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Euomphalidae
Euomphalidae is an extinct family of Paleozoic to early Mesozoic marine molluscs which may be gastropods with anisostrophically coiled shells (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). The shells show a selenizone. Genera Genera in the family Euomphalidae include: , accessed 12 August 2009. * '' Acanthonema'' * '' Alaionema'' * '' |
Cylicioscapha
''Cylicioscapha'' is an extinct genus of fossil mollusk, probably a gastropod, a robust-looking euomphalid from the upper Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ... of North America. Description The shell is depressed on both the upper and lower sides; the outer rim is flattish, knobby along the upper edge; the aperture, is more or less trapezoidal. References *J. Brooks Knight et al. 1960. Systematic Descriptions. Treatise on Invertebrate Paleontology Part I Mollusca 1. Geological Society of America and University of Kansas Press. Euomphalidae Pennsylvanian first appearances Guadalupian genus extinctions Carboniferous gastropods Permian gastropods {{paleo-gastropod-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphiscapha
''Amphiscapha'' is a fossil gastropod mollusk, or less likely a monoplacophoran, genus from the Pennsylvanian and Lower Permian of North and South America, included in the family Euomphalidae Euomphalidae is an extinct family of Paleozoic to early Mesozoic marine molluscs which may be gastropods with anisostrophically coiled shells (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). The shells show a selenizone .... It is sometimes regarded as a subgenus of '' Straparollus'', ''S. (Amphiscapha)'' Knight 1942 Description The shell in this genus is hyper strophic discoidal, with a flat base and a concave upper side. The location of what is presumed to be the exhalent channel is marked by a smooth or rugose ridge along the upper-outer margin, which lies along the edge of a flat to concave outer rim. References *J. B. Knight et al. 1960. Systematic descriptions; Treatise on Invertebrate Paleontology; Part I, Mollusca(1): ''I''192.Paleobiology database ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euomphalus Pentangulatus
''Euomphalus'' is a genus of fossil marine gastropods known to have lived from the Silurian to the Middle Permian.J.B.Knight,et al 1960. Treatise on Invertebrate Paleontology, Part I, Mollusca 1, ch on systematic descriptions. Geol Soc of America and Univ Kansas Press.(in Czech) Pek I., Vašíček Z., Roček Z., Hajn. V. & Mikuláš R.: ''Základy zoopaleontologie''. - Olomouc, 1996. 264 pp., . Description ''Euomphalus'' is characterized by a closely coiled shell with a depressed to slightly elevated spire and a channel-bearing angulation (a selenizone) on the upper surface of the whorls. The lower surface of the whorls is rounded to angular. '' Amphiscapha'', '' Philoxene'', and '' Straparollus'' are among similar related genera. '' Serpulospira'', also related, differs in having a broadly open spiral in the adult form. Taxonomy ''Euomphalus'' is the type genus of the family Euomphalidae Euomphalidae is an extinct family of Paleozoic to early Mesozoic marine molluscs w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centrifugus
†''Centrifugus'' is an extinct species of fossil sea snail, a marine gastropod mollusk in the family Euomphalidae, which paleontologists place in the order Archaeogastropoda. This species was originally known from the Upper Silurian of northern Europe (Gotland). Description The shell has a nearly flat spire, and is widest across the base, which is marked by a peripheral keel. The upper side of the aperture has a narrow slit, and a selenizone A selenizone (from the Greek "selene" meaning "moon", and "zone" meaning "girdle") is an anatomical structure that exists in the shells of some families of living sea snails: the slit shells, the little slit shells and the abalones, which are m ... located close to the upper suture. Five strong spiral cords alternating with weaker ones cover the upper surface of the shell. References * J.Brooks Knight et al. 1960. Systematic Descriptions. Treatise on Invertebrate Paleontology Part I Mollusca 1. Geological Society of America and Univ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coelodiscus
''Ceolodiscus'' is a genus in the gastropod family Euomphalidae from the Lower and Middle Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), 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 J ... of Europe. The shell is small but stocky; involute or with a slightly protruding spire. Whorls are generally smooth, evenly rounded and slightly overlapping; umbilicus deep, aperture ovate.Teichert, S., & Nützel, A. (2015). Early Jurassic anoxia triggered the evolution of the oldest holoplanktonic gastropod Coelodiscus minutus by means of heterochrony. ''Acta Palaeontologica Polonica'', 60(2), 269–276. Is the oldest known holoplanktonic gastropod, thanks to a bilateral symmetrical shells as an adaption to active swimming. Also the most common of the sea snails of the Posidonienschiefer Formation, it is also one of the most varied ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euomphalus
''Euomphalus'' is a genus of fossil marine gastropods known to have lived from the Silurian to the Middle Permian.J.B.Knight,et al 1960. Treatise on Invertebrate Paleontology, Part I, Mollusca 1, ch on systematic descriptions. Geol Soc of America and Univ Kansas Press.(in Czech) Pek I., Vašíček Z., Roček Z., Hajn. V. & Mikuláš R.: ''Základy zoopaleontologie''. - Olomouc, 1996. 264 pp., . Description ''Euomphalus'' is characterized by a closely coiled shell with a depressed to slightly elevated spire and a channel-bearing angulation (a selenizone) on the upper surface of the whorls. The lower surface of the whorls is rounded to angular. ''Amphiscapha'', '' Philoxene'', and '' Straparollus'' are among similar related genera. '' Serpulospira'', also related, differs in having a broadly open spiral in the adult form. Taxonomy ''Euomphalus'' is the type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the famil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxonomy Of The Gastropoda (Bouchet & Rocroi, 2005)
The taxonomy of the Gastropoda as it was revised in 2005 by Philippe Bouchet and Jean-Pierre Rocroi is a system for the scientific classification of gastropod mollusks. (Gastropods are a taxonomic class of animals which consists of snails and slugs of every kind, from the land, from freshwater, and from saltwater.) The paper setting out this taxonomy was published in the journal ''Malacologia''. The system encompasses both living and extinct groups, as well as some fossils whose classification as gastropods is uncertain. The Bouchet & Rocroi system was the first complete gastropod taxonomy that primarily employed the concept of clades, and was derived from research on molecular phylogenetics; in this context a clade is a "natural grouping" of organisms based upon a statistical cluster analysis. In contrast, most of the previous overall taxonomic schemes for gastropods relied on morphological features to classify these animals, and used taxon ranks such as order, superorder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenizone
A selenizone (from the Greek "selene" meaning "moon", and "zone" meaning "girdle") is an anatomical structure that exists in the shells of some families of living sea snails: the slit shells, the little slit shells and the abalones, which are marine gastropod mollusks from ancient lineages. It is a spiral band of crescentric growth lines or threads (lunulae) on the shell surface due to the semicircular end of a notch or slit on the outer lip. A structure of the same type exists in several fossil groups of mollusks, including all the fossil families of slit shells, as well as three superfamilies of what may have been gastropods, but may possibly have been monoplacophorans or paragastropods instead. The function of the holes and slits in living sea snails is to allow for exhalant water circulation, which is important for respiration and other functions. It has also been suggested that the selenizone may serve to reinforce the shell against catastrophic breakage during predati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
