Ammonite Fauna Research Articles

Itierella melognensis n.gen., n.sp., and Paradicostella hautevillelompnesensis n.gen., n.sp. (Ammonoidea, Neocomitidae, Neocomitinae), two new upper Valanginian trituberculated ammonoids from the Jura Mountains, eastern France

Several ammonoid specimens from the upper Valanginian (Lower Cretaceous) sedimentary succession of Hauteville-Lompnes, Department of Ain, eastern France, are assigned to the new genera and species Itierella melognensis n.gen., n.sp., and Paradicostella hautevillelompnesensis n.gen., n.sp. Specimens collected in the past were misidentified as Acanthodiscus Uhlig, 1905, and erroneously assigned to the lowermost part of the Hauterivian stage. The revision of the Marnes de Mélogne, along with the collection of a rich associated ammonite fauna, allows Itierella to be recognized as a latest Valanginian homeomorphic form of the genus Acanthodiscus, and Paradicostella as closely related to the genus Dicostella Busnardo, 1966. The Marnes de Mélogne are revised as mostly belonging to the upper Saynoceras verrucosum to Criosarasinella furcillata ammonite zones (uppermost Valanginian), while their uppermost metre is assigned to the Acanthodiscus radiatus Zone (lowermost Hauterivian).

Pelsonian and Illyrian (Anisian, Middle Triassic) ammonoid faunas from the Bulog Group of Kovčezi, Durmitor Mountain, Dinarides (northern Montenegro)

Pelsonian and Illyrian (Anisian, Middle Triassic) ammonoid faunas from the Bulog Group of Kovčezi, Durmitor Mountain, Dinarides (northern Montenegro)

Biochronostratigraphy and palaeobiogeography of Echioceratidae (Ammonitina) from the Raricostatum Zone (Aplanatum Subzone) in NW Iberia

This paper examines the uppermost Sinemurian and lowermost Pliensbachian ammonite fauna recorded in NW Iberia with a special focus on Echioceratidae from the Aplanatum Subzone. In total, 852 specimens have been collected bed-by-bed from five reference sections from the Asturian, Basque-Cantabrian, and Lusitanian basins. Echioceratidae, namely Paltechioceras genus, represent 86.2% of the sample, Polymorphitidae (Leptonotoceras genus) the 10%, and less than 4% of the specimens are Eoderoceratidae, Phricodoceratidae, or Oxynoticeratidae. This study describes five species of Paltechioceras, namely P. tardecrescens, P. oosteri, P. recticostatum, P. elicitum, and P. romanicum. They allow a biochronostratigraphic division for the studied basins and its worldwide correlation. One of the species, P. romanicum, is the latest one registered in all the studied sections, occurring directly below the Sinemurian–Pliensbachian boundary. The disappearance of this widely distributed species marks the echioceratids extinction. This work reviews the global events described around the Sinemurian–Pliensbachian transition (the Sinemurian–Pliensbachian boundary event). Finally, we present a palaeobiogeographical analysis of the Paltechioceras species described, giving more information to discuss the opening of the Hispanic Corridor during the late Sinemurian.

An Uppermost Famennian section with ammonoids in Karaganda Region, Central Kazakhstan

The Sherubay-Nura section is located in the Karaganda Coal Basin, paleogeographically accretionary complexes of Kazakhstania, a Middle Paleozoic terrane that was colliding with Siberia during the Late Devonian. Rich ammonoid faunas have been discovered in this and other outcrops of the region during Sovietera geological mapping. We present the first field reassessment of the section since the 1980s, elucidating previously unknown deep-water character, gamma-spectrometry response, position of ammonoid limestones in the facies succession, and thermal overprint due to basalt dike intrusions and hydrothermal flushing.

The ammonite faunas of the upper Hypselocyclum to Divisum zones (Lower Kimmeridgian, Upper Jurassic) at Małogoszcz, Holy Cross Mts., central Poland: their stratigraphical interpretation and evolutionary development

The transgressive succession of deposits of the upper Lower Kimmeridgian at Małogoszcz in the south-western margin of the Holy Cross Mts. in central Poland yielded diversified faunas of ammonites. The commonly represented Submediterranean ataxioceratid ammonites include the last members of Ataxioceras in the Hypselocyclum Zone and the assemblage of various Crussoliceras, Garnierisphinctes and Progeronia, mostly developed in the Divisum Zone, and associated upwards (Uhlandi Subzone) with aspidoceratids (Pseudhimalayites). A few typical Mediterranean ammonites (Nebrodites, Presimoceras, Idoceras, Taramelliceras) are indicative of the Herbichi Zone. The Subboreal ammonites include mostly Eurasenia and Involuticeras in addition to some Rasenia and Rasenioides of the uppermost Cymodoce Zone, corresponding to the Askepta Subzone. The changes in composition of ammonite faunas and comparison with the coeval faunas of other areas of Europe give indications on the evolutionary development of some Ataxioceratidae and Aulacostephanidae at the end of Early Kimmeridgian. The development of the Crussoliceras, Garnierisphinctes and Progeronia, having possibly their roots in the Mediterranean areas, was strictly correlated with the overall transgression and oscillations of sea-level controlled possibly by climatic eccentricity cycles of the northern Tethyan shelf. This resulted also in the decline of older Ataxioceras and its nearby allies. The indigenous lineage of Aulacostephanidae includes the transition from Eurasenia to “Pararasenia”. The development from Rasenioides to Aulacostephanoides occurred mostly in the Subboreal areas – although some late representatives of Rasenioides like R. moeschi reached the area of study. The existence of an independent lineage leading from Rasenia involuta to heavily-ribbed Aulacostephanoides/Aulacostephanus is also suggested.

Ammonites from the Late Jurassic (Oxfordian- early Kimmeridgian) of central-eastern Mexico and their paleobiogeographic relationship with Cuba, Chile, and Argentina

Three bearing mid-late Oxfordian and early Kimmeridgian ammonite stratigraphic sections, corresponding to the Santiago Formation, located in the surroundings of Tamán (San Luis Potosí), Tenango, and La Mesa-El Pescado (both in Hidalgo) towns were studied. The presence of the genera Passendorferia, Neumannia, Sequeirosia (Gemmellarites), Perisphinctes (Otosphinctes), and Gregoryceras support the existence of an extensive communication via with the Tethys during the Plicatilis-Transverarium Chrons. On the other hand, for the Bifurcatus Chron, fauna with Tethys affinity is still recognized, including the genera Neoprionoceras, Subdiscosphinctes, Ochetoceras, and Euaspidoceras. In addition, is possible to establish a paleobiogeographic affinity with Cuba, Chile, and Argentina based on the occurrence of Vinalesphinctes, Perisphinctes (Cubasphinctes), and Caracoliceras, which is also supported by the presence of Physodoceras and Subnebrodites in the Hypselum/Bimammatum Chrons. Finally, the record of Passendorferia, Ochetoceras, and Euaspidoceras throughout the entire stratigraphic succession confirms that the connection with the Tethys was present throughout the Oxfordian and early Kimmeridgian. Based on these paleogeographic interpretations, the Tethys influence on the Oxfordian-Kimmeridgian Mexican ammonite faunas is confirmed. For areas currently integrated into Cuba, the record in Mexico of forms with Cuban affinity reveals the existence of a paleobiogeographic entity in the northern margin of the western portion of the Hispanic Corridor; while the faunal affinity with Chile and Argentina is interpreted as evidence of a connection with these epicontinental areas, which favors dispersal by marine currents.

Taxonomic and paleobiogeographic review of the Guadalupian ammonoids reported by González-Arreola et al. (1994) from the Olinalá Formation, Guerrero state, Mexico

A review of twenty-five ammonoid specimens of the Guadalupian age from the Olinalá Formation, Guerrero state, as recorded by González-Arreola et al. (1994) is presented as part of a study of middle Permian ammonoid faunas from Mexico. The present update includes new images of González-Arreola's ammonoids. Six taxa have been identified to species level and one species in open nomenclature. Three taxa recognized by González-Arreola et al. have been revised and reassigned to other genera, two species-level identifications have been changed, and a species previously not reported is for the first time described from the original designation. The ammonoid faunal composition suggests that the base to the middle part of the Olinalá Formation is correlated to the Wordian (middle Guadalupian). Reference to published paleobiogeographic data has suggested that the present ammonoid specimens be assigned to the American Realm and indicates a clear affinity with contemporaneous ammonoid assemblages from the Paleothetys Realm.

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

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 as-semblage, 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.

Ammonites and stratigraphic succession of the middle Toarcian – lowermost Aalenian from the Jebel Amergou (Moulay Bouchta area, Internal Prerif Zone, External Rif belt, northern Morocco)

In the Rif Belt, the Toarcian–Aalenian outcrops are rare. The most important of these outcrops are those of the northern side of Jebel Amergou (70 km northwest of Fez). These outcrops, consisting of lumpy marlstones and marly limestones, are rich in ammonites. A section (JAM) located in a small ravine near Douar Amergou have been studied. Its stratigraphic series (20 m-thick), called the Amergou Formation, is divided into two members. The lower member yielded in the levels 3 and 4 a rich ammonite fauna from the middle Toarcian (Bifrons and Gradata zones) and some ammonites from the upper Toarcian (Bonarellii and Speciosum? zones); the upper member, divide into two levels, yielded in the level 2 rare ammonites from the lower Aalenian (Opalinum Zone). 44 species of ammonites have been identified, described and illustrated for the first time from the Toarcian–lower Aalenian succession of the Rif Belt. Most of these species are common to several basins of both, the northern and the southern margins of the Tethys and the NW European province.

Late Cenomanian–early Turonian ammonite successions of north Eastern Desert, Egypt: biostratigraphy and paleobiogeographic implications

The upper Cenomanian-lower Turonian sequence of Egypt yield a remarkably diverse and plentiful ammonite fauna. Three stratigraphic sections located on Wadi Araba, north of the Southern Galal Plateau were investigated. Lithostratigraphically, the measured sections are subdivided from base to top into the Malha (pre-Cenomanian), Galala (Cenomanian) and Maghra El Hadida (Turonian) formations. Over a hundred well-preserved and nearly complete ammonite internal molds were collected. The studied ammonites are systematically classified as Vascoceratidae, Pseudotissotiidae, Acanthoceratidae and Engonoceratidae. Vascoceratidae and Pseudotissotiidae comprise 75% of the identified ammonites. Twelve ammonite species have been identified. Six late Cenomanian-early Turonian ammonite biozones are proposed herein: Neolobites vibrayeanus, Vascoceras gamai, Vascoceras cauvini, Vascoceras proprium, Choffaticeras segne, and Wrightoceras munieri. The identified ammonite biozones are correlated with NW European standard zonation and the Tethyan biostratigraphical schemes was performed. The first occurrences of Vascoceras proprium, as well as the first occurrences of the inoceramids Mytiloides kosmati and Mytiloides puebloensis define the Cenomanian-Turonian boundary. The diversity and abundance of studied fossil groups varied dramatically over the C/T transition. In the latest Cenomanian, all identified Cenomanian species had become extinct. Only three species have reached the Turonian time. The paleobiogeographic implications of the descried ammonites are thoroughly discussed. The paleogeographic distribution of the studied ammonite fauna shows that the majority of the described species are restricted to the shallow shelf of the southern Tethys.

Taxonomic review of Berriasian and Valanginian ammonites from Zacatecas State (north-central Mexico) studied by Burckhardt in 1906

A review of sixteen ammonoid specimens of the Berriasian and Valanginian age from Zacatecas, as recorded by Burckhardt in 1906, is presented as part of a larger-scale study of Valanginian ammonoid faunas from Mexico. The present update includes also museographic information and new images of Burckhardt's ammonites, as well as nine 3D models for better display of specimens. Six taxa have been identified to the species and two to generic level. In comparison to the original identifications of Burckhardt, four taxa have been transferred at the generic and four at the specific levels. Using stratigraphic range data from the literature, we assign the present ammonoid specimens to the uppermost upper Berriasian to lower Valanginian interval. The following biozones have been recognized: Tirnovella alpillensis, ‘Thurmanniceras’ pertransiens and Neocomites neocomiensiformis; with two subzones: ‘Thurmanniceras’ otopeta and Neocomites premolicus. Furthermore, a paleobiogeographic analysis of the taxa revised here indicates a clear affinity with contemporaneous ammonoid assemblages from the Mediterranean region.

Taxonomy, phylogeny and biostratigraphy of the upper Aptian–lower Albian ammonites of the Chott area, southern Central Tunisia

Four sections were measured and studied in the uppermost Aptian and lower Albian of the Chott Basin (southern Central Tunisia), providing an abundant, bed-by-bed collected paleontological material. The ammonite succession allows precise correlations with the ammonite biozonation established in Central Tunisia.The phylogeny of knemiceratids and acanthohoplitinids of the Chott Basin is investigated and the alleged extreme variability of knemiceratids is questioned.Five new ammonite species are herein described: Knemiceras sagetae sp. nov., Knemiceras lanceolatum sp. nov., Knemiceras multicostatum sp. nov., Knemiceras tunisiense sp. nov., Parengonoceras chottensis sp. nov., highlighting the highly endemic character of the Chott Basin ammonite faunas.

Ammonite biozonation and chronostratigraphy of the Upper Bajocian–Upper Oxfordian of the Dalichai Formation at the Kuh-e-Varvari section (North of Damghan, Alborz and North Iran)

ABSTRACT The Middle–Upper Jurassic strata in the eastern part of the Alborz, North of Iran (Dalichai Formation) were studied based on ammonite fauna to correlate with zonation of other West Tethyan areas (Sub-Mediterranean province). In this section, like other studied sections in North and northeast of Iran, the ammonite assemblages such as Parkinsoniidae, Morphoceratidae, Sphaeroceratidae, Macrocephalitidae and Reineckeiidae mainly show the characteristics of etyan groups. Abundant ammonite fauna in some levels has enabled an accurate chronostratigraphy. The presence of this ammonite fauna that is seen in the epicontinental seas, bordering the northern margins of the western Thetys, led to the identification of some zones in accordance with the standard of Sub-Mediterranean province zonation. The Garantiana and Parkinsoni Zones of the Late Bajocian, the Zigzag and Aurigerus Zones of the Early Bathonian, the Retrocostatum and Discus Zones of the Late Bathonian, the Bullatus and Gracilis Zones of the Early Callovian, the Anceps and Coronatum Zones of the Middle Callovian and the Athleta and Lamberti Zones of the Late Callovian have been recognised and characterised. These assemblages show a relation between these regions with the Sub-Mediterranean province during the Jurassic. Low percentage of Phylloceratidae in this section is an indicative of Sub-Mediterranean affinity. Based on the ammonite fauna, the Dalichai Formation is Late Bajocian-Late Oxfordian in age.

Taxonomic and stratigraphic remarks on Placites urlichsi Bizzarini, Pompeckjites layeri (Hauer), Carnites floridus (Wulfen) and Sageceras haidingeri (Hauer)

Investigations of an Lower Carnian Wettersteinkalk ammonoid fauna found in the Hochobir massif (Carinthia/Austria) gave rise to problems in the taxonomic relationship within the Triassic ammonoid Family Pinacoceratidae. The morphological parameters of the ammonoid genus Pompeckjites are rather unclear. Morphological variation of at least two ammonoid species as Pompeckjites layeri Hauer on one end, Placites urlichsi Bizzarini on the other end have to be take into account. Numerous field surveys, studies and excavations on upper Wettersteinkalk sites within the Karavank Mountains and Hallstatt-facies sites in the Northern Calcareous Alps were implemented and compared with the reference sites in the Dolomites. As a consequence of our investigations, the Hochobir Wettersteinkalk ammonite assemblage is thought to be equivalent in time to the ammonoid fauna of the Upper San Cassian Formation. The frequent occurrence of the Julian (Lower Carnian) ammonoid Placites urlichsi Bizzarini may be a powerful tool in field investigations for a refined correlation of the upper Wettersteinkalk reef limestone to the coeval basinal facies of the Upper San Cassian Formation (Lower Carnian/upper Trachyceras aonoides Zone). As a result of this study Placites urlichsi was included in the genus Pompeckjites. This paper could be an attempt to recognize the differences in juvenile forms of Pompeckjites layeri and Placites urlichsi and other similar disciform ammonoid genera like Carnites floridus and Sageceras sp. based on suture lines, polished transversal-sections and morphological features.

First record of Bochianites neocomiensis (Ancyloceratina, Bochianitidae) from the Valanginian of the Neuquén Basin, Argentina: Significance of the fauna and global correlation

A new Valanginian ammonoid fauna from the Vaca Muerta Formation in the Neuquén Basin is described and illustrated. It includes Bochianites neocomiensis (d’Orbigny), which is recorded for the first time in the lower Valanginian Lissonia riveroi Zone where it is associated with the Andean species L. riveroi (Lisson), and less commonly with Raimondiceras gerthi (Weaver) and Neocomites subtenuis Sayn. Above these levels, the Olcostephanus atherstoni and Karakaschiceras attenuatus subzones, comparatively poorly known in southern Mendoza, are recorded. Bioevents record the transition between CC3-B nannofossils Subzone of the lower Valanginian and the CC4-A nannofossils Subzone of the upper Valanginian. The finding of B. neocomiensis and N. subtenuis associated with endemic Andean faunas, and their calibration with calcareous nannofossils, allows establishing a much more accurate long-distance correlation between the Neuquén Basin and the West Mediterranean Province of the Tethys.

Chronostratigraphic overview of the Toarcian (Early Jurassic) ammonite fauna from the Mecsek Mountains (Hungary)

Chronostratigraphic overview of the Toarcian (Early Jurassic) ammonite fauna from the Mecsek Mountains (Hungary)

Lower Berriasian ammonites from Dedina (Golubac Mountains, eastern Serbia) and their biostratigraphic implication

A rich ammonite fauna was collected from the Dedina section, which is part of the Getic nappe system of the Serbian Dacia Megaunit. More than three hundred ammonites were collected from the light grey to reddish bioclastic limestones of the lower part and light grey marlstones of the upper part. From this fauna, 10 genera with 17 species were described, and 4 aptychi species were recorded. The ammonites belong to the suborders Haploceratina, Perisphinctina, Olcostephanina, and Ancyloceratina. Perisphinctids belong to the genera Pseudosubplanites, Hegaratella, Delphinella, Substeueroceras, Malbosiceras, and Strambergella. Based on the occurrence of Pseudosubplanites grandis, the studied section can be considered to belong to the Grandis ammonite Subzone of the upper part of the lower Berriasian. The association described here appears to be close to the coeval ammonite association in Crimea.

Biostratigraphy and Chronostratigraphy of Late Jurassic – Early Cretaceous in Selected Areas in Kurdistan Region, Northern Iraq

The biostratigraphy and chronostratigraphy of Late Jurassic–Early Cretaceous (Tithonian–Aptian) successions at three outcrops in the Kurdistan Region, northern and northeastern Iraq (Amadia, Gara, and Barsarin sections) are studied depending on ammonite, planktic, and benthic foraminiferal contents. The studied formations: Chia Gara, Sarmord, and Qamchuqa, are recorded in all studied localities, while Garagu and Balambo formations are exposed at some studied localities. Age determination of the Chia Gara Formation relied on the ammonite fauna. The ammonites investigated are the major assemblage fauna of the Durangites Zone, which corresponds to the Late Tithonian. The detailed planktic foraminiferal investigation in Balambo Formation permits the recognition of five well-defined zones, these are Favusella hoterivica Interval Zone, Hedbergella sigali Interval Zone, Globigerinelloides ferreolensis Interval Zone, Globigerinelloides blowi Interval Zone, and Globigerinelloides algeriana Taxon Range Zone (part), which reveal a Late Valanginian to Late Aptian age. The stratigraphic distribution of the benthic foraminifera shows three zones, these are Everticyclammina kelleri Assemblage Zone, Pseudocyclammina lituus Assemblage Zone, and Palorbitolina lenticularis Taxon Range Zone, the 1st and 2nd zones were recognized in the Sarmord Formation at Amadia section, which extends in age from late Valanginian to Hauterivian. While the 3rd zone is recorded from Qamchuqa Formation at the Gara section representing the Early Aptian age.

New material of heteromorph ammonites from the Lower Cretaceous of Lhozhag County, southern Tibet and its biostratigraphic implications

Cretaceous ammonites are still poorly known in Tibet, western China. Here we describe a new heteromorph ammonite fauna from the Lower Member of the Lakang Formation in the Lhozhag County, southern Tibet. Material of at least five genera are recognized, including Aspinoceras, ? Hemihoplites, Heteroceratidae gen. et sp. indet, ? Mortoniceras and Parancyloceras, among which three genera are reported from this area for the first time. This ammonite fauna indicates that the age of the Lakang Formation is approximately late Hauterivian to Albian (Early Cretaceous). This study proves that the Lakang Formation was not contemporaneous with the adjacent Gamba Group, which is slightly younger, different from a previous interpretation.

An account of the lower Aptian ammonites of the Niveau Goguel (= OAE 1a) in the Vocontian Basin, SE France

It has long been claimed that ammonites are scarce, if not completely absent, during the deposition of the Oceanic Anoxic Event 1a, locally known as the Niveau Goguel (NG), in the Vocontian Basin, SE France. Here we provide the first description of ammonites found within, and above, the NG from three Vocontian key sections (Saint-Jaume, Serre Chaitieu, and Les Sauzeries-Basses). The ammonite fauna studied represents almost a hundred of specimens, most of which have been collected in situ and calibrated with the high-resolution lithostratigraphical framework previously established in those sections. The following palaeontological identifications are by no means to be considered as definitive and many taxa are left in open nomenclature pending more materiel to be collected. The collected material gives evidence of the upper Deshayesites forbesi Zone during the deposition of the NG, as well as the upper Deshayesites deshayesi Zone and upper Dufrenoyia furcata Zone in the overlying strata, that around the Niveau Blanc sensu lato (NB s.s.).