Ammonite Research Articles

Cibolaites petraschecki sp. nov., a new collignoniceratine ammonite from the Brießnitz Formation of Saxony (Turonian, Elbtal Group, Germany)

Cibolaites petraschecki sp. nov., a new collignoniceratine ammonite from the Brießnitz Formation of Saxony (Turonian, Elbtal Group, Germany)

UPPER KIMMERIDGIAN AND TITHONIAN AMMONITES FROM THE TUNISIAN "DORSALE" (NE TUNISIA): UPDATED BIOSTRATIGRAPHY FROM THE JEBEL OUST

In the context of updating biostratigraphic analysis in the Upper Kimmeridgian-lowermost Berriasian from the whole of the Tunisian Dorsale (NE Tunisia), new results obtained from the Jebel Oust reference section are presented. The bed-by-bed-sampling of a rather rich ammonite fauna gathered in the two most favourable profiles in the area allowed to propose, for the first time, a biozonation for Upper Kimmeridgian to Tithonian limestones. Calpionellids relayed or completed ammonite assemblages, and were also useful for biostratigraphy in beds close to the Jurassic-Cretaceous boundary. The composition of ammonite assemblages, as well as the known ranges for genera and species, is in accordance with the available information from epioceanic areas in West-Mediterranean Tethys. The recognized biozones fit the standard proposal given by Groupe Francais D'Etude du Jurassique in 1997. Age-interpretation for turbiditic horizons in the Jebel Oust is made for the first time. In spite of some limitations, the biostratigraphic results obtained in Jebel Oust sections provide a valuable tool for potential correlations with poorly known sections in northern Tunisia, as well as with other Tethyan areas.

Two new Late Famennian kosmoclymeniid ammonoids from the Anti-Atlas of Morocco

Representatives of the family Kosmoclymeniidae belong to the most abundant ammonoids in the late Famennian seccessions of various regions, but they are much less common in the North African occurrences. In the following, the two new kosmoclymeniid species Kosmoclymenia ebbighauseni and Muessenbiaergia bockwinkeli are described from the Anti-Atlas of Morocco; both species are most probably from the Gonioclymenia assemblage.

Ammonites, Anoxia and Time

Ammonites, Anoxia and Time

NORIAN AMMONOIDS FROM THE NAYBAND FORMATION (IRAN) AND THEIR BEARING ON LATE TRIASSIC SEDIMENTARY AND GEODYNAMIC HISTORY OF THE IRAN PLATE

A Middle Norian (Alaunian 2) ammonoid assemblage from north of Esfahan (Central Iran) is described and chronostratigraphically evaluated. Formerly known as Distichites fauna, it represents a geographically widely distributed and stratigraphically important fossil level in the lower part of the Upper Triassic Nayband Formation. The new distichitid ammonoid genus Mesodistichites with the new species M. evolutus are introduced; additional faunal members are Noridiscites nodosus n. sp. and the leiostracean Stenarcestes diogenis and Pinacoceras cf. imperator. The Nayband Formation of the Esfahan region, belonging to the Zefreh-Soh Facies, is lithostratigraphically emended to contain three formally introduced members (Parsefid, Venher and Niazmargh members), which are all of Norian age, whereas Rhaetian sediments are missing. These members are correlated with Norian lithostratigraphic units of the type sequence of the formation in Nayband, eastern Iran. Integration of all Iranian Nayband data allows the recognition of three 3rd order sequences within this formation and the proof of a major pre- or syn-Jurassic unconformity across Central Iran and the Central-East Iranian Microcontinent (CEIM) related to the Main-Cimmerian event. Because of the latter and of major lithostratigraphic and facial differences, we propose to exclude the Nayband Formation from the Shemshak Group. A careful review of the available biostratigraphic data from northern and southern Iran let us further assume that the collision of the Iran Plate with Eurasia occurred in the later Early Carnian and was concurrent to the onset of the Carnian Humid Episode.

UPPER SPATHIAN TO BITHYNIAN (LOWER TO MIDDLE TRIASSIC) BRACHIOPODS FROM NORTH DOBROGEA (ROMANIA)

Brachiopods obtained from several Triassic localities in North Dobrogea, in Romania, are described. Upper Spathian and Aegean Hallstatt-type red limestones have been sampled in the Desli Caira section, proposed as the GSSP for the base of the Anisian. The Bithynian brachiopods mostly originate from the Tubiphytes -microbial buildup in the Mahmudia quarry, and also from the Hallstatt-type limestones of Agighiol and Orta Bair. Their age estimates are supported by ammonoids collected from the same beds. The upper Spathian and Aegean assemblages of Desli Caira consist of four rhynchonellids, with one genus and two species newly described, Ortarhynchia petersi gen. n. sp. n. and Austriellula iordanae sp. n. The Bithynian assemblages comprise the most diverse fauna, with 15 species, four species of which are newly described, Ortarhynchia petersi gen. n. sp. n., Piarorhynchella kittli sp. n., Ptychomentzelia dobrogeana sp. n. and P. simionescui sp. n. In the Tubiphytes facies of Mahmudia, the assemblage is numerically dominated by mentzeliids and dielasmatids, forming 84.8 % of the whole assemblage. Spiriferinids and rhynchonellids form the minor component. Instead, rhynchonellids prevail in the Hallstatt facies at Agighiol and Orta Bair. The assemblages described here are hardly comparable with those of the western Tethys. The Bithynian assemblage is very different from its equivalent described from the substage stratotype in Turkey. In North Dobrogea, the carbonate substrate and clear and agitated water supported an assemblage with high diversity. In contrast, in Bithynia, the brachiopod community dwelled on a softer and muddier substrate, with higher density and lower diversity. The locality of Aghdarband (Iran) also delivered Bithynian brachiopods, forming another different assemblage. The recovery and radiation of brachiopods after the P/T crisis is discussed in the framework of Palaeo-Tethyan palaeogeography, making comparisons with the South China localities.

AMMONITES OF THE SUBFAMILY ZAPALIINAE FROM THE LOWER TITHONIAN OF ESTANCIA MARÍA JUANA, VACA MUERTA FORMATION (PORTADA COVUNCO MEMBER), NEUQUÉN BASIN, ARGENTINA

A new collection of ammonites from the Picunleufuense Zone (standard base of the Andean Tithonian) of the locality Estancia Maria Juana (southern Neuquen Basin, Argentina) has provided abundant and well preserved material of new transients of Indansites picunleufuense and Choicensisphinctes platyconus. These transients are described and a detailed review of the early evolution of the Indansites lineage is presented. The meaning of changes in rib density, variations within the microconchs (males) and the length of the bodychamber in Indansites picunleufuense are discussed. It is concluded that the changes in rib density which characterize the successive macroconchs of the transients indicate changes in the rate of shell-growth. The more densely ribbed phragmocone of later transients would have had lower growth rates, which would also explain their smaller adult size. The microconchs show high variation in adult size suggesting high plasticity in the size-age maturation, most likely caused by influence of seasonal environmental conditions. A large small-macroconch-like lapetted microconch, coming from the close locality Picun Leufu, is interpreted as a new case of sex-change.

Gem-quality ammonites of Canada: Features of mining and processing

Gem-quality ammonites of Canada: Features of mining and processing

On the paleoecology of the index ammonites Baculites (Lamarck, 1799) and Scaphites (Parkinson, 1811) as revealed by a study of relatively rare epizoans

On the paleoecology of the index ammonites Baculites (Lamarck, 1799) and Scaphites (Parkinson, 1811) as revealed by a study of relatively rare epizoans

МЕСТОРОЖДЕНИЕ ЮВЕЛИРНЫХ АММОНИТОВ МОДИРОВАЛА, МАДАГАСКАР

МЕСТОРОЖДЕНИЕ ЮВЕЛИРНЫХ АММОНИТОВ МОДИРОВАЛА, МАДАГАСКАР

Ammonoids from the late Givetian Taouzites Bed of Ouidane Chebbi (eastern Tafilalt, SE Morocco)

Ammonoids from the late Givetian Taouzites Bed of Ouidane Chebbi (eastern Tafilalt, SE Morocco)

EARLY JURASSIC (SINEMURIAN TO BASAL TOARCIAN) AMMONITES OF THE BRESCIAN PREALPS (SOUTHERN ALPS, ITALY)

This work provides a more precise up-to-date biostratigraphical framework of the Early Jurassic ammonite succession of the Brescian Prealps with more than seventy taxa for the Sinemurian, Pliensbachian and basal Toarcian corresponding to a about 30 horizons or faunal assemblages rather well correlable with the NW European standard zonation. These results are supported with already published data, new data from recent field investigations, revised contributions of different authors and with the study of the historical collection of the Museum of Natural Sciences of Brescia (Northern Italy). The biohorizons are referred to the Lower Jurassic carbonate series of the Brescian Prealps, cropping out between the eastern surroundings of Brescia (Botticino-Serle), to the East, and the Lake Iseo, to the West. This area was located in the eastern border of the wide Lombardian Basin, a part of the southern continental passive margin subjected to the Jurassic rifting, preceding the Neo-Tethys opening.

Био-, магнито- и циклостратиграфия разреза верхнего берриаса у с. Алексеевка (Белогорский район, Республика Крым). Статья 1. Аммониты. Магнитостратиграфия. Циклостратиграфия.

Био-, магнито- и циклостратиграфия разреза верхнего берриаса у с. Алексеевка (Белогорский район, Республика Крым). Статья 1. Аммониты. Магнитостратиграфия. Циклостратиграфия.

The late Famennian tornoceratid ammonoids in the Anti-Atlas of Morocco

The late Famennian tornoceratid ammonoids in the Anti-Atlas of Morocco

Book review: Ammonoid paleobiology: From anatomy to ecology

Book review: Ammonoid paleobiology: From anatomy to ecology

The ammonoids from the Late Permian Paratirolites Limestone of Julfa (East Azerbaijan, Iran)

The Changhsingian (Late Permian), 4 to 5 m thick Paratirolites Limestone has yielded diverse ammonoid assemblages composed of the genera Neoaganides, Pseudogastrioceras, Dzhulfites, Paratirolites, Julfotirolites, Alibashites, Abichites, Stoyanowites and Arasella. The succession of ammonoid species allows for a subdivision of the rock unit into eight biozones, in ascending order: Dzhulfites zalensis Zone, Paratirolites trapezoidalis Zone, Paratirolites kittli Zone, Stoyanowites dieneri Zone, Alibashites mojsisovicsi Zone, Abichites abichi Zone, Abichites stoyanowi Zone and Arasella minuta Zone. The following 20 new species are described by two of us (DK and AG): Neoaganides ultimus sp. nov., Pseudogastrioceras relicuum sp. nov., Dzhulfites zalensis sp. nov., Dzhulfites hebes sp. nov., Paratirolites coronatus sp. nov., Paratirolites birunii sp. nov., Paratirolites quadratus sp. nov., Paratirolites multiconus sp. nov., Paratirolites serus sp. nov., Julfotirolites kozuri sp. nov., Alibashites ferdowsii sp. nov., Alibashites uncinatus sp. nov., Alibashites stepanovi sp. nov., Abichites subtrapezoidalis sp. nov., Abichites alibashiensis sp. nov., Abichites ariaeii sp. nov., Abichites paucinodus sp. nov., Abichites shahriari sp. nov., Abichites terminalis sp. nov. and Stoyanowites aspinosus sp. nov. After the time-equivalent Chinese occurrences, the material described here is the most diverse assemblage known from the critical interval before the end-Permian mass extinction.http://zoobank.org/urn:lsid:zoobank.org:pub:75D71EE8-27A2-48B1-805B-52E98578A7B8

The last ammonoids of Jordan – implications from the Outhriate section

The last ammonoids of Jordan – implications from the Outhriate section

AMMONOIDS FROM THE ZHUGANPO MEMBER OF THE FALANG FORMATION AT NIMAIGU AND THEIR RELEVANCE FOR DATING THE XINGYI FOSSIL-LAGERSTÄTTE (LATE LADINIAN, GUIZHOU, CHINA)

We herein document the various ammonoid faunas, of which 8 are newly described taxa, recently collected from the Falang Formation at Nimaigu (Wusha) near Xingyi (Guizhou, South China) and also define their biostratigraphy, correlation and age. The sampled interval includes the Zhuganpo Member, which contains the world famous Xingyi Fossil-Lagerstatte, and the lowermost part of the overlying Wayao Member. Ammonoids are quite abundant, but preservation is usually very poor. New genera Yangites , Haoceras and Sinomeginoceras are described on the basis of four new species. The new subfamily Haoceratinae (family Trachyceratidae) is erected to accommodate Haoceras and Sinomeginoceras . Xenoprotrachyceras , Detoniceras , Ptychites , Trachyceras and Clionitites are also recognized, together with a specimen attributed with doubt to Parasturia . Most of the faunas are endemic and typical representatives of Upper Ladinian ammonoid zones have not been recognized. A new local biostratigraphic scale is proposed, consisting of the Haoceras xingyiense zone, Trachyceras beds and Trachyceras multituberculatum zone, in stratigraphic order. The Trachyceras beds and the Trachyceras multituberculatum zone are attributed to the Lower Carnian, but most of the bio-chronostratigraphic analysis is focused on the Haoceras xingyiense zone, because it directly overlies the vertebrate-bearing interval. Correlation of the new biozone is discussed and its stratigraphic position is referred, at least in part, to the lower Sutherlandi Zone of the North American scale. This correlation pinpoints the age of the Xingyi Fossil-Lagerstatte as middle Late Ladinian, which until now had been a matter of debate for 30+ years.

Late Givetian ammonoids from Ait Ou Amar (northern Maider, Anti-Atlas, southeastern Morocco)

Late Givetian ammonoids from Ait Ou Amar (northern Maider, Anti-Atlas, southeastern Morocco)

Cenomanian ammonites from Santander (Cantabria) and Sopeira (Aragón, southcentral Pyrenees), northern Spain

Ammonites del Cenomaniense de Santander (Cantabria) y de Sopeira (Aragon, Pirineos centro-meridionales), Espana septentrional. Se describen por primera vez ammonites del Cenomaniense superior (Cretacico) de los alrededores de Santander y de Sopeira (provincia de Huesca), Espana septentrional. Las siguientes especies estan presentes: Tetragonites subtimotheanus Wiedmann, 1962, Calycoceras ( Newboldiceras) asiaticum asiaticum (Jimbo, 1894), Calycoceras ( Newboldiceras) planecostatum (Kossmat, 1897), Eucalycoceras pentagonum (Jukes-Browne, 1896), Eucalycoceras jeanneti Collignon, 1937 y Thomelites sornayi (Thomel, 1966). Esta asociacion es tipica de la parte inferior del Cenomaniense superior de la zona de Calycoceras (Proeucalycoceras) guerangeri a excepcion de E. jeanneti, conocido solamente de Madagascar.