ZOBODAT - www.zobodat.at Zoologisch-Botanische Datenbank/Zoological-Botanical Database Digitale Literatur/Digital Literature Zeitschrift/Journal: Austrian Journal of Earth Sciences Jahr/Year: 2017 Band/Volume: 110_1 Autor(en)/Author(s): Summesberger Herbert, Kennedy William James, Skoumal Peter Artikel/Article: On late Santonian ammonites from the Hofergraben Member (Gosau Group, Upper Cretaceous, Austria) 122-141 Austrian Journal of Earth Sciences Vienna 2017 Volume 110/1 122 - 141 DOI: 10.17738/ajes.2017.0009 On late Santonian ammonites from the Hofergraben Member (Gosau Group, Upper Cretaceous, Austria)_______________________________ Herbert SUMMESBERGER1)*), William J. KENNEDY2) & Peter SKOUMAL3) 1) Museum of Natural History Vienna, Burgring 7, 1010 Vienna, Austria; 2) Oxford University, Museum of Natural History, Oxford OX1 3PW, United Kingdom; 3) Bastiengasse 56, 1180 Vienna, Austria; *) Corresponding author, [email protected] KEYWORDS Ammonites; Late Cretaceous; Northern Calcareous Alps; Gosau Group; Hofergraben Member; Austria Abstract 11 ammonite taxa are described from the upper Santonian of the Hofergraben site (Gosau Group; Upper Austria): Pachydisci- dae gen. et sp. indet. juv., Placenticeras polyopsis (Dujardin, 1837), Placenticeras paraplanum Wiedmann, 1978, Placenticeras aff. maherndli Summesberger, 1979, Texanites quinquenodosus Redtenbacher, 1873, Eulophoceras jacobi Hourcq, 1949, Jouaniceras hispanicum Wiedmann, 1994, ? Jouaniceras sp., Eubostrychoceras acuticostatum (d’Orbigny, 1842), Glyptoxoceras crispatum (Mo- berg, 1885), Baculites fuchsi Redtenbacher, 1873. Jouaniceras hispanicum Wiedmann, 1994 and Eubostrychoceras acuticostatum (d’Orbigny, 1842) are recorded for the first time from the Gosau Group confirming the close connection with the Upper Creta- ceous of the Corbières (France: Kennedy in Kennedy et al. 1995). 11 Taxa Ammoniten aus dem oberen Santonium des Hofer- grabens (Gosau-Gruppe; Ober- österreich) werden beschrieben: Pachydiscidae gen. et sp. indet. juv., Placenticeras polyopsis (Du- jardin, 1837), Placenticeras para- planum Wiedmann, 1978, Plac- enticeras aff. maherndli Summes- berger, 1979, Texanites quinque- nodosus Redtenbacher, 1873, Eulophoceras jacobi Hourcq, 1949, Jouaniceras hispanicum Wiedmann, 1994, ? Jouaniceras sp., Eubostrychoceras acuticos- tatum (d’Orbigny, 1842), Glyp- toxoceras crispatum (Moberg, 1885), Baculites fuchsi Redten- bacher, 1873. Jouaniceras his- panicum Wiedmann, 1994 und Eubostrychoceras acuticostatum (d’Orbigny, 1842) werden zum ersten Mal aus der Gosau-Grup- pe erwähnt und bestätigen die nahe Beziehung zur Oberkreide der Corbières (Frankreich: Ken- nedy in Kennedy et al., 1995)._ 1. Introduction Figure 1: A. Schematic geological map of the Eastern Alps. Occurrences of Gosau Group sediments The Gosau Group successions (black), brick symbol: Northern Calcareous Alps. After Summesberger et al. (2017a). B. Local sketch map of parts of the Gosau Basin, with modifications after Summesberger et al. (2017a) indicating the locali- of the Northern Calcareous Alps ties mentioned in the text._______________________________________________________________ of Austria are well known for 122 Herbert SUMMESBERGER, William J. KENNEDY & Peter SKOUMAL their richness in macrofossils and for their contributions to Gosau Subgroup were deposited under shallow marine con- Upper Cretaceous stratigraphy (e.g. Summesberger, 1985; ditions. The highly fossiliferous Hofergraben Member and the Wagreich et al., 2009).________________________________ Sandkalkbank Member of the Hochmoos Formation record The late Santonian Sandkalkbank Member of the Hochmoos the end of this shallow marine period, which was followed in Formation is a distinct marker bed of about 20 metres thick- the Campanian by increasing subsidence and the deep wa- ness. It extends from the junction of the “elliptica” Graben (Gerth, ter deposits of the Upper Gosau Subgroup (Ressen Forma- 1961, fig. 3) with the Neffgraben (Russbach, Salzburg), conti- tion, Nierental Formation). The Maastrichtian to Eocene Zwie- nues along the slope of the Schattau (Russbach, Salzburg) turns selalm Formation marks the end of marine sedimentation around the Bibereck where it appears in the “Finstergraben- wandl”. On the opposite side of the Gosau valley it loses its dis- tinct character and terminates in the Hofergraben (Gosau, Up- per Austria). The fauna of the Sandkalkbank Member was described by Wiedmann (1978: ammonites), Summesberger (1979, 1980: ammonites), Koll- mann (1980: gastropods), Dhondt (1984: bivalves) and Summes- berger et al. (2017c: ammonites). The Hofergraben Member of the Hochmoos Formation, under- lying the Sandkalkbank Mem- ber, is well-known for the ex- cellent preservation of abun- dant bivalves (e.g. the type spe- cimen of Cordiceramus muelleri (Petrascheck, 1906); fide Dhondt, 1987) and gastropods (Zekeli, 1852; Zittel, 1865–1866; Felix, 1908). In this paper cephalopods from the Hofergraben are descri- bed augmenting the previously described late Santonian cepha- lopod faunas noted above. 2. Geological Setting The Hofergraben locality is si- tuated in the Upper Austrian part of the Gosau Basin. The Go- sau Basin exposes a sedimenta- ry sequence, the Gosau Group, that ranges from Upper Turo- nian to Eocene. It begins with terrestrial conglomerates (the Kreuzgraben Formation) and coal bearing strata of the Neu- alm (Salzburg), where the am- monite Barroisiceras haberfell- neri (Hauer, 1858) indicates a late Turonian age. The early San- tonian Grabenbach and Hoch- Figure 2: Composite section of the Gosau Group in the Gosau area indicating the position of the Hofer- moos formations of the Lower graben Member (with revisions after Summesberger et al. 2017c)._______________________________ 123 On late Santonian ammonites from the Hofergraben Member (Gosau Group, Upper Cretaceous, Austria) (Wagreich and Decker, 2001). fig. 58- 61; pl. 15, figs 62-66. 1995 Placenticeras maherndli Summesberger; Kennedy in Ken- 3. Repositories of specimens nedy et al., p. 411, pl. 22, fig. 7. NHMW Natural History Museum, Vienna, Austria GBA Geologische Bundesanstalt (Geological Survey of Type: the holotype, by original designation, is MA 77/ 2, form Austria, former k. k. Geologische Reichsanstalt), Vien- A, the original of Summesberger, 1979 (pl. 14, fig. 58, 59).___ na, Austria Material: SK/HO/1995/7, SK/HO/1989/6, NHMW/2016/0191/0001 MA Wolf-Peter Maherndl collection, Bad Ischl, Austria Description: SK/HO/1995/7 (Fig. 7/4, 5), SK/HO/1989/6 and SK Dr. Peter Skoumal collection, Vienna, Austria NHMW/2016/0191/0001 are fragments of internal moulds GPIT Geologisch Paläontologisches Institut der Universi- with large areas of the original shell preserved. NHMW/2016/ tät Tübingen_______________________________ 0191/0001 is heavily crushed. SK/HO/ 1995/7 is the best pre- LPMP Laboratoire du Muséum de Paléontologie, Paris served individual. All three specimens are deformed into an ellipse. Measurements (Tab. 2) are restored._____________ 4. Systematic Palaeontology Class Cephalopoda Cuvier, 1797 D Wh Wb U U% Order Ammonoidea Zittel, 1884 rest rest SK/HO/1995/7 60 30 14.4 15 25% Suborder Ammonitina Hyatt, 1889 rest rest rest NHMW/2016/0191/1 60 30 -- 15 25% Superfamily Desmoceratoidea Zittel, 1895 rest rest rest Table 2: Measurement of Placenticeras aff. maherndli Summesberger, Family Pachydiscidae Spath, 1922 1979 from the Hofergraben site. Deformed dimensions are restored (rest). Pachydiscus sp. indet., juv. Fig. 6/5; Tab. 1 SK/HO/1995/7 and NHMW/2016/0191/0001 are apparently Description: SK/HO/1996/8 (Fig. 6/5) is a small internal mould adult individuals with the body chamber preserved. They are with large areas of adherent shell preserved. Coiling is involute, laterally flattened to a certain degree. Coiling is moderately the specimen deformed into an ellipse by compaction.The involute, the umbilicus comprising about 25% of the diame- expansion rate is high. Close to the adapertural end the whorl ter. The umbilical depth increases through ontogeny. The section is almost circular. The umbilicus is deep and narrow, umbilical wall is steep and outwards inclined, the umbilical the umbilical shoulder rounded. About ten irregular coarse shoulder narrowly rounded. SK/HO/1989/6 is a fragment of ribs arise on the umbilical shoulder in the form of elongated an umbilicus, with clearly visible umbilical tubercles; these bullae, some of which cross the flank and extend over the are less distinct in SK/HO/1995/7. This specimen shows cla- venter, others end around mid-flank. There are no constric- vate ventrolateral tubercles close to the ventrolateral edge. tions or ventral tubercles; the sutures are not visible._______ The flanks are slightly convex, the venter concave between Discussion: The specimen is interpreted as a juvenile pachydis- ventrolateral ridges. The flanks are covered with very fine fal- cid, which we are unable to link to adult specimens of the same coid lirae, increasing in strength towards the aperture. They age. It is not a microconch, as it lacks ventrolateral tubercles._ are prorsiradiate at the umbilical shoulder, sweeping over the Occurrence: Known only from the Hofergraben (Gosau, Upper flank in a wide convexity before finally flexing back towards Austria). the ventrolateral edge in a prorsiradiate concavity. SK/HO/ 1995/7 shows partially visible, crowded sutures.___________ Discussion: Placenticeras aff. maherndli differs from Placenti- DDrest Wh Wb U U% ceras maherndli Summesberger, 1979 in its fine lirate ribbing