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Bihenduloceras
''Bihenduloceras'' is an Upper Jurassic perisphinctacean ammonite and member of the olcostephanid subfamily Spiticeratine. Its shell has a subquadrate whorl section, flattended venter, and fine ribs that spring in bundles from large umbilical tubercles. References ;Notes ;Bibliography *Arkell, et al., 1957. Mesozoic Ammonoidea; Treatise on Invertebrate Paleontology, Part L. Geological Society of America and University of Kansas Press. Perisphinctoidea Jurassic ammonites Tithonian life {{Ammonite-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perisphinctaceae
Perisphinctoidea, formerly Perisphinctaceae, is a superfamily of Middle Jurassic (Bajocian) to Lower Cretaceous (Barremian) ammonites, commonly with evolute shells with strong ribbing that typically divides about mid flank before crossing the venter. Classification Some 16 families have been recognized in the Perisphinctoidea. The following is based on Donovan ''et al.'' 1981Donovan, Callomon and Howarth 1981 Classification of the Jurassic Ammonitina; Systematics Association. with modification from the Treatise on Invertebrate Paleontology, Part L (1957) *Perisphinctidae: Middle and Upper Jurassic root stock, derived from the Stephanoceratidae (Middle Jurassic direct derivatives of the Perisphinctidae) * Morphiceratidae * Tulitidae *Reineckeiidae *Pachyceratidae *Aspidoceratidae (early Upper Jurassic (Oxfordian) derivatives of Perisphinctidae) *Aulacostephanidae *Ataxioceratidae (mid Upper Jurassic (Kimmeridgian) derivatives of the Ataxioceratidae) * Dorsoplanitidae * V ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perisphinctoidea
Perisphinctoidea, formerly Perisphinctaceae, is a superfamily of Middle Jurassic (Bajocian) to Lower Cretaceous (Barremian) ammonites, commonly with evolute shells with strong ribbing that typically divides about mid flank before crossing the venter. Classification Some 16 families have been recognized in the Perisphinctoidea. The following is based on Donovan ''et al.'' 1981Donovan, Callomon and Howarth 1981 Classification of the Jurassic Ammonitina; Systematics Association. with modification from the Treatise on Invertebrate Paleontology, Part L (1957) * Perisphinctidae: Middle and Upper Jurassic root stock, derived from the Stephanoceratidae (Middle Jurassic direct derivatives of the Perisphinctidae) * Morphiceratidae * Tulitidae * Reineckeiidae *Pachyceratidae * Aspidoceratidae (early Upper Jurassic (Oxfordian) derivatives of Perisphinctidae) *Aulacostephanidae *Ataxioceratidae (mid Upper Jurassic (Kimmeridgian) derivatives of the Ataxioceratidae) * Dorsoplanitidae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic Ammonites
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined. By the beginning of the Jurassic, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
