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Subvarietas Acanthoscaphites (Euroscaphites) varians blaszkiewiczi Jagt et al. 1999 | ||||||
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| Discussion / Comments: | ||||||
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Machalski (2005): TYPE MATERIAL.- The specimen in Birkelund (1993: pl. 10: 3) from the up− per lower or lower upper Maastrichtian of Rørdal, Jylland, is holotype (see Fig. 22A). It is numbered MGUH 20129A herein to avoid confu− sion as two specimens referred to Acanthoscaphites varians (Łopuski, 1911) by Birkelund (1993) erroneously bear the same number, MGUH 20129 (Birkelund 1993: pl. 9: 7; pl. 10: 3). MATERIAL.- From Germany: four specimens from Hemmoor (GPIUH 821–823, NLfB kma 179). From Denmark: eight specimens from Rørdal (MGUH 20125, 20126, 20128, 20129, 20129A, 27750, MGUH 1973. 841, 844). From Bel− gium: one specimen from the CPL quarry, Haccourt (NHMM 198840−1–3, ex Jagt collection), and one from the CBR−Lixhe quarry, Lixhe (NHMM MB 1147). From Poland: one speci− men from Chełm (ZPAL Am. 12/372). Additionally, a speci− men MWGUW ZI/35/147 of unknown provenance (ex Ma− kowski collection). DISCUSSION.- According to Jagt et al. (1999), the present subspecies differs from the later Acanthoscaphites (Euro− scaphites) varians varians in retaining multiple tubercula− tion on macroconch body chambers, especially the ventral row and two rows of outer flank tubercles (Fig. 22). Only on the youngest parts of the body chamber in specimens from Denmark has the loss of some rows of tubercles been ob− served (Birkelund 1993; Jagt et al. 1999; Fig. 22A). How− ever, this process starts with the inner flank tuberculation, in contrast to material of A. (E.) v. varians in which the siphonal row is the first to be lost. The best−preserved specimens of A. (E.) v. blaszkiewiczi come from Rørdal, Jylland, either from the upper lower Maastrichtian Rugia tenuicostata–Meonia semiglobularis Zone or from the lower upper Maastrichtian Meonia semi− globularis–Ruegenella humboldtii Zone (Birkelund 1993; Jagt et al. 1999). The remainder of the material studied co− mes from the upper lower to lower upper Maastrichtian at Hemmoor (Schmid 1965; Birkelund 1982), and in the Haccourt−Lixhe area in Belgium (Jagt and Kennedy 1989; Jagt et al. 1999). The latter records, from units 5–6 of the Vijlen Member (Gulpen Formation) as exposed at the CBR− Lixhe and CPL quarries were assigned to the Belemnitella ju− nior Zone of authors by Jagt and Kennedy (1989) and Jagt et al. (1999) and claimed to be of early late Maastrichtian age. However, recent work on inoceramid bivalves places this in− terval within the upper lower Maastrichtian “Inoceramus” morgani Zone (Ireneusz Walaszczyk and John W.M. Jagt, unpublished data). Acanthoscaphites cf. verneuilianus (d’Orbigny, 1841) of Kennedy (1986: 74, pl. 16: 20, 21), from the “Calcaire à Baculites” of Cotentin, is also assigned here, albeit with a query. The specimen bears siphonal tubercles and feeble um− bilical and lateral bullae, plus strong inner and outer ventro− lateral tubercles (Kennedy 1986: 76), being thus very close in its ornament to A. (E.) varians blaszkiewiczi. Also its um− bilicus is of comparable diameter to that of A. (E.) varians blaszkiewiczi (compare Kennedy 1986: pl. 16: 20, 21 and Fig. 25C herein). The only specimen from Chełm assigned to A. (E.) v. blaszkiewiczi is a fragment of body chamber ZPAL Am. 12/372 from level III. It belonged to a large specimen, presum− ably amacroconch, and shows four distinct tubercles arranged in two rows. Only one row of umbilicolateral tubercles per− sists to the early part of the body chamber in A. (E.) v. varians. Another specimen, MWGUW ZI/35/147 (Fig. 23A1, A2) comes from the former collection of Henryk Makowski at the Geology Department at Warsaw University and lacks prove− nance data. MWGUWZI/35/147 is preserved in opoka, typi− cal of Maastrichtian deposits outcropping in the Lublin and Miechów uplands. Two samples of the matrix of the speci− men MWGUW ZI/35/147 have been investigated for its nannofossil content by Jackie Lees (personal communication July 2005). Both samples contain Arkhangelskiella maas− trichtiana. The first occurrence of A. maastrichtiana defines the base of Nannofossil Subzone UC20cBP in the lower up− per Maastrichtian (Burnett 1998). The samples also contain Nephrolithus frequens and Lithraphidites quadratus, the first occurrences of which mark the underlying subzones in the lower upper Maastrichtian. In contrast, Cribrosphaerella daniae, which marks the base of the younger subzone, UC20dBP in the upper upper Maastrichtian, was missing in both samples studied. In summary, MWGUW ZI/35/147 is no older than early late Maastrichtian, and may be as young as late late Maastrichtian (Jackie Lees, personal communica− tion July 2005). MWGUWZI/35/147 is amacroconch with the adapertural part of the shaft and the final hook missing (Fig. 24). The spec− imen is 165 mm in maximum preserved diameter. The orna− ment of the preserved part of the shaft and the exposed part of the spire ofMWGUWZI/35/147 consists of seven rows of tu− bercles: three on the flank and one on the venter. Additionally, umbilical bullae ofmoderate strength are visible on the umbil− ical shoulder. The ventrolateral and siphonal tubercles are stronger than the remaining tubercles. There is no sign of fad− ing away of the tubercles at the adapertural part of the pre− served part of the shaft. Thus, MWGUW ZI/35/147 matches in its tuberculation the best−preserved individuals of Acanthoscaphites (E.) v. blaszkiewiczi as described by Schmid (1965), Birkelund (1993) and Jagt et al. (1999). However, the tubercles are more robust and more widely spaced in MWGUW ZI/35/147 than in the remainder of the material. There are also differences in ribbing between specimen MWGUW ZI/35/147 and the remaining material of A. (E.) v. blaszkiewiczi studied. In the latter specimens, the primary tu− berculate ribs are separated by one or two, exceptionally three, thin and nontuberculate secondaries. In MWGUW ZI/35/147 the interprimary intervals are much wider and contain three secondaries each (Figs. 23, 24).Moreover, the secondaries are set at an acute angle to the succeeding primary rib, as if they arose from the adapical face of that primary. This recalls the ribbing in the holotype of A. (E?) verneuilianus (d’Orbigny, 1841) as described in Kennedy (1986) and below. The above−mentioned differences in ornament suggest that specimen MWGUW ZI/35/147 is an end−member of the population of Acanthoscaphites (E.) v. blaszkiewiczi. Alter− natively, it could be described as a new species. This matter cannot be resolved, however, with only a single specimen of unknown provenance at hand. Contrary to Birkelund (1993) and Jagt et al. (1999), no microconchs exist which could be convincingly matched with macroconchs of Acanthoscaphites (E.) v. blaszkiewiczi in terms of style of ribbing and number of tubercles. The pur− ported microconchs of this subspecies (Jagt et al. 1999: pl. 8: 1, 5, the latter refigured in Fig. 25B) differ from specimens of A. (E.) v. blaszkiewiczi of similar size (Birkelund 1982: pl. 1: 5, refigured in Fig. 25C; Fig. 25E) and are better assigned to a separate taxon: Acanthoscaphites (Euroscaphites?) sp. aff. verneuillianus (d’Orbigny, 1841) (see discussion below). STRATIGRAPHIC RANGE.- Upper lower and/or lower upper Maastrichtian of northern Germany (Belemnella cimbrica to Tenuipteria argentea–Belemnitella junior zones), Belgium (“Inoceramus” morgani Zone), Denmark (Rugia tenuicostata–Meonia semiglobularis and Meonia semiglobu− laris–Ruegenella humboldtii zones), and Poland (Spyrido− ceramus tegulatus–Belemnitella junior Zone). |
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| Systematics: | ||||||
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51 Species Acanthoscaphites (Euroscaphites) Subvarietas Acanthoscaphites (Euroscaphites) varians blaszkiewiczi |
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| Synonym list: | ||||||
| Machalski (2005): 1965 Acanthoscaphites tridens varians Lopuski. - Schmid : p.684 pl. 62, fig. 1;
pl. 63, fig. 1-3
p 1982 Acanthoscaphites varians Lopuski. - BIRKELUND : p.16 pl. 1; fig. 4 [non pl. 1, fig. 4 = Hoploscaphites sp. ex gr.
pungens-schmidi; non pl. 1, fig. 6 = Hoploscaphites
schmidi]
? 1986 Acanthoscaphites cf. verneuilianus d'Orbigny. - Kennedy : p.74 pl. 16; fig. 20, 21
1989 Acanthoscaphites varians Lopuski. - Jagt & Kennedy : p.238 fig. 1-3
p 1993 Acanthoscaphites varians Lopuski. - BIRKELUND : p.56 pl. 9, fig. 3, 4, 6, 7;
pl. 10, fig. 3 [non pl. 9, fig. 5; pl. 10, fig. 2 =
Acanthoscaphites (Euroscaphites?) sp. aff.
verneuilianus]
p 1999 Acanthoscaphites n spp. (Euroscaphites) varians blaszkiewiczi Jagt et al.. - Jagt et al. : p.139 text-fig. 5, 6;
pl. 8, fig. 2-4, 6 [non pl. 8, fig. 1, 5 = Acanthoscaphites
(Euroscaphites?) sp. aff. verneuilianus]
non 2002 Acanthoscaphites (Euroscaphites) varians blaszkiewiczi Jagt et al.. - Reich & Frenzel : pl. 23; fig. 1a, b [?= Acanthoscaphites (Euroscaphites?) sp. aff.
verneuilianus]
2005 Acanthoscaphites (Euroscaphites) varians blaszkiewiczi Jagt et al.. - Machalski : p. 684, 685, 686, 68 fig. 22A, 23, 24, 25C, E
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| Was used in synonym list of: | ||||||
| Stratigraphy - relative ages: | ||||||
| upper Maastrichtian - lower Maastrichtian: Machalski (2005) |
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| References: | ||||||
Schmid,F.. (1965): BIRKELUND,T.. (1982): Kennedy,W.J.. (1986): Jagt,J.W.M.. and Kennedy,W.J.. (1989): BIRKELUND,T.. (1993): Jagt,W.J.M..; Kennedy,W.J.. and Machalski,M.. (1999): Reich,M.. and Frenzel,P.. (2002): Machalski,M.. (2005): |
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| Anonymous: Unedited TaxonConcept data | ||||||
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