Pachydiscus (Pachydiscus) neubergicus Hauer 1858 from: Ifrim, C..Stinnesbeck, W..Schafhauser, A.. (2005): Maastrichtian shallow-water ammonites of northeastern Mexico . Revista Mexicana de Ciencias Geológicas Vol. 22(1) p. 48-64 | . |
Notice: This catalogue page may contain unedited data.
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Species Pachydiscus (Pachydiscus) neubergicus Hauer 1858 |
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[1] 4a-b Ifrim et al. (2005) [2] 4c Ifrim et al. (2005) [3] 5h Ifrim et al. (2005)
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| Alternative name: |
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| Diagnosis / Definition: |
Ifrim et al. (2005):
DESCRIPTION.
The shell is moderately involute and expands
at a moderate rate. The test is little compressed, with a
WB/WH ratio of about 0.85. The umbilicus spans 29%
of the diameter. The vertical umbilical wall arches widely
into slightly convex and convergent flanks. Greatest
whorl breadth is below mid-flank. The venter is widely
rounded. The flanks display approximately six sigmoidal
primary ribs per half whorl. The ribs are concave on the
umbilical shoulders, rectiradiate on the dorsal flank, and
they bend convexly backwards at mid-flank. They cross
the ventrolateral shoulders in a wide concavity and weaken
towards the venter. Up to a diameter of about 9 cm, the two
ventrolateral secondary ribs are parallel to the primaries. At a diameter of 10 cm, the shell displays at least one secondarybetween each primary rib. At a shell diameter of 12 cm, the primary ribs flatten and become straighter on the outer flanks, while secondary ribs are more distant and seem to weaken. Unfortunately the shell is badly weathered and crushed in this part. The suture line is partially visible and corresponds to that of the genus.
FATMI & Kennedy (1999):
Description. -GSP 1046: crushed composite mold 80 mm in diameter, wholly septate, moderately involute, with U = 21 percent of diameter, umbilical wall low, umbilical shoulder more narrowly rounded, inner flanks feebly convex, outer flanks convergent, ventrolateral shoulders and venter broadly rounded. An estimated 12 primary ribs per whorl arise on umbilical wall and strengthen into narrow concave bullae on ventrolateral shoulder that give rise to single narrow, distant prorsiradiate ribs that may branch. Intercalated ribs arise on outer flank and all ribs strengthen across venter to give 25 ribs per half whorl at ventrolateral shoulder at greatest diameter preserved. Types. -Lectotype.. by the subsequent designation of de Grossouvre, 1894, p. 209, is the original of Hauer, 1858, p. 12, pl. 2, figs. 1, 2, no. 1858.01.6 in the collections of the Geologisches Bundesanstalt, Vienna. Three paralectotypes have the same inventory number; all of the types are from the Lower Maastrichtian of Neuberg, Steiermark, Austria. |
| Discussion / Comments: |
Ifrim et al. (2005):
TYPE.
The lectotype is GBA 1858.01.6, which comes from
the Early Maastrichtian of Neuberg, Steiermark, Austria. It
is the original of Hauer, 1858, pl. 2, figs. 1-3, by subsequent
designation of Grossouvre, 1894, p. 209. The specimen was
refigured by Kennedy and Summesberger, 1986, pl. 3, figs. 1-3,
and Kennedy, 1986, pl. 4, fig. 3.
Material. One deformed, weathered specimen from the
base of the middle member of the Cárdenas Formation at
the railway section east of Cárdenas.
DISCUSSION.
Pachydiscus (Pachydiscus) neubergicus Hauer
from the Mexican Cárdenas Formation presents the slightly
compressed whorl section of the type material of P. (P.)
neubergicus (Hauer, 1858), although ornamentation is
more typical of P. (P.) jacquoti Seunes (1891) with one
or two ventrolateral rib between two moderately distant
primary ribs.
The type material of Pachydiscus (Pachydiscus)
neubergicus is slightly compressed, with a WB/WH ratio
between 0.72 and 0.78. Shape of its primary ribs corresponds
to that observed in our specimen, with nine primary ribs
per half whorl in the Mexican specimen and in the type
material, but it differs in the higher number of secondary
ribs: eighteen per half whorl in the lectotype, whereas
thirteen are recognized in the last half whorl of the
Mexican specimen (but at this diameter our specimen is
larger than the lectotype). P. (P.) neubergicus is
subdivided into two subspecies which differ in ornamentation
of adult shells.
See Henderson and McNamara (1985), Kennedy and
Summesberger (1986), and Ward and Kennedy (1993) for
discussion of subspecies.
Pachydiscus (Pachydiscus) jacquoti Seunes is
also similar. In this species, 10 to 12 primary ribs are
present per whorl with one or two ventrolateral ribs, and
ornamentation is comparable to that of our specimen.
However, whorl section of the type material is considerably
less compressed in P. (P.) jacquoti than in our specimen, and
the WB/WH ratio of Pachydiscus (Pachydiscus) jacquoti
is 0.95 to 1.20, compared to a WB/WH ratio of 0.85 in the
Cárdenas specimen. None of the subspecies of Pachydiscus
(Pachydiscus) jacquoti are close to our specimen. They
differ in ornamentation during late ontogeny (Henderson and
Mcnamara, 1985; Kennedy, 1986; Stinnesbeck, 1986; Ward
and Kennedy, 1993). The higher density of ventrolateral ribs,
the shape of primaries and a similar whorl section relate
the Cárdenas species closer to P. (P.) neubergicus than to
P. (P.) jacquoti, although the density of the primary ribs
is less than that of P. (P.) neubergicus. The disappearance
of secondary ribbing is most probably an artifact due to
mechanical abrasion, because faint traces of ribs remain
visible on the shell of our specimen.
Material. One deformed, weathered specimen from the
base of the middle member of the Cárdenas Formation at
the railway section east of Cárdenas.
Occurrence. All species discussed below are Maastrichtian
in age. Pachydiscus (P.) neubergicus, which appears to be
conspecific with our specimen, is the index fossil for the
Early Maastrichtian (Christensen et al., 2000; Odin and
Lamaurelle, 2001). In North America, the species was
recorded only once from the Navesinsk Formation of New
Jersey (Kennedy et al., 2000).
FATMI & Kennedy (1999):
Discussion.-Two subspecies have been recognized in Pachydiscus neubergicus. In the nominate subspecies, which ranges from Lower to lower Upper Maastrichtian, specimens at the ontogenetic stage corresponding to the present specimen have 1417 umbilical bullae, and 48 to almost 60 ribs at the ventrolateral shoulder. Subspecies dissitus Henderson and McNamara, 1985 (p. 72, pl. 7, figs. 7, 9; pl. 10, figs. 3-6; text-figs. 11, 12c, 13c) of the upper Upper Maastrichtian cannot be separated from the nominate subspecies at this diameter, but adults of the two differ in that neubergicus neubergicus has numerous primary ribs separated by single secondary or intercalated ribs or not, whereas neubergicus dissitus has many more ventral than umbilical ribs. Having only a juvenile, we cannot identify the present specimen to subspecific level. See Kennedy and Summesberger (1986), Henderson and McNamara (1985), and Ward and Kennedy (1993), for a comprehensive synonymy and discussion of the species and subspecies.
Ward & Kennedy (1993):
Discussion. -
Juvenile Pachydiscus (P.) neubergicus that are
too small to be referred either to the nominate subspecies or to
dissitus of Henderson and McNamara (1985) occur well above
the upper range limit of P. (P.) neubergicus neubergicus at Hendaye
and Bidart. They probably represent the upper Maastrichtian
subspecies dissitus, but in the absence of adult whorls, we
cannot be certain.
Occurrence.-
In the Biscay sections this taxon is found in
Member IV (upper Maastrichtian). |
| Systematics: |
36
Ordo Ammonoidea
Subordo Ammonitina
Superfamilia Desmocerataceae
Familia Pachydiscidae
Genus Pachydiscus
Species Pachydiscus (Pachydiscus) neubergicus
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Ordo Ammonoidea
Subordo Ammonitina
Superfamilia Desmocerataceae
Familia Pachydiscidae
Genus Pachydiscus
Subgenus Pachydiscus
Species Pachydiscus (Pachydiscus) neubergicus
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Ordo Ammonoidea
Subordo Ammonitina
Superfamilia Desmocerataceae
Familia Pachydiscidae
Genus Pachydiscus
Subgenus Pachydiscus
Species Pachydiscus (Pachydiscus) neubergicus
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Ordo Ammonoidea
Subordo Ammonitina
Superfamilia Desmocerataceae
Familia Pachydiscidae
Subgenus Pachydiscus (Pachydiscus)
Species Pachydiscus (Pachydiscus) neubergicus
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| Synonym list: |
Ifrim et al. (2005):
1858 Ammonites Neubergicus Hauer. - Hauer : p.12 pl. 2, figs. 1-3 [non pl. 3, figs. 1-3 = Pachydiscus epiplectus
(Redtenbacher, 1873)]
1986 Pachydiscus (Pachydiscus) neubergicus Hauer. - Kennedy & Summesberger : p.189 pl. 2, figs. 1-2; pl. 3, figs. 1-3; pl. 4, figs. 1-5; pl. 5, figs. 1,4-5; pl. 6, figs. 1-2,5; pl. 15, figs. 7-8; fig. 5a,b (with full synonymy)
1986 Pachydiscus (Pachydiscus) neubergicus Hauer. - Kennedy & Summesberger : p.199 pl. 2, figs. 1, 2; pl. 3, figs. 1-3; pl. 4, figs. 1-5; pl. 5, figs 1, 4, 5; pl. 6, figs. 1, 2, 5; pl. 15, figs. 7, 8, text-fig. 5a, b (with full synonymy)
1993 Pachydiscus (Pachydiscus) neubergicus neubergicus Hauer. - Ward & Kennedy : p.30 figs. 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
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| Was used in synonym list of: |
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| Stratigraphy - relative ages: |
Maastrichtian: Ifrim et al. (2005)
upper Maastrichtian - upper Maastrichtian: Ward & Kennedy (1993)
upper Maastrichtian - lower Maastrichtian: FATMI & Kennedy (1999)
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| References: |
Forbes,E.. (1846):
Report on the Cretaceous fossil invertebrates from southern India, collected by Mr. Kaye and Mr. Cunliffe . Transactions of the Geological Society of London Vol. 2(7) p. 97–174
Hauer,F.. (1858):
Über die Cephalopoden der Gosauschichten . Beiträge zur Paläontologie von Österreich Vol. 1 p. 7-14
Kennedy,W.J.. (1986):
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
Kennedy,W.J.. and Henderson,R.A.. (1992):
Non-heteromorph ammonites from the Upper Maastrichtian of Pondicherry, south India . Palaeontology Vol. 35 p. 381-442
Kennedy,W.J.. and Hancock,J.M.. (1993):
Upper Maastrichtian ammonites from the Marnes de Nay between Gan and Rebenacq (Pyrenees-Atlantiques), France . Geobios Vol. 26 p. 575-594
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
Ward,P.D.. and Kennedy,W.J.. (1993):
Maastrichtian ammonites from the Biscay Region . Journal of Paleontology Vol. 67(5 II) p. 1-58
Ward,P.D.. and Orr,W.. (1997):
Campanian-Maastrichtian ammonite and planktonic foraminiferal biostratigraphy from Tercis, France: implications for defining the stage boundary. . Journal of Paleontology Vol. 71 p. 407-418
FATMI,A.N.. and Kennedy,W.J.. (1999):
Maastrichtian ammonites from Balochistan, Pakistan. . Journal of Paleontology Vol. 73(4) p. 641-662
Kennedy,W.J..; Landman,N.H..; Cobban,W.A.. and Johnson,R.O.. (2000):
Additions to the ammonite fauna of the Upper Cretaceous Navesinsk Formation of New Jersey . American Museum Novitates Vol. 3306 p. 1–30
Ifrim,C..; Stinnesbeck,W.. and Schafhauser,A.. (2005):
Maastrichtian shallow-water ammonites of northeastern Mexico . Revista Mexicana de Ciencias Geológicas Vol. 22(1) p. 48-64
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