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Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bivalves
Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bivalves have no head and they lack some usual molluscan organs, like the radula and the odontophore. They include the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater. The majority are filter feeders. The gills have evolved into ctenidia, specialised organs for feeding and breathing. Most bivalves bury themselves in sediment, where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other hard surfaces. Some bivalves, such as the scallops and file shells, can swim. The shipworms bore into wood, clay, or stone and live inside these substances. The shell of a bivalve is composed of calc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otoscaphites
''Yezoites'' is an extinct genus of ammonites placed in the family Scaphitidae. The genus is known lived during the Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ... and was first described in 1910. The genus contains five species, ''Y. bladenensis'', ''Y. orbignyi'', ''Y. planus'', ''Y. puerculus'', and ''Y. subevolutus''. ''Yezoites'' was first discovered in the Upper Cretaceous Yezo Group, Hokkaido, Japan and has since been identified in Antarctica, Denmark, France, Madagascar, and the United States. The shell has wide spaced ribbing. References Ammonitida genera Scaphitidae Cretaceous animals of Africa Coniacian genus first appearances Santonian genus extinctions {{Ammonitida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heteromorph
The Ancyloceratina were a diverse suborder of ammonite most closely related to the ammonites of order Lytoceratina. They evolved during the Late Jurassic but were not very common until the Cretaceous period, when they rapidly diversified and became one of the most distinctive components of Cretaceous marine faunas. They have been recorded from every continent and many are used as zonal or index fossils. The most distinctive feature of the majority of the Ancyloceratina is the tendency for most of them to have shells that are not regular spirals like most other ammonites. These irregularly-coiled ammonites are called heteromorph ammonites, in contrast to regularly coiled ammonites, which are called homomorph ammonites. Biology The biology of the heteromorph ammonites is not clear, but one certainty is that their uncoiled shells would have made these forms very poor swimmers. Open shells, particularly ones with spines and ribs, create a lot of drag; but more importantly, the orien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muramotoceras
''Muramotoceras'' was an unusual genus of heteromorphic ammonite. It was known only from Japan until researchers reported in 2001 that the genus was present in Alaska's Matanuska Formation as well. Its remains likely date to the middle Turonian (from 89.8 to 93.9 million years ago) in both areas. Subsequently it was also described from the Santonian Gosau Group (Austria). See also * List of ammonites This list of ammonites is a comprehensive listing of Genus, genera that are included in the subclass †Ammonoidea, excluding purely vernacular terms. The list includes genera that are commonly accepted as valid, as well those that may be invalid ... Footnotes References * External links Paleotheque Ammonitida genera Nostoceratidae Late Cretaceous ammonites of North America Ammonites of Asia {{ammonitida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gaudryceras
''Gaudryceras'' is an ammonite genus belonging to the family Gaudryceratidae. These cephalopods were fast-moving nektonic carnivores. They lived in the Cretaceous period, from Albian to Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ... stages (105.3 to 66.043 Ma).Sepkoski, JacSepkoski's Online Genus Database – Cephalopodes/ref> Subgenera and species Subg. ''Gaudryceras (Gaudryceras) '' de Grossouvre, 1894 :''Gaudryceras (Gaudryceras) alamedense'' (Smith, 1889) :''Gaudryceras (Gaudryceras) aureum'' (Anderson, 1958) :''Gaudryceras (Gaudryceras) cassisianum'' d'Orbigny, 1850 :''Gaudryceras (Gaudryceras) delvallense'' (Anderson, 1958) :''Gaudryceras (Gaudryceras) denmanense'' (Whiteaves, 1903) :''Gaudryceras (Gaudryceras) mitis'' Hauer, 1866 :''Gaudryceras (Gaudryc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eubostrychoceras
''Eubostrychoceras'' is a genus of helically wound, corkscrew form, heteromorph ammonite which lived during the Upper Cretaceous (M Turonian - Campanian). The genus is included in the ancycleratid family Nostoceratidae. The shell of ''Eubostrychoceras'' is a loosely to tightly wound spiral forming a corkscrew with an open, empty umbilicus in the middle. coiling is commonly dextral (right hand). Coils are covered by moderately strong, straight transverse ribs. The aperture, or apertural end, reverses general direction and points upwards or back towards to apex. Sutures are moderately complex. The siphuncle is located mid flank. ''Eubostrychoceras'' has a widespread distribution in the Upper Createous and has been found in Antarctica, Japan, Spain, the far east of Russia, Alaska, Vancouver Island, U.S. western interior, Germany, and Madagascar. In 2001 it was reported from Alaska's Matanuska Formation as well. ''E. japonicum'' is Turonian, and likely confined to the middle Turon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles (muscular hydrostats) modified from the primitive molluscan foot. Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology. Cephalopods became dominant during the Ordovician period, represented by primitive nautiloids. The class now contains two, only distantly related, extant subclasses: Coleoidea, which includes octopuses, squid, and cuttlefish; and Nautiloidea, represented by ''Nautilus'' and ''Allonautilus''. In the Coleoidea, the molluscan shell has been internalized or is absent, whereas in the Nautiloidea, the external shell remains. About 800 living species of cephalopods have been ident ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded by the Cenomanian Stage and underlies the Coniacian Stage. At the beginning of the Turonian an oceanic anoxic event (OAE 2) took place, also referred to as the Cenomanian-Turonian boundary event or the "Bonarelli Event". Stratigraphic definition The Turonian (French: ''Turonien'') was defined by the French paleontologist Alcide d'Orbigny (1802–1857) in 1842. Orbigny named it after the French city of Tours in the region of Touraine (department Indre-et-Loire), which is the original type locality. The base of the Turonian Stage is defined as the place where the ammonite species '' Watinoceras devonense'' first appears in the stratigraphic column. The official reference profile (the GSSP) for the base of the Turonian is located in the Roc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teredolites
''Teredolites'' is an ichnogenus of trace fossil, characterized by borings in substrates such as wood or amber. Club-shaped structures rimming mid-Cretaceous Burmese amber were formerly identified as the fungal sporocarps ''Palaeoclavaria burmitis''. a 2018 study re-identified the structures as domichnia Trace fossils are classified in various ways for different purposes. Traces can be classified taxonomically (by morphology), ethologically (by behavior), and toponomically, that is, according to their relationship to the surrounding sedimentary la ... (crypts) bored in the amber nodules by bivalves of the pholadid subfamily Martesiinae. The borings are comparable with ''Teredolites clavatus'' and ''Gastrochaenolites lapidicus'' . Due to the substrate of the Myanmar borings being amber, the term Amberground was coined. See also * Ichnology References External links Chuck D. Howell's Ichnogenera Photos Boring fossils Paja Formation {{trace-fossil-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucula
''Nucula'' is a genus of very small saltwater clams. They are part of the Family (biology), family Nuculidae. Fossil records This genus is very ancient. Fossils are known from the Arenig to the Quaternary (age range: from 478.6 to 0.0 million years ago). Fossils are found in the marine strata all over the world. Description Shells of species within this genus can reach a size of about . They are equivalve, symmetrical, approximately triangular. The surface has fine concentric growth lines. These clams live in the muddy sand close to the sediment surface at a depth of 20 to 200 meters. Species Nowadays there are still many species of this genus, which have had virtually no change in the course of time. Species within the genus ''Nucula'' include: * ''Nucula annulata'' Hampson, 1971 * ''Nucula atacellana'' Schenck, 1939 - cancellate nutclam * ''Nucula austrobenthalis'' Dell, 1990 * ''Nucula beachportensis'' Verco, 1907 * ''Nucula benguelana'' (A. H. Clarke, 1961) * ''Nucu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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