Kolymonectes Milova & Polubotko in Bychkov et al., 1976
BYCHKOV, Y. M., A. S. DAGYS, A. F. EFIMOVA & I. V. POLUBOTKO. 1976. Atlas of the Triassic Fauna and Flora of Northeastern USSR. Ministry of Geology of RSFSR, “NEDRA”. Moscow. 267 p., pls. 1-72. (in Russian). [p. 66]
«Происхождение названия: Kolymo — от р. Колымы; песtes (лат.) — пловец.
Типовой вид. Aequipecten (?) anjuensis Мilоvа (Милова, 1969, стр. 182, табл. 1, фиг. 4). Нижний лейас. Бассейн р. Большого Анюя, р. Нижний Вургувеем. Диагноз. Раковина тонкостенная, небольшого или среднего размера, почти округлая со слабовыпуклыми створками. Поверхность левой створки всегда покрыта радиальными ребрами нескольких порядков, поверхность правой гладкая, с линиями роста или со слабо заметными следами радиальной скульптуры вдоль краев. Ушки почти равновеликие, но переднее несколько больше заднего. Биссусный вырез отсутствует или едва намечается под передним ушком правой створки. Обе створки снабжены внутренними боковыми валиками и вздутиями; задние боковые вздутия всегда немного шире и длиннее передних. Сравнение. По размерам ушек и отсутствию под передним ушком правой створки биссусного выреза раковины описываемого рода имеют сходство с Aequipecten Fischer. Однако скульптура правой и левой створок у них резко различна, что не свойственно представителям Aequipecten. От близкого рода Entolium новый род отличается хорошо развитой радиальной ребристостью на левой створке и отсутствием ушных внутренних валиков. Разнородность скульптуры на створках, почти полное ее отсутствие на правой створке, характер ушек и выпуклости раковины близки к этим признакам у рода Propeamussium de Gгеgогio, от которого новый род отличается отсутствием внутренних ребер. Видовой состав: Kolymonectes (?) koniensis (Tuchk.), K. anjuensis (Milova) , K. staeschei Polub.) , K. terekhovi (Polub.), K. (?) perrarus (Zakh.). Из них первый вид распространен в верхненорийско-рэтских отложениях Северо-Востока СССР, остальные являются юрскими. Распространение. Верхненорийско-рэтскне и юрские отложения Северо-Востока СССР и Севера Сибири.» LYDIA VASILEVNA MILOVA & INGA VLADIMIROVNA POLUBOTKO, 1976
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Kolymonectes anjuensis (Milova), 1969; L. V. Milova, 1976, Triassic-Jurassic stratigraphy and Bivalvia of northern Priokhotye, plate 11, figures 1-9.
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Kolymonectes carlottensis (Whiteaves 1884); M. Aberhan, 1998, Early Jurassic Bivalvia of western Canada. Part I. Subclasses Palaeotaxodonta, Pteriomorphia and Isofilibranchia, plate 11, figures 2, 4, 6, 9-11, 15.
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«Type species. Aequipecten (?) anjuensis Milova 1969.
Remarks. Recently, DAMBORENEA (1998) proposed that two stocks of Propeamussiidae were present in Mesozoic times. The first stock is characterized by genera with internal ribs such as Parvamussium. In a second stock taxa are grouped, which lack internal ribs, but on the basis of shell microstructure and the absence of a ctenolium can be referred to the Propeamussiidae. DAMBORENEA (1998) included Kolymonectes in the second stock and her view is followed here.
Kolymonectes is reported from Upper Triassic through Middle Jurassic strata of several regions of the circum-Pacific. In the Russian North-East, Lower Jurassic representatives of the genus appear to be of biostratigraphic importance (e.g. POLUBOTKO & REPIN 1988). Furthermore, Kolymonectes has been recorded from north-western Canada (POULTON 1991), western Argentina (e.g. DAMBORENEA 1993b), and also a specimen from New Zealand has been doubtfully included (DAMBORENEA & MANCEÑIDO 1992).» ABERHAN, M. 1998. Early Jurassic Bivalvia of western Canada. Part I. Subclasses Palaeotaxodonta, Pteriomorphia and Isofilibranchia. Beringeria, 21: 57-150, text-figs. 1-14, pls. 1-19. [p. 102, 104]
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S. E. Damborenea, 1993, Early Jurassic South American pectinaceans and circum-Pacific palaeobiogeography, figures 1, 2.
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«Kolymonectes Milova and Polubotko (in Bychkov et al., 1976)
This genus has hitherto been cited as a typical element of boreal faunas, restricted to the Late Triassic-Middle Jurassic (mainly Sinemurian-Pliensbachian, see Figs. 1 and 2) of northeast and far east Russia (Polubotko, 1968b; Milova, 1976; Bychkov et al. 1976; Fig. 3e) and northwest Canada (Poulton, 1991). It has been used by some authors to define the outline of the arctic subprovince of the Boreal province. Pecten coloradoensis Weaver (1931) from western Argentina is assigned to this genus and thus its geographical range is extended to the southeastern Pacific, at least during the Pliensbachian (Figs. 2A and 3f). A doubtful specimen from New Zealand could perhaps also be added (material seen at Otago University, see Damborenea and Manceñido, 1992). This is then another pectinacean genus with a seemingly bipolar distribution during at least part of Early Jurassic times. Kolymonectes coloradoensis only occurs in very fine grained, mostly light-coloured sediments, forming beds with a great abundance of specimens. They are rare, though, in black shales and seem to have preferred open sea conditions. Populations from different localities differ greatly in mean shell size and I think this is related to depth and/or oxygen availability rather than temperature or other latitude-controlled factors. Larger sizes are attained at greater depth and/or less water turbulence, the only accompanying fauna being ammonites. Young individuals were probably byssally attached but the byssal notch became obsolete in adults and was then probably not functional. Adults are supposed to have lived resting on the substrate and have been very good swimmers. Ochotochlamys Milova and Polubotko (in Bychkov et al., 1976; Milova, 1976) is a closely related genus characterized by unequal auricles and the deep byssal notch retained in the adult shell.»
DAMBORENEA, S. E. 1993. Early Jurassic South American pectinaceans and circum-Pacific palaeobiogeography. Palaeogeography, Palaeoclimatology, Palaeoecology, 100: 109-123, figs. 1-4. [p. 114, 115]
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