The Albian–Cenomanian boundary at Eggardon Hill, Dorset (England): an anomaly resolved?
8
Citation
15
Reference
10
Related Paper
Citation Trend
Keywords:
Cenomanian
Ammonite
Conglomerate
Stratigraphic unit
Abstract The lower–upper Cenomanian boundaries interval of the Nouader site in the Aures Basin (NE Algeria) has been studied for the first time using the association of two particularly effective taxonomic groups, one macrofossil (ammonites), and the other microfossil (foraminifera). The study section is divided into two formations (Fahdene and Bahloul) and one member (Annaba). Biostratigraphicaly, six ammonite biozones and five foraminiferan biozones were identified and calibrated. The ammonite fauna allows recognition of the lower Cenomanian Mantelliceras mantelli Zone, the upper lower Cenomanian Mantelliceras dixoni Zone, the succeeding lower middle Cenomanian Cunningtoniceras inerme Zone, the Acanthoceras rhotomagense Zone and its subzones of Turrilites costatus and Turrilites acutus , followed by the upper middle Cenomanian Acanthoceras amphibolum Zone, the lower upper Cenomanian Eucalycoceras pentagonum Zone and finally the lower Turonian Pseudaspidoceras flexuosum Zone. The foraminiferan biozones are respectively: Thalmanninella brotzeni Zone, Thalmanninella reicheli Zone, Rotalipora cushmani Zone, Whiteinella archaeocretacea Zone and Helvetoglobotruncana helvetica Zone. Among 14 ammonite zones in the Tethyan domain versus 11 in the Boreal domain, seven are common to both domains. For the planktonic foraminifera the Tethyan domain has five zones, the Boreal domain also has five, with five in common. The succession of index species occurs in the same order in both Tethyan (NE Algeria and Central Tunisia) and Boreal realms (East and NW Europe). Furthermore, the supposed depositional setting is interpreted as a calm and relatively deep environment which can be located around the middle to the external platform.
Cenomanian
Ammonite
Biozone
Cite
Citations (12)
The ammonite fauna of the Plenus Marls and Middle Chalk (Upper Cenomanian and Turonian) is described; it comprises 49 species and subspecies (8 new), referred to 27 genera. These provide a basis for revision of the ammonite zonation of the Upper Cenomanian and Turonian of Great Britain and correlation with the sequences in the Paris Basin and the stratotype areas in Sarthe and Touraine. It is demonstrated that the Cenomanian—Turonian boundary is best taken between the Neocardioceras juddii Zone below and the Watinoccras coloradoense Zone above.
Ammonite
Cenomanian
Marl
Ammonoidea
Stratotype
Cite
Citations (93)
A specimen referable to an Early Jurassic ammonite, Cleviceras cf. chrysanthemum (Yokoyama, 1904), was discovered from a limestone conglomerate layer of the Kuzu Complex in the Ashio Belt, central Japan. Cleviceras chrysanthemum, a species comparable to the present specimen, is a diagnostic ammonite of early Toarcian age in the Circum-Pacific. The limestone conglomerate layer in question is a part of a sequence composed of, from top to bottom, siliceous shale, limestone conglomerate itself, calcareous sandstone, and again siliceous shale. The siliceous shale above and below the ammonite-bearing conglomerate bed carries radiolarian fossils which indicate the Unuma echinatus Assemblage Zone or Tricolocapsa plicarum Zone of Middle Jurassic age. The whole sequence is judged to be normally superposed by frequently observable normal graded bedding. Thus, the age indicated by the fossil ammonite for the limestone conglomerate is in contradiction with the age of the overlying and underlying beds. These facts suggest that the ammonitebearing pebble of Early Jurassic age is a fragment transported from elsewhere and redeposited in its present position during a Middle Jurassic time. The description of the ammonite is given.
Conglomerate
Ammonite
Cite
Citations (3)
Ammonite
Cenomanian
Cite
Citations (19)
A specimen of ammonite obtained by Toshio Shimanuki from the lower Cenomanian (Cretaceous) outcrop in the Hobetsu district of Hokkaido, northern Japan, represents a new species of Lewesiceras (Pachydiscidae). In as much as Cenomanian specimens hitherto reported under Lewesiceras have been too immature for precise generic assignment, the present specimen is large enough to reach the adult stage. It represents a new species of Lewesiceras, and shows in some respects a step in the evolutionary change of characters from late Albian Eopachydiscus to the typical Turonian species of Lewesiceras.(Contributed by Tatsuro MATSUMOTO, M. J. A., Sept. 12, 2003)
Ammonite
Cenomanian
Outcrop
Cite
Citations (3)
A detailed taxonomic analysis has been carried out including the Acanthoceratidae family ammonoids collected in the mate- rials of the upper Cenomanian and lower Turonian appearing in the location of Puentedey, as weIl as in other sections belonging to neighbouring towns. All of them are located in northem Spain. Nineteen cephalopod genera and twenty-eight species have been identified, among which eight genera and fifteen species are included in the family Acanthoceratidae. Some of them are found in Spain for the first time, such as Euomphaloceras euomphalum and Fagesia catinus species. This research has made it possible to develop a biostratigraphic section which represents the observed cephalopod succession in the materials from the upper Cenomanian to the lower Turonian of Puentedey Formation series type, where eight ammonite biohorizons have been identified. This has enabled us to establish its zonal division. In the upper Cenomanian, three ammonite bioestratigraphic zones have been identified: Calycoceras (Calycoceras) naviculare, Metoicoceras geslinianum and Spathites (Jeanrogericeras) sub- conciliatus. The first one had not previously been used in the Basque-Cantabrian Basin and in it, the ammonite biohorizons Calyco- ceras (Calycoceras) naviculare and Neolobites vibrayeanus have been differentiated, whereas in the second one, two biohorizons have been characterized: Metoicoceras muelleri and Metoicoceras geslinianum. In the Lower Turonian the Choffaticeras quaasi and Mammites nodosoides zones have been identified, the first one including the Choffaticeras quaasi and Spathites (Ingridella) malla-
Ammonite
Cenomanian
Cephalopod
Ammonoidea
Cite
Citations (1)
Abstract A restudy of the Cenomanian ammonites of the Nice area, southeast of the Maritime Alps (France), suggests that the conclusion of H. Parent (1945) that the fauna of the upper Cenomanian also occurs in the lower Cenomanian is erroneous. Actually the ammonite zones here conform with those of the rest of the world. Reexamination of Parent's specimens showed that they were too poorly preserved to be identified specifically or, at times, even generically. Subsequent revision of the Chateauneuf fauna revealed that it was entirely lower Cenomanian with the exception of Calycoceras boulei Coll. The locality north of Peille is chosen as the type locality for the Nice Cenomanian. The ammonite zones of the Iberian peninsula, the southeast Maritime Alps, and Madagascar are correlated in a table.
Cenomanian
Ammonite
Table (database)
Peninsula
Cite
Citations (3)
Abstract Brachauchenine pliosaurids were a cosmopolitan clade of macropredatory plesiosaurs that are considered to represent the only pliosaurid lineage that survived the faunal turnover of marine amniotes during the Jurassic- Cretaceous transition. However, the European record of the Early to early Late Cretaceous brachauchenines is largely limited to isolated tooth crowns, most of which have been attributed to the classic Cretaceous taxon Polyptychodon. Nevertheless, the original material of P. interruptus, the type species of Polyptychodon, was recently reappraised and found undiagnostic. Here, we describe a collection of twelve pliosaurid teeth from the upper Albian-middle Cenomanian interval of the condensed, phosphorite-bearing Cretaceous succession at Annopol, Poland. Eleven of the studied tooth crowns, from the Albian and Cenomanian strata, fall within the range of the morphological variability observed in the original material of P. interruptus from the Cretaceous of England. One tooth crown from the middle Cenomanian is characterized by a gently subtrihedral cross-section. Similar morphology has so far been described only for pliosaurid teeth from the Late Jurassic and Early Cretaceous. Even though it remains impossible to precisely settle the taxonomic distinctions, the studied material is considered to be taxonomically heterogeneous.
Cenomanian
Tooth crown
Cite
Citations (15)
Cenomanian
Ammonite
Cite
Citations (16)