Ochotochlamys Milova & Polubotko, 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. 69]
MILOVA, L. V. 1976. Triassic-Jurassic stratigraphy and Bivalvia of northern Priokhotye. Akademia Nauk SSSR, Trudy Severo-Vostcvnyi Kompleksnoyi Nauchno-Institut. Akademia Nauk SSSR 65: 110 p., pls. 1-16. (in Russian). [p. 61]
«Подрод Ochotochlamys МiIоvа еt Рolubotkо, subgеп. поv.
ПроисхожДение названия: по Охотскому побережью.
типовойвид. Chlamys (Ochotochlamys) gizhigensis Рolubotkо, sp. nov. Норийский ярус, зона Otapiria ussurieпsis. Бассейн р. Гижиги, р. Малая Туромча.
Диагноз. Раковина почти округлого очертания с умеренно и одинаково выпуклыми створками, из которых левая несет радиальную скульптуру от тонкой до довольно грубой, а правая либо гладкая, либо е резко ослабленной, едва заметной радиальной скульптурой. Ушки, как у Chlamys, но меньше разнящиеся по величине, иногда почти равновеликие; под передним ушком правой створки имеется неглубокий, нногда ед,ва заметный бисеусный вырез. Левая створка снабжена боковыми депрессиями и сопутствующими ИМ вздутиями, из которых задние развиты значительно лучше, чем сла6ые передние, которые иногда совсeм неза'меl'НЫ.
Сравнение. От Chlamys, s. stricto, новый подрод отличается резко различной скульптурой створок н меньшей разницей в величине ушек. От подрода Camptochlamys отличается значитеаьно более грубой с!скульптурой левой створки, слабо развитым биссусным вырезом и более равновсликим иушками.
Видовойсостав: Ch. (Ochotochlamys) korkodonensis Роlub., sp. поv., Ch. (Ochotochlamys) gizhigensis Рolub., sp. поv., Ch. (Ochotochlamys) noricus Мilоvа, sp. поv.
Распространение. Верхнетриасовые и нижнеюрские отложения Северо-Востока СССР.»
LYDIA VASILEVNA MILOVA & INGA VLADIMIROVNA POLUBOTKO, 1976
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Chlamys (Ochotochlamys) gizhigensis Рolubotkо, sp. nov.; Y. M. Bychkov, A. S. Dagys, A. F. Efimova & I. V. Polubotko, 1976, Atlas of the Triassic Fauna and Flora of Northeastern USSR, plate 50, figures 1-6.
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S. Ros-Franch, A. Márquez-Aliaga & S. E. Damborenea, 2014, Comprehensive database on Induan (Lower Triassic) to Sinemurian (Lower Jurassic) marine bivalve genera and their paleobiogeographic record, figure 36.
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Genus OCHOTOCHLAMYS
Milova & Polubotko in Milova, 1976, p. 61 Type species.— Chlamys (Ochotochlamys) gizhigensis Polubotko in Milova, 1976, p. 61.
Remarks.— Ochotochlamys was erected as subgenus of Chlamys (Milova & Polubotko in Milova, 1976), but it was subsequently raised to genus level (Polubotko & Milova, 1986), which was followed by all later authors
Stratigraphic range.— Upper Triassic (Norian)–Lower Jurassic (Toarcian) (Milova & Polubotko in Milova, 1976; Aberhan, 1998a). For a long time, Ochotochlamys was only reported from Late Triassic of northeastern Asia, but it was later recorded from the Pliensbachian (Polubotko & Milova, 1986; Aberhan 1998a; Damborenea, 2002a) and from the Toarcian (Aberhan, 1998a).
Paleogeographic distribution.— Boreal (Fig. 36). It was originally believed that the genus was restricted to northeastern Asia, but new records from the Pacific margin (Canada and Argentina) (Aberhan, 1998a; Damborenea, 2002b) extended its paleogeographic distribution; but it is only known from high paleolatitudes. The Austral record is Pliensbachian and thus outside our study range (Damborenea, 2002a). It was also mentioned from the Triassic–Jurassic boundary beds of British Columbia (Wignall & others, 2007) and eastern Alberta (Asgar-Deen & others, 2003).
Boreal domain: Late Triassic: Carnian–Norian of northeastern Asia (Polubotko & Milova in Milova, 1976); Early Jurassic: Hettangian of northeastern Russia (Milova, 1988); Hettangian–Sinemurian of western Canada (Aberhan, 1998a, 1998b, 2001); Sinemurian of northeastern Russia (Polubotko & Milova, 1986). Paleoautoecology.— B, E, S, Epi, Sed; By. According to Aberhan (1998a), a typical feature of the genus is that the right anterior auricle had a byssal notch; a byssal sinus is observed in the left valve, but it is not distinguishable in all specimens. Ochotochlamys was probably an epibyssate bivalve.
Mineralogy.— Bimineralic (Carter, 1990a, p. 260). There are no data on Ochotochlamys shell microstructure. Bimineralic mineralogy is assumed, as in the other members of the family Pectinidae (Carter, 1990a).
ROS-FRANCH, S., A. MÁRQUEZ-ALIAGA & S. E. DAMBORENEA. 2014. Comprehensive database on Induan (Lower Triassic) to Sinemurian (Lower Jurassic) marine bivalve genera and their paleobiogeographic record. Paleontological Contributions, 8: 3-219, figs. 1-61. [p. 103]
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Chlamys (Ochotochlamys) gizhigensis Рolubotkо, sp. nov. (MS); L. V. Milova, 1976, Triassic-Jurassic stratigraphy and Bivalvia of northern Priokhotye, plate 8, figures 8-12.
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«Remarks: MILOVA & POLUBOTKO introduced the name Ochotochlamys as a subgenus of Chlamys in two almost simultaneous papers: in BYCHKOV et aI. (26/7/1976, p. 69) and in MILOVA (23/8/1976, p. 61). The first paper preceded the latter by a few days, and it also offers a more complete diagnosis. This is freely translated as follows:
"Shell of almost circular outline with valves moderately and equally convex. Left valve with delicate to fairly thick radial ornament but right valves smooth or with very faint radial lines. Chlamys-like auricles but less different in size than in that genus, sometimes almost subequal; below the anterior right valve auricle there is a shallow byssal notch, sometimes scarcely visible. Left valve with Iateral depressions and swellings, of which the posterior one is better developed, the anterior one being weak or even imperceptible" (BYCHKOV et al. 1976, p. 70). This genus was thought to be endemic to the Upper Jurassic-Lower Jurassic of northeast Asia (SEY & KALACHEVA 1988, p. 41) but since then it was found in Canada (ABERHAN 1998) and southern Argentina (DAMBORENEA 1997a, species doscribed herein) (Text-figs. 6-7). It is absent from peri-equatorial regions, for instance, it has not been found in southern Russia (ROMANOV 1985) or Europe. As stated by DAMBORENEA (1997b) the relationships of Ochotochlamys were poorly known and it was thought it could even belong to the Propeamussiidae, but the presence of a ctenolium indicates its inclusion within the Pectinidae s.s. Furthermore, it is probably related to the Hyalopecten Verrill group (DAMBORENEA 1997a), as shown by a direct comparison of the diagnosis of both genera (see above and in SCHEIN 1989, p. 77-78; DIJKSTRA 1995, p. 47). WALLER & MARINKOVICH (1992) stressed that Hyalopecten lacks antimarginal microsculpture and stated that it is closely related to Praechlamys.» DAMBORENEA, S. E. 2002. Early Jurassic bivalves of Argentina. Part 3: Superfamilies Monotoidea, Pectinoidea, Plicatuloidea and Dimyoidea. Palaeontographica Abteilung A, 265: 1-119 [p. 72]
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