Neithea atava (F. A. Roemer, 1839)
ROEMER, F. A. 1839. Die Versteinerungen des Norddeutschen Oolithen-Gebirges. Ein Nachtrag. iv, 59 p., pls. 17-20. Im Verlage der Hahn'schen Hofbuchhandlung. Hannover, 1839 [p. 29, pl. 18, fig. 21]
1839 Pecten atavus Roemer, 1839
1847 Janira neocomiensis Orbigny, 1847
1883 Pecten (Neithea) ornithopus Keeping, 1883
1905 Vola neumanni Dacqué, 1905
1910 Vola lindiensis Krenkel, 1910
1953 Neithea atava saxatilis Mongin & Trouve, 1953
1965 Neithea (Neithea) kanmerai Hayami, 1965
1847 Janira neocomiensis Orbigny, 1847
1883 Pecten (Neithea) ornithopus Keeping, 1883
1905 Vola neumanni Dacqué, 1905
1910 Vola lindiensis Krenkel, 1910
1953 Neithea atava saxatilis Mongin & Trouve, 1953
1965 Neithea (Neithea) kanmerai Hayami, 1965
F. A. Roemer, 1839, plate 18.
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«P. (Jacobaeus) testa ovato-acuta concentrice subtilissime lineata inferne sexangulari, valva sinistra plana margine incrassata interne dense subsulcato, dextra convexo-gibba costis senis elatis rotundatis, interstitiis planis latis quadrisulcatis.
Es gehört diese Art zur Familie der Jacobäen, und ist die früheste, bislang bekannte Form derselben. Das Gehäuse ist spitz eirund, unten sechskantig. Die linke Schale ist platt, hat innen einen sehr verdickten Rand, zahlreiche Längsstreifen und aussen vier stärkere Rippen; die rechte Schale ist sehr stark gewölbt und trägt sechs dicke, runde Längsrippen. Die breiten Zwischenräume sind platt, zeigen 3 bis 4 schwache Längsfurchen und sehr feine, regelmässige, aufwärts gebogene, dicht stellende Anwachsungslinien.
Wird selbst doppelt so gross, als das abgebildete Exemplar, und findet sich im Hilse bei SchandeIahe und Schöppenstedt nicht selten.» FRIEDERICH ADOLPH ROEMER, 1839
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«Material: One flat and two convex valves, from Sa Oche (Lanaitto), Lower Hauterivian (n. 763, 774) and from the Orudè area (Dorgali), Lower-Middle Hauterivian (n. 631).
Dimensions (mm): n. 763: H = 30; L = (20).
Discussion: The Sardinian specimens show the typical rib structure of N. atava. None of the collected specimens reach the dimensions recorded from other Tethyan regions [Japan, Georgia (USSR), Ethiopia, Tanzania].
Distribution: Berriasian?, Valanginian - Aptian, southern part of the north Temperate Realm and Tethys: France (Paris Basin and SE), Germany, Switzerland, Sardinia, Spain, Bulgaria, USSR (Crimea, Caucasus, Central Asia), Japan, Ethiopia, Tanzania, Algeria, Mexico and Trinidad (Text-fig. 14).»
DHONDT, A. V. & I. DIENI. 1988. Early Cretaceous bivalves of eastern Sardinia. Memorie di Scienze Geologiche, 40: 1-97, pls. 1-13, text-figs. 1-25. [p. 32, 33]
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Neithea (Neithea) atava (Roemer); A. V. Dhondt & I. Dieni, 1988, Early Cretaceous bivalves of eastern Sardinia, plate 6, figures 10-12.
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«Remarks.— In Japan this giant species has been called Neithea (Neithea) kanmerai, since one of us (HAYAMI, 1965) proposed it as a new specific name. DHONDT (1973) examined many hitherto described specimens of Neithea from Europe and clarified the diagnostic characters of N. atava which had been somewhat controversial among authors. At the same time she properly pointed out that N. kanmerai from Japan is synonymous with N. atava of original sense. On the other hand, several well preserved specimens were recently collected from the Haidateyama Formation of central Kyushu and the Arida Formation of Kii Peninsula.
The shell material is completely eroded away except for an incomplete conjoined specimen (UMUT MM5706), but the surface ornamentation of two valves are well recognizable in other external moulds. The hinge structure is exhibited in the right internal mould (NSM MM7348) and the auricles are completely impressed on the left external mould (UMUT MM5703). The characteristic shape of primary ribs, which are tripartite in the right valve and bipartite in the left, is commonly seen, while the secondary ribs of two valves seem to be considerably variable in prominence. In 1965, one of us proposed Neithea kanmerai mainly on the basis of four deformed right internal moulds and one incomplete left external moulds from the Aptian Hinagu Formation of central Kyushu. Because the original description was based on such incomplete material, the external features of right valve were not precisely known, and the mode of radial ornament, especially the relationship of surface relief between two valves, was erroneously interpreted. As the result of reexamination on the Hinagu specimens, the primary ribs of left valve must be also six in number (instead of five) and distinctly bipartite. Tripartition of primary ribs in right valve is hardly ascertained from the impression of radials on the internal moulds, but it is also indistinct in the newly obtained internal moulds. Anyhow, no essential difference can be found between the type specimens of N. kanmerai and the present material. On the other hand, as pointed out by DHONDT (1973), the Hinagu specimens as well as the present ones are quite similar to the European specimens of Neithea (Neithea) atava (ROEMER, 1839) of proper sense in every diagnostic character. In addition to the occurrence in western Europe and north Africa, several firmly identical specimens were recorded from the Barremian or Aptian of Trinidad (COX, 1954), Lower Cretaceous of southeast Mexico (ALENCASTER, 1956) and Hauterivian-Aptian of Crimea and Caucasus (DRUSCHIZA and KUDRJAVTSEVA, 1960). In every area N. (N.) atava is distinguishable from other species by the enormously large size and characteristic radial ribbing, and its geographic variation in morphology, if present, seems to be rather slight.» HAYAMI, I. & M. NODA. 1977. Notes on the morphology of Neithea (Cretaceous pectinids) with taxonomic revision of japanese species. Transactions and Proceedings of the Palaeontological Society of Japan [N. S.], 105: 27-54, pls. 5, 6. [p. 43, 44]
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Neithea (Neithea) atava (Roemer); I. Hayami & M. Noda, 1977, Notes on the morphology of Neithea (Cretaceous pectinids) with taxonomic revision of japanese species, plate 5, figures 4, 5; plate 6, figures 1, 2.
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«Synonymy.— Janira neocomiensis D'ORBIGNY is not different from N. atava (ROEMER); the arguments used by D'ORBIGNY to differentiate both «species» are easily explained by the difference in size and state of preservation. The fact quoted by him: «... se trouve généralement avec le J. atava» is also an indication that it is one and the same species. Janira neocomiensis are young individuals of N. atava.
Vola neumanni DACQUÉ, from the Lower Cretaceous of Ethiopia, is, as DACQUÉ himself already supposed, a very large specimen of N. atava. Similar specimens are found in the Alpine Neocomian. The relative flatness and irregular rib distribution are due to the size of the specimen. Vola lindiensis KRENKEL from the Tendaguru-Schichten as figured by KRENKEL is not a convincing Neithea atava. In the British Museum (Nat. Hist.) a series of specimens is kept from the same locality which undoubtedly belong to the same species. Dr. N. J. MORRIS attracted my attention to the fact that those specimens do not specifically differ from N. atava. The largest specimens are very much larger than the sizes mentioned by ROEMER and D'ORBIGNY but as no other differences can be found there appears to be no reason to keep them separated from N. atava. Neithea (Neithea) kanmerai HAYAMI: by following H. WOODS interpretation of N. atava, HAYAMI found himself compelled to create a new species for specimens which are obviously large N. atava; he has been misled by D'ORBIGNY's description of N. atava: the figure is supposed to be in «grandeur naturelle», where in fact its scale is 3/2; this explains the relatively narrow beak on the figure and on this HAYAMI bases the differentiation. HAYAMI's differences in ribs structure are due to the fact that he only possesses «Steinkernen». Differentiation.— Compared with other Neithea-species Neithea atava has always been well isolated. Only H. WOODS misinterpreted the species, which is certainly very rare for him. As N. atava he described large specimens of N. notabilis (MUENSTER in GOLDFUSS). When well preserved both species are easily differentiated because N. atava is a Neithea s. s. and has equal or subequal auricles whereas N. notabilis is a Neithella and has very unequal auricles.
Very worn individuals of N. syriaca (CONRAD) or N. quinquecostata (SOWERBY) could be taken for N. atava because of the general shape; this only seldom happens because there is a stratigraphical discrepancy. From all other Neithea-species N. atava can be differentiated by the absence of proper intercalary ribs. From Neithella-species it differs in having subequal auricles.» DHONDT, A. V. 1973. Systematic revision of the subfamily Neitheinae (Pectinidae, Bivavia, Mollusca) of the European Cretaceus. Mémoires du Institute Royal des Sciences Naturelles de Belgique, 176: 1-101, pls. 1-5. [p. 43]
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Neithea (Neithea) atava (F. A. Roemer, 1839); A. V. Dhondt, 1973, Systematic revision of the subfamily Neitheinae of the European Cretaceus, plate 1, figures 1a, 1b.
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