|
Reynesocoeloceratinae
The subfamily Reynesocoeloceratinae comprises early Jurassic ammonite genera that lived during Pliensbachian stage. These dactylioceratids existed from Ibex ammonite zone and died out in Spinatum zone. They have evolved from '' Metaderoceras'' and gave rise to subfamily Dactylioceratinae. Description Ammonites with depressed, cadicone, or even evolute, serpenticone shells. Tubercules might be present. Ribs can be both single, or bifurcating. Some members of this subfamily show size dimorphism. They differs from Dactylioceratinae by suture. While Reynesocoeloceratinae has on dorsal side of external lobe two major secondary lobes, this is not so in Dactylioceratinae, as there is external saddle not divided, while lateral lobe is strongly trifid. Taxonomy *Reynesocoeloceratinae Dommergues, 1986 **''Reynesocoeloceras'' Géczy, 1976 **''Bettoniceras'' Wiedenmayer, 1977 **''Prodactylioceras'' Spath, 1923 **''Cetonoceras ''Cetonoceras'' is genus of ammonite that lived during the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dactylioceratidae
The family Dactylioceratidae comprises Early Jurassic ammonite genera with ribbed and commonly tuberculate shells that resembled later Middle Jurassic stephanoceratids and Upper Jurassic perisphinctids. Shells may be either evolute or involute. Description Ammonites with evolute, serpenticone to cadicone shells with ribs, sometimes with tubercules. Members of this family had no keels. while homeomorphic with stephanoceratids and perisphinctids, they had unique shell structure with double shells and flat-topped ribs on the inner shell. Based on suture differences, they are divided into 2 subfamilies. Reynesocoeloceratinae possess two major secondary lobes in dorsal side of external saddle. This saddle is not divided this way in Dactylioceratinae, while lateral lobe is deeply trifid. Evolution It has been suggested, that this family is polyphyletic, but this is now considered to be false. Reynesocoeloceratinae evolved in lower Pliensbachian from '' Metaderoceras'' and died o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dactylioceratinae
The subfamily Dactylioceratinae comprises early Jurassic ammonite genera that lived during Upper Pliensbachian to Upper Toarcian stage. These dactylioceratids existed from Margaritatus ammonite Zone, when they have evolved from Reynesocoeloceratinae and died out in Variabilis Zone without leaving any descendants. Description While ribs can be single, they are mostly bifurcating at ventrolateral edge and in some genera, even fibulation (primary ribs are joining at ventrolateral tubercules) can exist. Tubercules might also be present at ventrolateral edge, but not in all species. Final aperture is contracted. Size dimorphism is common. Taxonomy Taxonomic composition of this subfamily differs among literature. Well known is taxonomy according to Treatise on Invertebrate Paleontology, which is shown below with addition of ''Tokurites'', which has not been known in the time, when current edition of Treatise has been published. *''Reynesoceras'' Spath, 1936 *''Dactylioceras'' Hya ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus '' Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should clearly demons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Jurassic
The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event, 201.3 Ma (million years ago), and ends at the start of the Middle Jurassic 174.1 Ma. Certain rocks of marine origin of this age in Europe are called "Lias Group, Lias" and that name was used for the period, as well, in 19th-century geology. In southern Germany rocks of this age are called Black Jurassic. Origin of the name Lias There are two possible origins for the name Lias: the first reason is it was taken by a geologist from an England, English quarryman's dialect pronunciation of the word "layers"; secondly, sloops from north Cornwall, Cornish ports such as Bude would sail across the Bristol Channel to the Vale of Glamorgan to load up with rock from coastal limestone quarries (lias limestone from S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonitida
Ammonitida is an order of ammonoid cephalopods that lived from the Jurassic through Paleocene time periods, commonly with intricate ammonitic sutures. Ammonitida is divided into four suborders, the Phylloceratina, Lytoceratina, Ancyloceratina, and Ammonitina. The Phylloceratina is the ancestral stock, derived from the Ceratitida near the end of the Triassic. The Phylloceratina gave rise to the Lytoceratina near the beginning of the Jurassic which in turn gave rise to the highly specialized Ancyloceratina near the end of the Jurassic. Both the Phylloceratina and Lytoceratina gave rise to various stocks combined in the Ammonitina. These four suborders are further divided into different stocks, comprising various families combined into superfamilies. Some like the Hildoceratoidea and Stephanoceratoidea are restricted to the Jurassic. Others like the Hoplitoidea and Acanthoceratoidea are known only from the Cretaceous. Still others like the Perisphinctoidea are found in both. R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pliensbachian
The Pliensbachian is an age of the geologic timescale and stage in the stratigraphic column. It is part of the Early or Lower Jurassic Epoch or Series and spans the time between 190.8 ± 1.5 Ma and 182.7 ± 1.5 Ma (million years ago). The Pliensbachian is preceded by the Sinemurian and followed by the Toarcian. The Pliensbachian ended with the extinction event called the Toarcian turnover. During the Pliensbachian, the middle part of the Lias was deposited in Europe. The Pliensbachian is roughly coeval with the Charmouthian regional stage of North America. Stratigraphic definitions The Pliensbachian takes its name from the hamlet of Pliensbach in the community of Zell unter Aichelberg in the Swabian Alb, some 30 km east of Stuttgart in Germany. The name was introduced into scientific literature by German palaeontologist Albert Oppel in 1858. The base of the Pliensbachian is at the first appearances of the ammonite species '' Bifericeras donovani'' and genera ''Apoderocer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reynesocoeloceras
''Reynesocoeloceras'' is genus of ammonite that lived during the lower Pliensbachian stage of early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ..., ammonite zones Ibex—Davoei. Distribution Fossils of this genus are found in Europe, North America, South America and north Africa.Paleobiology Database - Reynesocoeloceras 2017-10-16. Description Shells of ammonites belonging to this genera had evolute cadicone whorls with depressed section. Venter has been flat. Ribs were usually single. On the ventrolateral tubercules, which could ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bettoniceras
''Bettoniceras'' is genus of ammonite that lived during the Pliensbachian stage of the early Jurassic. It evolved from '' Reynesocoeloceras'' in Davoei ammonite zone and died out during Margaritatus zone. It is possible that ''Prodactylioceras ''Prodactylioceras'' is genus of ammonite that lived during the Pliensbachian stage of early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the e ...'' evolved from this genus. Fossils of this genus have been found in Europe, Morocco, Tunisia, and Chile. Sometimes this genus is not considered valid, but just as a synonym of ''Prodactylioceras''. Description Ammonites of this genus had serpenticone planulate shells with mostly single ribs and no tubercules. Whorl section was round. Only difference between ''Prodactylioceras'' and ''Bettoniceras'' is that latter is missing tubercules. References Dactylioceratidae Pliensbachian l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prodactylioceras
''Prodactylioceras'' is genus of ammonite that lived during the Pliensbachian stage of early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J .... It has evolved from '' Reynesocoeloceras'', but maybe not directly, but through '' Bettoniceras''. Its fossils were found in Europe, Asia and North America. While sometimes, genus ''Bettoniceras'', which differs from ''Prodactylioceras'' only by lacking tubercules is considered valid, in other cases it is considered to be a synonym of this genus.Meister, C., Dommergues, J. L., Dommergues, C., Lachkar, N., & El Hariri, K. (2011). Les ammonites du Pliensbachien du jebel Bou Rharraf (Haut Atlas oriental, Maroc). Geobios, 44(1), 117-e1. Species as ''P. italicum'', or ''P. colubriforme'' would not be in that case belonging to this gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cetonoceras
''Cetonoceras'' is genus of ammonite that lived during the upper Pliensbachian stage of early Jurassic. Fossils of this genus were found in Italy, France, Spain, Portugal, Hungary and Austria.Géczy, B., Meister, C. 1998. Les ammonites du Domérien de la montagne du Bakony (Hongrie). Revue de Paléobiologie 17(1):69-161 Description First whorls of shell are depressed, but then they became rounded and more compressed. Primary ribs are strong and they are usually bifurcating. Secondary ribs are more delicate. Tubercules are present on ventrolateral positions in younger whorls, but they are diminishing on outer whorls. Similar genus is ''Reynesocoeloceras ''Reynesocoeloceras'' is genus of ammonite that lived during the lower Pliensbachian stage of early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) ...'', but that one is lacking ribs bifurcations.Blau, J., Meister C. (1991). Lias ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pliensbachian Life
The Pliensbachian is an age (geology), age of the geologic timescale and stage (stratigraphy), stage in the stratigraphic column. It is part of the Early Jurassic, Early or Lower Jurassic epoch (geology), Epoch or series (stratigraphy), Series and spans the time between 190.8 ± 1.5 annum, Ma and 182.7 ± 1.5 Ma (million years ago). The Pliensbachian is preceded by the Sinemurian and followed by the Toarcian. The Pliensbachian ended with the extinction event called the Toarcian turnover. During the Pliensbachian, the middle part of the Lias Group, Lias was deposited in Europe. The Pliensbachian is roughly coeval with the Charmouthian regional stage of North America. Stratigraphic definitions The Pliensbachian takes its name from the hamlet of Pliensbach in the community of Zell unter Aichelberg in the Swabian Alb, some 30 km east of Stuttgart in Germany. The name was introduced into scientific literature by German palaeontologist Albert Oppel in 1858. The base of the Pliens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
