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Xenosphinctes n. gen. (Ataxioceratidae, Lithacoceratinae), a new rare ammonite genus from the Lower Tithonian (Hybonotum Zone) of SW Germany

Scherzinger A., Schweigert G.

Volumina Jurassica

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2017

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Vol. 15, no 1

155--160

EN

The new monotypic ammonite genus Xenosphinctes (type species: Xenosphinctes berkai n. sp.) is established. It is recorded from the Upper Jurassic, Early Tithonian, Hybonotum Zone, Riedense Subzone, eigeltingense α horizon from the Talmühle, N of Engen, Baden-Württemberg, SW Germany.

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Comments on the identification of Ammonites planula Hehl in Zieten, 1830 (Upper Jurassic, SW Germany)

Schweigert G., Kuschel H.

Volumina Jurassica

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2017

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Vol. 15, no 1

1--16

EN

Ammonites planula Hehl in Zieten, 1830 is the type species of the Late Jurassic ammonite genus Subnebrodites Spath, 1925 and the index species of the well-established Planula Zone of the Submediterranean Province. Recently, Enay and Howarth (2017) classified this stratigraphically important ammonite species as a ʻnomen dubiumʼ and considered it to be the possible macroconch counterpart of Idoceras balderum (Oppel, 1863). These authors claimed “Subnebrodites planula Spath, 1925” instead of Ammonites planula (Hehl in Zieten, 1830) to be the type species of Subnebrodites. However, their nomenclatorial acts are based on erroneous assumptions. For future taxonomic stability we here propose a neotype for Ammonites planula (Hehl in Zieten, 1830) and a lectotype for Ammonites planula gigas Quenstedt, 1888. In addition, dimorphism within the stratigraphically much younger Idoceras balderum (Oppel) is demonstrated showing that there is no morphological resemblance and no closer relationship with Ammonites planula (Hehl in Zieten, 1830).

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Additional Tithonian and Berriasian ammonites from the Vaca Muerta Formation in Pampa Tril, Neuquén Basin, Argentina

Parent H., Schweigert G., Scherzinger A., Garrido A. C.

Volumina Jurassica

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2017

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Vol. 15, no 1

139--154

EN

The ammonite fauna of the Tithonian–Berriasian of the Vaca Muerta Formation in Pampa Tril has been recently described in detail. New important specimens and additional information are presented in this paper. The phyletic evolution of Choicensisphinctes, passing from C. platyconus to C. erinoides is confirmed, as well as the sexual dimorphic correspondence of this latter with C. mendozanus. A microconch of the genus Krantziceras is described for the first time. New specimens of Substeueroceras koeneni identical to the paralec¬totype, along with material already described from the koeneni Hz. (Koeneni Zone), point to the fixation of this horizon as the type horizon of the species. New specimens of Subthurmannia boissieri from the Damesi Zone match clearly the range of variation of this species in Spain, thus providing an element for time-correlation with the Tethyan standard scale. Additional material from the internispinosum alpha Hz. confirms the origin of W. internispinosum from C. proximus by the inception of an evolutionary innovation in the juvenile ontogeny.

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Towards a consistent Oxfordian/Kimmeridgian global boundary: current state of knowledge

Wierzbowski A., Atrops F., Grabowski J., Hounslow M., Matyja B. A., Olóriz F., Page K., Parent H., Rogov M. A., Schweigert G., Villaseñor A. B., Wierzbowski H., Wright J. K.

Volumina Jurassica

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2016

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Vol. 14, no. 1

15--49

EN

New data are presented in relation to the worldwide definition of the Oxfordian/Kimmeridgian boundary, i.e. the base of the Kimmeridgian Stage. This data, mostly acquired in the past decade, supports the 2006 proposal to make the uniform boundary of the stages in the Flodigarry section at Staffin Bay on the Isle of Skye, northern Scotland. This boundary is based on the Subboreal-Boreal ammonite successions, and it is distinguished by the Pictonia flodigarriensis horizon at the base of the Subboreal Baylei Zone, and which corresponds precisely to the base of the Boreal Bauhini Zone. The boundary lies in the 0.16 m interval (1.24–1.08 m) below bed 36 in sections F6 at Flodigarry and it is thus proposed as the GSSP for the Oxfordian/ Kimmeridgian boundary. This boundary is recognized also by other stratigraphical data – palaeontological, geochemical and palaeomagnetic (including its well documented position close to the boundary between magnetozones F3n, and F3r which is placed in the 0.20 m interval – 1.28 m to 1.48 m below bed 36 – the latter corresponding to marine magnetic anomaly M26r). The boundary is clearly recognizable also in other sections of the Subboreal and Boreal areas discussed in the study, including southern England, Pomerania and the Peri-Baltic Syneclise, Russian Platform, Northern Central Siberia, Franz-Josef Land, Barents Sea and Norwegian Sea. It can be recognized also in the Submediterranean-Mediterranean areas of Europe and Asia where it correlates with the boundary between the Hypselum and the Bimmamatum ammonite zones. The changes in ammonite faunas at the boundary of these ammonite zones – mostly of ammonites of the families Aspidoceratidae and Oppeliidae – also enables the recognition of the boundary in the Tethyan and Indo-Pacific areas – such as the central part of the Americas (Cuba, Mexico), southern America, and southern parts of Asia. The climatic and environmental changes near to the Oxfordian/Kimmeridgian boundary discussed in the study relate mostly to the European areas. They show that very unstable environments at the end of the Oxfordian were subsequently replaced by more stable conditions representing a generally warming trend during the earliest Kimmeridgian. The definition of the boundary between the Oxfordian and Kimmeridgian as given in this study results in its wide correlation potential and means that it can be recognized in the different marine successions of the World.

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First record of the Mediterranean zonal index Mesosimoceras cavouri (Gemmellaro, 1872) in the Upper Jurassic (Pseudomutabilis Zone, semicostatum γ horizon) of SW Germany and its stratigraphical significance

Scherzinger A., Schweigert G., Főzy I.

Volumina Jurassica

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2016

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Vol. 14, no. 1

145--154

EN

The ammonite species Mesosimoceras cavouri (Gemmellaro), the index of the Mediterranean Cavouri Zone, is recorded for the first time from the Submediterranean Upper Jurassic of SW Germany. It occurs in the Untere-Felsenkalke Formation, within a rich ammonite association of the late Pseudomutabilis Zone characterized by fine-ribbed variants of Aulacostephanus pseudomutabilis (de Loriol) and a still undescribed flexuous-ribbed variant of Aulacostephanus eudoxus (d’Orbigny). This ammonite association represents the here newly introduced Lingulaticeras semicostatum γ horizon. The record of Mesosimoceras cavouri (Gemmellaro) confirms at least a partial correlation of the Mediterranean Cavouri Zone with the Submediterranen Pseudomutabilis Zone and the Subboreal Eudoxus Zone.

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Ecdysichnia : a new ethological category for trace fossils produced by moulting

Vallon L. H., Schweigert G., Bromley R. G., Röper M., Ebert M.

Annales Societatis Geologorum Poloniae

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2015

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Vol. 85, No. 3

433--444

EN

The shedding of exoskeletons is an important aspect of the lifecycle of some in vertebrates (mainly arthropods). To rid them selves of the old cuticula (= exuvia), these animals of ten have to thrash about, twist around or rub themselves against the sediment or other more or less solid objects. In softgrounds, this behaviour may create distinctive patterns that have to be regarded as trace fossils. Accordingly, some ichnospecies of Rusophycus have recently been interpreted as traces made during ecdysis. Most of the so-called “Schwoimarken” from the Solnhofen lithographic limestones (Upper Jurassic, SE Germany), usually interpreted as structures made by dead organisms swaying in response to water movements, must be understood as traces of arthropod ecdysis. In this context, we erect Harpichnus bartheli igen. et isp. nov. and propose the new ethological category, ecdysichnia, for moulting traces. In most “Schwoimarken” containing body-fossil remains other than arthropods, we see sediment displacement by scavenging arthropods rather than mortichnia (sensu Seilacher, 2007). We further propose inclusion of the recently erected category pupichnia for pupation chambers as a subcategory of ecdysichnia. In our opinion, pupation is a special form of moulting that does not justify the splitting of categories, as briefly noted by Vallon et al. (2013).

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The base of the Tithonian Stage – historical review and state of the art

Schweigert G., Atropos F.

Volumina Jurassica

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2006

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Vol. 4, no. 1

213-214

EN

When introducing the Tithonian Stage in a preliminary way, Oppel in 1865 listed several localities, which, according to him, yielded typical faunas of this age. The original list of Oppel comprises 117 taxa, mostly ammonites. The main localities which proliferated these taxa are: Rogoenik, Radzichov (Polish Carpathians), Ignaziberg, Koniakow, Willamowice, TeĘin (Silesia), Stramberk (Moravia), Trento, Rovereto (Southern Alps), Ruhpolding (Eastern Alps), Solnhofen, Eichstatt, Neuburg a. d. Donau (Bavaria), Nusplingen (Swabia), Grenoble, Val d'Ormonds (Switzerland), Chambery (Savoie), Boulogne-sur-Mer (Normandy), and Portland (Dorset). However, no type locality was ever selected. One of the localities in Oppel's list, Nusplingen, is not a time equivalent of the Solnhofen Limestones in Franconia, as suggested by Oppel in disregard of the completely different ammonite faunas. In the original definition of the Tithonian no zonal subdivision was presented. The first ammonite zone of the Tithonian, the Hybonotum Zone, was informally proposed by Benecke (1866, "Schichten des Ammonites hybonotus and lithographicus"), who focussed on the correlation between the Tithonian in the Tethyan Late Jurassic - mainly the Ammonitico Rosso Superiore of the Southern Alps - and its supposed coeval deposits in SW Germany. This Hybonotum Zone was an assemblage range zone, which included the taxa from the Diphyakalk of the Southern Alps, intercalated between the beds containing Aspidoceras acanthicum and the Early Cretaceaous Biancone, thus being approximately synonymous with the Tithonian Stage of Oppel. Neumayr introduced the Beckeri Zone in 1873 by subdividing the Acanthicum Zone. An increase of provincialism in the Late Jurassic forced the establishment of several independent zonal schemes and stages. Today, the Tithonian Stage starting with the Hybonotum Zone is regarded as standard for chronostratigraphy in the Jurassic. More recently several attempts for a definition of the Kimmeridgian/Tithonian boundary, the base of the Hybonotum Zone, were made. Sections in SW Germany were studied in detail but it was not possible to find suitable sites for the proposal of a GSSP. The only published suggestion is from Contrada Fornazzo near Castellammare in W Sicily, but the flatter section is rather poor in respect of its ammonite faunas and hence of little correlation value, especially in contrast to sections in SE France (Canjuers, Mt. Crussol). The latter provide rich, well-preserved faunas with a succession of chronospecies of Hybonoticeras (in ascending order): Hybonoticeras kamicense (Schopen) - H. n. sp. - H. pseudohybonotum Vigh - H. n. sp. (=autharis sensu Berckhemer & Holder) - H. hybonotum (Oppel) - H. n. sp. They are accompanied by numerous perisphinctids, oppeliids and aspidoceratids. The final decision of a GSSP for the base of the Tithonian Stage is a formal convention, in which these valuable data should be taken into account, and we warn of a premature decision

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New studies on perisphinctids from the Lower Tithonian (Hybonotum Zone) of S Germany and SE France

Scherzinger A., Atrops F., Schweigert G.

Volumina Jurassica

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2006

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Vol. 4, no. 1

244-245

EN

New extensive collections from the Hybonotum Zone of Liptingen (SW Germany), Canjuers (Dpt. Var, France) and Crussol (Dpt. Ardeche, France), together with already published material from Laisacker (Franconia, S Germany, Schairer & Barthel 1981) give deep insights in ontogeny, intraspecific variation, dimorphism, and evolution of several Late Jurassic perisphinctid ammonite genera, as a basis for future revisions. In older studies perisphinctids were often problematic due to little material, erroneous interpretations of type species, incompletely or poorly preserved specimens, disregarding of dimorphism, and widespread homeomorphism. After our recent study the perisphinctids are much more diverse than previously thought. A correlation with French biohorizons established in the Paris and Aquitaine basins is possible due to the occurrence of Gravesia M+m and Tolvericeras M+m?, especially at Liptingen. Besides the two latter genera we can distinguish five other dimorphic pairs which are coupled as follows: Lithacoceras Hyatt (M) + Silicisphinctes Schweigert & Zeiss (m); group of "Virgatosphinctes" eystettensis Schneid (M) + Subplanites group A (m); Euvirgalithacoceras Zeiss, Schweigert & Scherzinger (M) + Subplanites group B, S. rueppellianus sensu Schairer & Barthel non Quenstedt (m); Hegovisphinctes Zeiss, Schweigert & Scherzinger (M) + group of "Torquatisphinctes" filiplex Schairer & Barthel non Quenstedt (m); Hoelderia Ohmert & Zeiss (M) + group of "Subdichotomoceras" sp. in Schairer & Barthel 1981, pl. 5, fig. 4 only (m). Some of these dimorphic pairs can be recognized also in SE Spain (Calanda area) and in the Balkans (Bulgaria, Croatia) and thus permit correlations across the Submediterranean Province. The rich perisphinctid fauna, together with other excellently preserved ammonites underlines the potential of the French sections as key sections for long-distance and high time-resolution correlations as well as the understanding of the Kimmeridgian-Tithonian transition.