Acrioceratidae

	Acrioceratidae Acrioceratidae is a family of heteromorph ammonites included in the Ancyloceratoidea comprising ancyloceratid-like forms that start off with a coiled juvenile section, followed by a straight or curved shaft ending in a hook. Two described genera are included, ''Acrioceras'' and '' Dissimilites''. The Acrioceratidae form a link, or evolutionary transition, between the loosely coiled Crioceratidae and the commonly tuberculate and heavy hooked Ancyloceratidae. Although resembling ''Acrioceras'' in general form, '' Toxancyloceras'' is included in the Ancyloceratidae where it resides as a transitional form. The primary morphological distinction between the Acrioceratidae and Ancycloceratidae is that the Acrioceratidae generally lack the tubercles and spines characteristic of the ancyloceratids. They differ from the ancestral Crioceratidae in that, like the Ancyloceratidae, they are truly heteromorphic (crioceratids aren't) with distinct growth phases. The Treatise on Invertebr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Ancyloceratoidea Ancyloceratoidea, formerly Ancylocerataceae, is a superfamily of typically uncoiled and loosely coiled heteromorph ammonoids Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ... established by Alpheus Hyatt in 1900, that may contain as many as 11 families, depending on the classification accepted. Taxonomy The taxonomy content, Family (biology), families, of the Ancycloceratoidea has grown over the year, partly with the addition of newly defined families and partly with the moving of families from other superfamilies. Arkell, ''et al.'' (1957) in the Treatise on Invertebrate Paleontology, Treatise Part L included just the Ancyloceratidae Meek 1876, Bochianitidae Spath 1922, Hemihoplitidae Spath 1924, and Heteroceratidae Hyatt 1900 within the Ancylocerataceae. The Crioceratitidae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Crioceratidae The Crioceratidae constitute a family of loosely to closely coiled Ammonitida included in the Ancyloceratoidea that lived during the Early Cretaceous; characterized by '' Crioceratites'' and other genera such as '' Hoplocrioceras'' and '' Paracrioceras''. The Crioceratidae are gyroconic, coiled in a plane, generally with space between the whorls although in some like ''Balearites'' the whorls are barely in contact. Although distinct in character and not truly heteromorphic the Crioceratidae were included in the American TreatisePart L, 1957, in the Ancyloceratidae as the subfamily Crioceratinae. It is now considered a distinct family as originally proposed by Wright 1952 with the Acrioceratidae Acrioceratidae is a family of heteromorph ammonites included in the Ancyloceratoidea comprising ancyloceratid-like forms that start off with a coiled juvenile section, followed by a straight or curved shaft ending in a hook. Two described gener ..., proposed by Vermeulen (2004), a t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Hauterivian The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.9 ± 2 Ma and 129.4 ± 1.5 Ma (million years ago). The Hauterivian is preceded by the Valanginian and succeeded by the Barremian.See Gradstein ''et al.'' (2004) for a detailed geologic timescale Stratigraphic definitions The Hauterivian was introduced in scientific literature by Swiss geologist Eugène Renevier in 1873. It is named after the Swiss town of Hauterive at the shore of Lake Neuchâtel. The base of the Hauterivian is defined as the place in the stratigraphic column where the ammonite genus ''Acanthodiscus'' first appears. A reference profile for the base (a GSSP) was officially ratified by the International Union of Geological Sciences in December of 2019, and is placed in La Charce, France. The top of the Hauterivian (the base of the Barremian) is at the first appearance of ammonite species ''Spitidiscus hugii'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded by the Hauterivian and followed by the Aptian Stage.See Gradstein ''et al.'' (2004) or the online geowhen database (link below) Stratigraphic definitions The original type locality for the Barremian Stage is in the vicinity of the village of Barrême, Alpes-de-Haute-Provence, France. Henri Coquand defined the stage and named it in 1873. The base of the Barremian is determined by the first appearance of the ammonites ''Spitidiscus hugii'' and ''Spitidiscus vandeckii''. The end of the Barremian is determined by the geomagnetic reversal at the start of the M0r chronozone, which is biologically near the first appearance of the ammonite '' Paradeshayesites oglanlensis''. Regional equivalents The Barremian falls in the Gallic epoch, a su ... [...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]
	Acrioceras ''Acrioceras'' is an extinct genus of cephalopods belonging to the ammonite subclass. with and (1996), ''Mollusca 4 Revised , Cretaceous Ammonoidea'', vol. 4, in ''Treatise on Invertebrate Paleontology'', Part L (Roger L. Kaesler et el. eds.), Boulder, Colorado: The Geological Society of America & Lawrence, Kansas: University of Kansas Press, pp. 223, 224. Description A spire of one or two loosely coiled whorls followed by a short or long, straight or curved shaft, terminal hook, and short and or long final shaft. The ribs are generally fine and untuberculate, but sometimes the major ribs are enlarged and are carrying one to three tubercles. The ribs are single on the spire or the shaft but may branch from umbilical tubercles on the hook and the final shaft. The dorsum tends to become flat and the dorsolateral margin to become angular on the shaft and the hook. with and (1996), ''Mollusca 4 Revised , Cretaceous Ammonoidea'', vol. 4, in ''Treatise on Invertebrate Pale ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Ancyloceratidae Ancyloceratidae is a family of heteromorphic Ammonitida, ammonites that lived during the Early Cretaceous. Their shells begin as a loose spiral with whorls not touching which then turns into a straight shaft that ends in a J-shape hook or bend at end. Coarse ribbing and spines are common. Ancyloceratidae is the type family for the Ancyloceratoidea and of the suborder Ancyloceratina. They are found in Lower Cretaceous, Barremian to perhaps Lower Albian sediments. Genera include: ''Ammonitoceras'' Dumas, 1876 ''Ancyloceras'' D'Orbigny, 1842 - type genus ''Ancylotropaeum'' Casey, 1980 ''Antarcticoceras'' Thomson, 1974 M.R.A. Thomson, « Ammonite faunas of the Lower Cretaceous of south-eastern Alexander Island », ''British Antarctic Survey Scientific Reports'', 80 (1974), p.1-44. ''Audouliceras'' Thomel, 1965 ''Australiceras'' Whitehouse, 1926 ''Caspianites'' Casey, 1961 ''Epancyloceras'' Spath, 1930 ''Epitroapeum'' Kakabadze, 1977 ''Helicancyloceras'' Klinger & Kennedy, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]