Volumina Jurassica

Suevisphinctes – a new perisphinctid ammonite genus from the Lower Tithonian (Hybonotum Zone) of Southern Germany

2024-09-03T08:11:08+02:00

A new Upper Jurassic perisphinctid ammonite genus, Suevisphinctes (type species: Suevisphinctes josefkelleri nov. gen., nov. sp.), is established. At present, it is recorded from the laisackerensis biohorizon (Early Tithonian, Hybonotum Zone, Rueppellianus Subzone) of SW Germany. A historical ammonite specimen of supposed Tithonian age from the Polish Klippen of Iskrzyczyn may be assigned to Suevisphinctes as well and thus indicates a possible Tethyan origin of this enigmatic genus.

News and Reviews – Axel von Hillebrandt (1933–2024)

2024-07-03T12:21:01+02:00

The first records of Pictonautilus Branger, 2004 (Cephalopoda: Nautiloidea) from the Upper Bathonian – ? Lower Callovian (Middle Jurassic) of Germany and Poland

2024-07-02T07:17:04+02:00

The rare Middle Jurassic nautilid genus Pictonautilus Branger, 2004 is reported for the first time from Upper Bathonian strata of SW Germany and from Upper Bathonian – ? Lower Callovian beds of S Poland. The new specimens can be assigned to the type species P. verciacensis (Lissajous, 1923) and point to a larger maximum size than previously expected. Although the new findings expand the geographic range of this genus, its phyletic origin remains unknown. From its original description and illustration, Nautilus (Paracenoceras) wilmae Jeannet, 1951, from the Lower Callovian of Switzerland, was suspected to represent another species of Pictonautilus. After study of the holotype, however, this taxon is considered a junior subjective synonym of “Paracenoceras” calloviense (Oppel, 1857). Another specimen from the Lower Callovian of SW Germany cited as Nautilus (Paracenoceras) wilmae Jeannet, 1951 was misidentified and represents the first hitherto recognized record of the dwarfish Paracenoceras dorsoexcavatum (Parona, Bonarelli, 1895) from Europe besides the holotype from Savoy.

Summary of a decade of research at the Owadów–Brzezinki Lagerstätte (Tithonian, central Poland): A review and perspectives for the future

2024-03-21T12:00:22+01:00

For over ten years, the Lower to Upper Tithonian boundary beds cropping out in the Owadów–Brzezinki quarry have yielded numerous fossils of ammonites, bivalves, brachiopods, xiphosurans, decapods, insects, and vertebrates – including actinopterygian fishes and various reptiles and others, all of which exhibit fine preservation of their anatomical details due to special environmental conditions during their fossilization. The Owadów–Brzezinki section is also important for stratigraphical correlations because it contains ammonite faunas indicative of the NE European and NW European Subboreal zonal schemes, as well as Tethyan calpionellids. The whole faunal assemblage, which represents taxa of many iconic groups of Mesozoic animals, has created the opportunity to establish the ‘Owadów–Brzezinki geopark’, a geoeducation area where the public, and especially the young, can learn about the beauty of the natural history of the region.

Development and chronology of the Late Jurassic shallow-water carbonate deposits of the Holy Cross Mountains area, central Poland

2024-03-05T11:21:19+01:00

The Late Jurassic shallow-water carbonates with intervening clayey-marly deeper-water deposits in the Holy Cross Mts. area formed over large bank of the elevated part of the Northern Tethyan Shelf during about 12 myr. They comprise three main successions (I, II and III) deposited partly in different environmental conditions, controlled by tectonic and climatic factors, and still preserved in the north-eastern margin, the north-western margin and the south-western margin of the Holy Cross Mountains. The history of sedimentation is presented according to the concept of the large tectono-stratigraphic units COK, LUK and KVB, which owe their origin to variable rates of tectonic subsidence, as introduced by Kutek (1994) for the area of central Poland. The studied deposits of the COK megasequence corresponding to the Upper Oxfordian and the Lower Kimmeridgian up to the Hypselocyclum Zone consist of coral limestones, various grained (including oolitic) limestones, and micritic limestones formed over the gradually enlarging shallow-water carbonate platform of the Holy Cross Mts. This platform was subsequently subdivided into two elevated areas, separated by a depressed zone in the middle, bounded by the Nowe Miasto–Iłża–Bałtów Fault Zone in the north-east and the Holy Cross Fault System in the south. The younger megasequence LUK with it strongly transgressive character marks the successive stages of the marine transgression which entered the central, lowered part of the area of the Holy Cross Mts. from the west, where it appeared already in the early Hypselocyclum Chron. It successively spread across the Holy Cross Mts. area towards the north-east and south bringing everywhere the deposition of various oyster lumachelles and marls with ammonites at the end of the Hypselocyclum Chron and during the Divisum Chron of the Early Kimmeridgian to the Acanthicum/Mutabilis Chron of the earliest Late Kimmeridgian. The following megasequence KVB is represented by the detrital lumachelles and chalky limestones with nereineids of the Eudoxus Chron of the Late Kimmeridgian marking the development of still younger shallow-water carbonate platform in the uplifted areas in the north-eastern and possibly the south-western margins of the mountains, allegedly subdivided by a deeper area of sedimentation of marly deposits. The youngest Late Jurassic deposits of the Holy Cross Mts., are very fragmentarily preserved, mostly because of Early Cretaceous uplift and erosion. They suggest an initial episode of complete drowning of the carbonate platform which became covered by marly deposits during the Early Tithonian, and the subsequent restoration of shallow-water carbonate sedimentation at the end of the Early Tithonian.

Corbinites (Subfamily Lithacoceratinae), a new genus for the giant western Canadian Late Kimmeridgian or Tithonian (Late Jurassic) ammonite Titanites occidentalis Frebold

2024-02-19T09:07:58+01:00

The finding of two new specimens and a reappraisal of the single original specimen of the problematic giant Canadian Late Jurassic ammonite Titanites occidentalis Frebold results in the creation of Corbinites, n. gen. It is assigned to the ataxioceratid subfamily Lithacoceratinae largely because of the presence of variocostate and previously unrecognized ataxioceratoid ribbing in middle and late growth stages. With enigmatic ancestry and geographically removed other forms with similar characteristics, the species may have been endemic in the relatively isolated early Alberta foreland basin of western interior Canada.

A new species of Pseudhimalayites (Ammonitina, Aspidoceratoidea) from the Lower Tithonian of the Betic Range, Southern Spain

2023-10-04T15:23:01+02:00

The Late Jurassic aspidoceratoid genus Pseudhimalayites Spath is scarcely recorded but widely distributed in the Andean basins, the Caribbean region, and in the European Tethys. From Ponti Zone (Lower Tithonian) rocks of the Betic Range in Carchelejo we describe here the new species Pseudhimalayites carchelejensis, based on a macroconch (female) holotype. The corresponding microconch (male), described from the same ammonite assemblage, would belong to the morphogenus Simocosmoceras Spath which groups the microconchs of Pseudhimalayites. P. carchelejensis n. sp. differs from the coeval Pseudhimalayites steinmanni (Haupt) by lacking ventral tubercles in the phragmocone and by bearing umbilical tubercles only from the adult whorl of the phragmocone. These differences illustrate a significant morphologic divergence between the Andean and the Tethyan lineages.

Revised holostratigraphy of the Tithonian-Berriasian transition at Tré Maroua (Le Saix, Hautes-Alpes, SE France): Study of a rejected Berriasian GSSP candidate

2023-06-28T10:51:49+02:00

The study of the Tithonian and lower Berriasian succession of Le Saix (Hautes-Alpes, France) has made it possible to better characterize the lithological succession at a former Berriasian GSSP candidate, its set of microfacies, the stratigraphic ranges of the main groups of marine plankton and therefore the calpionellid and saccocomid biozonations. On the lithological level, the Tithonian strata are characterized by thick-bedded breccias representing debris flows and related calciturbidites, whereas the Berriasian strata are typically white limestones. The lower part of the Berriasian is comprised of scattered intercalations of thin-bedded breccias and calciturbitides (including cryptic mud calciturbidites). In thin sections, the white limestones display mud- to wackestone textures and their allochems are mostly tiny bioclasts (e.g., radiolarians, calpionellids, saccocomids). Calciturbidites have wacke- to grainstone textures and their allochems are mostly pseudointraclasts and extraclasts, comprising various bioclasts and some ooids. Mud turbidites are made of micrograinstones some yielding almost exclusively well-sorted calpionellids, which were previously erroneously interpreted as the signature of “explosions” or “blooms” of Calpionella alpina. Breccias are mostly lithoclastic floatstones with a matrix similar to that of the calciturbidites. Their lithoclasts are either extraclasts sensu stricto, i.e., material derived from updip shallow-water areas, or pseudointraclasts representing reworked subautochthonous material, i.e., mud- and wackestone lithoclasts with radiolarians, saccocomids and/or calpionellids. Radiolarians are common over the whole studied interval. Saccocomids are part of the dominating biota reported from the lower and lower upper Tithonian interval whereas calpionellids replace them in the uppermost Tithonian to lower Berriasian interval. Minor planktonic groups comprise calcareous dinoflagellates and Globochaete alpina; Iranopsis nov. group is also present. Intervals with saccocomid sections characteristic of zones 4–5 and zone 6 are respectively ascribed here to the lower Tithonian (4–5) and the lower upper Tithonian (6). The biozonation of the calpionellid group sensu lato allows identification of i) the Boneti Subzone of the chitinoidellids, ii) the Crassicollaria Zone, more specifically its Tintinnopsella-Intermedia (A1), Intermedia-Alpina (A2) and Brevis-Massutiniana (A3) subzones, and iii) the Alpina Zone, with its Alpina-Parvula (B1) and its Alpina-Remaniella (B2) subzones. On the basis of biostratigraphical and sedimentological data, most zonal boundaries prove to be hiatal, located at the erosional base of breccia or turbidite layers whereas the Tithonian/Berriasian stage boundary appears to be located at a strike-slip fault plane in the Tré Maroua section.

News and Reviews – Jurassica XV, 19–22 September 2023 Iłża, Poland. First circular

2023-01-09T13:07:59+01:00

Phylogeny of the ammonite family Aulacostephanidae Spath, 1924 during the Late Oxfordian and the Early Kimmeridgian in Europe: Main lineages, patterns of evolution and sedimentological to palaeogeographical controls on evolutionary development

2022-10-25T08:06:38+02:00

The evolutionary history of the Aulacostephanidae presented here includes the interval of about 5 Ma of the Late Oxfordian and Early Kimmeridgian ranging from the origin of the family to is maximal development. The development and biogeographical distribution of aulacostephanids in Europe were related mostly to sea-level changes and tectonics. The appearance of the ancestor genus Decipia and the following genus Ringsteadia was controlled by marine transgressions during the Late Oxfordian which stimulated also the distribution of these ammonites in Subboreal and Submediterranean Europe. The main faunal turnover at the Oxfordian/Kimmeridgian boundary was related to allopatric speciation correlated to separation of the aulacostephanid assemblages: it resulted in the appearance of the main Ringsteadia–Pictonia–Rasenia lineage in NW Subboreal Europe and the side-lineages Ringsteadia–Vielunia–Eurasenia/Involuticeras and Ringsteadia–Vineta–Balticeras–Rasenioides in NE Subboreal and Central Submediterranean Europe. A strong development of the shallow-water carbonate platforms during the Early Kimmeridgian stimulated the development of still another Pictonia (Pomerania) – Rasenia (Pachypictonia) lineage. The main faunal turnover correlated to a large transgression at the end of the Early Kimmeridgian resulted in the sudden distribution of the new aulacostephanid faunas over large areas of northern and central Europe, and opened a new stage in the evolutionary development of the family.