenesis Young & Bird, 1822
1833 Pecten comatus Münster in Goldfuss, 1833
1839 Pecten decheni Roemer, 1839
1839 Pecten buchii Roemer, 1839
1850 Pecten lusitanicus Sharpe, 1850
1850 Pecten midas Orbigny, 1850
1850 Pecten saturnus Orbigny, 1850
1862 Pecten parandieri Étallon in Thurmann & Étallon, 1862
1862 Pecten delessei Étallon in Thurmann & Étallon, 1862
1866 Pecten validus Lindstrom, 1866
1867 Pecten aratus Waagen, 1867
1871 Pecten nitescens Phillips, 1871
1874 Pecten subvitreus Gemmellaro & Di Blasi, 1874
1880 Pecten clipeatus Witchell, 1880
1882 Pecten gracilis Alth, 1882
1883 Pecten triformis Whidborne, 1883
1886 Pecten neumayri Gregorio, 1886
1886 Pecten anughus Gregorio, 1886
1886 Pecten etalloni De Loriol in De Loriol & Pellat, 1886
1886 Pecten morini De Loriol in De Loriol & Pellat, 1886
1893 Pecten letteroni De Loriol in De Loriol & Lambert, 1893
1893 Pecten nais De Loriol, 1893
1916 Camptonectes aalensis Paris & Richardson, 1916
1926 Camptonectes giganteus Arkell, 1926
1926 Camptonectes psilonoti Staeche, 1926
1930 Camptonectes sandsfootensis Arkell, 1930
1936 Camptonectes mairei Dechaseaux, 1936
1951 Chlamys interpunctata Troedsson, 1951
1974 Camptonectes greenhoughi Skwarko, 1974
«2. DIAGNOSIS
Distinguished from C. (C.) laminatus by the generally finer ornament, from C. (C.) subulatus by the presence of ornament on all parts of the disc and from C. (C.) virdunensis by the more orbicular disc.
3. DESCRIPTION
Disc sub-ovate, higher than long early in ontogeny, growing allometrically to become sub-orbicular and finally subovate, longer than high (text fig. 98), near the maximum height of 150 mm (OUM J2361). Umbonal angle very variable (text fig. 99), increasing at a decreasing rate during ontogeny. Dorsal margins concave, disc flanks low.
Inequilateral, anterior greater than posterior half length; inequivalve, low convexity, lett valve more convex than right. Intersinal distance variable, greater in left valve than right, apparently increasing with respect to length at a slower rate in U. Jurassic cf. M. Jurassic representatives (text figs. 100, 101). Byssal notch depth variable, moderate to large (text fig. 102), increasing isometrically. Auricles well demarcated from disc, variable in size, anterior larger than posterior. Anterior auricle of right valve meeting hinge line and disc at about 90°. Other auricles meeting hinge line at an obtuse angle and disc at an acute angle. All auricles ornamented with fine comarginal striae. Posterior auricle of right valve also bearing divaricate striae. Height of anterior auricle and length of anterior hinge variable, increasing with respect to length at a decreasing rate in all populations (text figs. 103, 104). Length of posterior hinge variable, increasing with respect to length at a slower rate in U. cf. M. Jurassic representatives (text fig. 105). Disc exterior ornamented with a variable number of fine divaricate striae (e. g. PI. 3, Figs. 32, 33) increasing in number by intercalation and rendered 'punctate' by the intersection of growth hnes. Shell thickness low to moderate. 4. DISCUSSION
The systematics of the essentially finely-ornamented and orbicular species of C. (Camptonectes) described above has been the subject of much, often heated, debate. Failure to appreciate the range of static, ontogenetic and ecophenotypic variation in both ornamentation and metric proportions, allied to the typological approach of early authors has led to the designation of a plethora of specific names. The indiscriminate lumping of many of these names by early revisionists who failed to examine type material has led to a secondary source of confusion (see Arkell, 1930a for a review). However, later revisionists have also been lamentably at fault in their failure to unite stratigraphically separated but morphologically indistinguishable forms. The result is almost unparalleled nomenclatural chaos.»
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. 116, 117]
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Camptonectes (Camptonectes) auritus (Schlotheim 1813); A. L. A. Johnson, 1984, The palaeobiology of the bivalve families Pectinidae and Propeamussiidae in the Jurassic of Europe, plate 3, figures 25-40.
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«Remarks. The provenance of J. Sowerby's two syntypes of Pecten lens, said to be "the forest marble near Oxford", has been shown by Arkell (1930, p. 95) actually to be the Corallian Beds (Berkshire Oolite "Series") of Headington, Oxford. Arkell has also shown that several species of Camptonectes may be distinguished in the Middle and Upper Jurassic of Europe, and that there is no justification for uniting all Middle and Upper Jurassic species in Camptonectes lens, as was done by Staesche (1926). Arkell also noted that much of the confusion over the species of Camptonectes was caused by using Sowerby's names without consulting the type specimens. The common Callovian to Kimmeridgian species C. auritus may easily be distinguished from the Bajocian to Bathonian C. laminatus (J. Sowerby); the latter is narrower and more subovate (L x 85%, umbonal angle x 90°), has a tendency for the ornament of the left valve to coarsen in larger specimens (the divaricate threads almost becoming riblets), and has different ornament patterns on the auricles. In C. laminatus, the left anterior auricle and the right posterior auricle both have about 10 conspicuous raised vertical lamellae.
Several entries omitted by Arkell have been placed in the synonymy here. Pecten maltonensis Young & Bird is clearly conspecific, their figure showing a well-preserved right valve, and it is probable that their figure of P. lens (1828, pl. 9, fig. 18) represents a poorly-preserved left valve, although there seems to be a lack of divaricate ornament. Couffon's (1919) figure of P. lens shows a poorly-preserved steinkern of similar shape to Camptonectes, but lacking all external ornament. Arkell (1930, p. 96) recorded C. auritus from the Forest Marble of Chippenham (GSM 49043); the specimen is rather narrower than is usual for that species and it is better placed in C. laminatus. Range and occurrence. Upper Cornbrash, Kellaways Rock, Hackness Rock, Corallian Beds and Kimmeridge Clay of Britain; rare in Inverbrora Shale Member (Callovian) of Brora, Sutherland. Lower Oxford Clay of the English Midlands, in the enodatum Subzone at Stewartby, and medea Subzone at Bletchley. Widespread in Callovian to Kimmeridgian of Europe (Arkell 1930, p. 94).» DUFF, K. L. 1978. Bivalvia from the English Lower Oxford Clay (Middle Jurassic). Palaeontographical Society. Monograph 553: 1-137, pls. 1-13. [p. 67, 68]
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Camptonectes (Camptonectes) auritus (Schlotheim, 1813); K. L. Duff, 1978, Bivalvia from the English Lower Oxford Clay (Middle Jurassic), plate 5, figures 22, 25.
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