Pachydiscus (Pachydiscus) neubergicus neubergicus Hauer 1858 from: Ward, P.D..Kennedy, W.J.. (1993): Maastrichtian Ammonites from the Biscay Region (France, Spain) . Memoir (The Paleontological Society), Journal of Paleontology34 (Supplement to Vol. 67)(5) p. 1-58
|Notice: This catalogue page may contain unedited data.
Subspecies Pachydiscus (Pachydiscus) neubergicus neubergicus Hauer 1858
|Diagnosis / Definition:
Ward & Kennedy (1993):
Biscay specimens up to 160 mm diameter.
Coiling relatively involute with approximately two-thirds of
previous whorl covered, whorls expanding at moderate rate.
Umbilicus comprises around 30 percent of diameter, with low,
rounded wall. All specimens crushed, and whorl section cannot
be determined, although it seems to have been compressed, with
rounded inner flanks, convergent outer flanks and rounded venter.
Middle growth stages have 14-16 primary ribs per whorl.
These arise at umbilical seam, sweep back, strengthen, and are
concave on umbilical wall and develop into distant umbilical
bullae. These are straight and prorsiradiate at smallest diameter
seen, but become distinctly concave as size increases. Bullae
extend across inner third of flanks, weakening, and passing into
one or two ribs, which increase by branching and intercalation
and sweep slightly forwards to cross venter in shallow convexity.
There are from 20 to 27 ventral ribs per half whorl at this stage.
As size increases, bullae weaken, and long primary ribs become
more numerous, separated by single secondaries or not, ribbing
weakening markedly over venter.
|Discussion / Comments:
Ward & Kennedy (1993):
Lectotype is No. 1858.1.6 in the collections of the
Austrian Geological Survey, the original of Hauer, 1858, p. 12, Pl. 2, figs. 1, 2, from Neuberg, Steiermark, Austria, designated by de Grossouvre, 1894, p. 209.
Kennedy and Summesberger (1986) described
and illustrated the lectotype (Figure 28.1-28.3) and a series of
topotypes of Pachydiscus (P.) neubergicus neubergicus, and the
Biscay material differs in no significant respects from their material.
Henderson and McNamara (1985, p. 72, Pl. 7, figs. 7, 9,
Pl. 10, figs. 3-6, text-figs. 1 1, 12c, 13c) described, as subspecies
dissitus, a distinctive form from the upper Maastrichtian of
western Australia. This has inner whorls like those of the nominate
subspecies but the outer whorl, rather than having mainly
primary ribs, has many more ventral than umbilical ribs, in this
respect resembling P. (P.) gollevillensis (d'Orbigny, 1850) (p. 212; see Kennedy, 1986c, p. 28, Pls. 1-3, Pl. 4, figs. 4-6, Pl. 5, figs. 12-14,20-24, Pl. 11, figs. 1-5, text-figs. 2,3p, r, 4c). Indeed, Spath (1941, p. 45, Pl. 2, fig. 1) identified a fragment of P. (P.)
neubergicus dissitus as Pachydiscus aff. gollevillensis. Differences between P. (P.) neubergicus neubergicus and other species are
reviewed at length by Kennedy and Summesberger (1986) and
are not discussed further here. When compared to other species in the Biscay fauna, P. (P.) gollevillensis (Figure 32) has 9-11
umbilical bullae and approximately 80 ribs per whorl, fewer
bullae but more ribs than P. (P.) neubergicus neubergicus. Pachydiscus (P.) armenicus Atabekian and Akopian, 1969 (p. 8, Pl. 1, fig. 2, Pl. 3, figs. 1, 2; see Figure 34.1-34.6) in contrast has more (16-20) umbilical and ventral ribs (6 2-7 3). Pachydiscus (P.) jacquoti (Seunes, 1890b) (p. 5, Pl. 3(2), figs. 1-3) as revised
by Kennedy (1986c, p. 34, Pl. 5, figs. 3-1 1, 15-19, Pl. 6, textfigs. 2d, e, 30, s, 4b) is easily separated. The whorls are lower,
slowly expanding and subcircular when uncrushed, the shell
having a wider umbilicus, with U in excess of 30 percent, few, distant primary ribs, and coarser, very distant ventral ornament.
Pachydiscus (P.) epiplectus (Redtenbacher, 1873) (p. 12 1, Pl. 28, fig. 1) (Figure 28.4,28.5) and P. (P.) terminus sp. nov., described below, are both much more massive shells with dense ribbing.
In the Biscay sections this taxon ranges from
low in Member I (lower Maastrichtian) to low in Member IV
(upper Maastrichtian). Elsewhere, the nominate subspecies ranges
from low in the lower Maastrichtian to low in the upper Maastrichtian,
with records from Tercis, Landes, France, north Germany,
Denmark, Austria, Poland, the Ukrainian SSR, Armenian
SSR, European Russia, Nigeria, Zululand (South Africa),
Madagascar, and south India. Subspecies dissitus is restricted
to the upper Maastrichtian of western Australia.
|Ward & Kennedy (1993):
1986 Pachydiscus (Pachydiscus) neubergicus Hauer. - Kennedy & Summesberger
: p.189 pl. 2, fig. 1, 2;
pl. 3, fig. 1-3;
pl. 4, fig. 1-5;
pl. 5, fig. 1, 4, 5;
pl. 6, fig. 1, 2, 5;
pl. 15, fig. 7, 8;
text-fig. 5a, b (with full synonymy)
1993 Pachydiscus (Pachydiscus) neubergicus neubergicus Hauer. - Ward & Kennedy
: p. 27, 32, 33, 36 fig. 25.9, 25.10, 25.11, 25.12, 25.14, 25.16-25.18, 27.3-27.5, 27.7, 28.1-28.3, 30.4, 30.6
|Was used in synonym list of:
|Stratigraphy - relative ages:
|upper Maastrichtian - lower Maastrichtian: Ward & Kennedy (1993)
|Collection of the Austrian Geological Survey, Inventory number: No. 1858.1.6
Über die Cephalopoden der Gosauschichten . Beiträge zur Paläontologie von Österreich Vol. 1 p. 7-14
The ammonite fauna of the Calcaire à Baculites (Upper Maastrichtian) of the Cotentin Peninsula (Manche, France) . Palaeontology Vol. 29(1) p. 25-83
Kennedy,W.J.. and Summesberger,H.. (1986):
Lower Maastrichtian ammonites from Neuberg, Steirmark, Austria: . Beiträge zur Paläontologie von Österreich Vol. 12 p. 181–242
Die Oberkreide-Ammoniten (Maastricht) aus dem Abteufen des keinzichschachts der Grub Staric (Unterschlesian Decke, Äussere-Karpaten) . Acta Musei Moraviae, Scientiae Naturalas Vol. 73 p. 71-81
Ward,P.D.. and Kennedy,W.J.. (1993):
Maastrichtian Ammonites from the Biscay Region (France, Spain) . Memoir (The Paleontological Society), Journal of Paleontology34 (Supplement to Vol. 67)(5) p. 1-58
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