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  • Oligophus moravicus (Pauca, 1931)


    Images:

    oilshale

    Taxonomy

    Lanternfish

    Kingdom: Animalia
    Phylum: Chordata Haeckel 1874
    Class: Actinopteri Cope 1871
    Order: Myctophiformes Regan 1911
    Family: Myctophidae Gill 1893
    Genus: Oligophus
    Species: Oligophus moravicus
    Author Citation (Pauca, 1931)

    Geological Time Scale

    Eon: Phanerozoic
    Era: Cenozoic
    Period: Paleogene
    Sub Period: None
    Epoch: Oligocene
    International Age: Rupelian

    Stratigraphy

    Menilite Krosno Group
    Menilite Formation

    Provenance

    Acquired by: Purchase/Trade

    Dimensions

    Length: 68 mm

    Location

    Futoma (Village)
    Rzeszów (County)
    Subcarpathian Voivodeship (Province)
    Poland

    Comments

    Alternative combinations: Diaphus moravicus and Leuciscus moravicus.

    Taxonomy according to Fossilworks.org.

    Description of Oligophus moravicus according to Přikryl et al. 2017, pp. 219-220: “The following description is based on the almost complete specimen Tv 1023a and its counterpart specimen Tv 1023b. They show a preorbital length much shorter than orbit diameter. The head is rounded, with an antero-dorsally oriented mouth. The lower jaw joint is located far posterior to the posterior-most margin of the orbit. The maxillary is slender throughout. There is no indication of a supramaxilla. The cleithrum seems to be delicate without well-developed posterior lamina. The vertebral column is not completely preserved in any of the specimens, but the total number of vertebrae seems to be 34 or 35. Remains of ventral procurrent rays are recognizable and therefore the vertebral number cannot have been much higher; about 16 centra are abdominal. Nine pairs of ribs are preserved. The pectoral fins are long, reaching the level of the posterior third of the abdomen, and are composed of about 13 rays. The pelvic fins are located below the dorsal-fin insertion and consist of seven or eight rays; the pelvic girdle is inadequately preserved. The dorsal fin is located at midlength of the body length and is composed of slightly more than 11 rays. The anal fin contains 12 or 13 rays. The body is covered by cycloid scales.

    The individual photophores are slightly thickened and although the complete photophore formula is not recognizable, a reconstruction of the preserved part shows the pattern reported in Figs. 3 and 4. The fish is slightly distorted midventrally, so that the photophores of the right side area appear to be located higher than on the left side (colour-coded in Fig. 3). The photophores appear to be lens-like. There are faint indications of two photophores just above and below the pectoral-fin base which could represent the PLO and the upper PVO. The four rear PO are preserved, with PO4 being slightly elevated. Five VO, none of them elevated, and three SAO are clearly discernable, the three SAO being located on a straight upward directed line. The AO sequence is apparently incomplete posteriorly and appears to be separated in an anterior and a posterior part. Other photophores are not clearly recognizable.

    The inner faces of both the saccular otoliths of the specimens Tv 1023a and Tv 1023b are exposed (Fig. 5A, B). The overall outline of the otolith is moderately elongate with a long rostrum, a depressed predorsal rim, a strongly developed and far backward positioned postdorsal angle, a blunt posterior rim and a regularly bent ventral rim. The length to height ratio of the otolith is 1.2 to 1.3. The ventral rim bears 7 strong denticles. The length of the rostrum is about 15% of the otolith length; excisura and antirostrum are weak. The inner face shows a slightly supramedian positioned sulcus with the ostium being longer but slightly narrower than the cauda. The ratio between the length of ostium and cauda is 1.3-1.5. A ventral pseudocolliculum is well developed below the caudal colliculum. The dorsal field bears a large dorsal depression; the ventral field shows a distinct ventral furrow at some distance from the ventral rim of the otolith. The inner face is nearly flat. The outer face is exposed in the specimen Tv 1025 and is distinctly convex and smooth with a postcentral umbo.”

    Line drawing of Oligophus moravicus from Přikryl et al, 2017, p. 220.

     Oligophus moravicus line drawing

    Identified by oilshale using Přikryl et al. 2017. 

    References:

    Pauca, M. (1931): Zwei Fischfaunen aus den oligozaenen Menilitschifern von Mähren. Annalen des Naturhistorischen Museums in Wien 46: 147-152.

    Prokofiev, A. M. (2006): Fossil Myctophoid Fishes (Myctophiformes: Myctophoidei) from Russia and Adjacent Regions. Journal of Ichthyology 46 (Suppl. 1): S38-S83. DOI: 10.1134/S0032945206100043

    Gregorova, R. (2004): A new Oligocene genus of lanternfish (family Myctophidae) from the Carpathian Mountains. Revue de Paléobiologie, Genève 9: 81-97.

    Přikryl, T., Schwarzhans, W., Kovalchuk, O. (2017): Lanternfishes (Myctophidae) with otoliths in situ from the Early Oligocene of the Eastern Paratethys (western Ukraine). Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 285 (2): 213-225. https://doi.org/10.1127/njgpa/2017/0678



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