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Polazzodus
''Polazzodus'' is an extinct pycnodontid from the late Cretaceous (early Santonian) of the Polazzo locality of northeastern Italy. The paleoenvironment of Polazzo was a large marine carbonate platform and shallow internal lagoons formed from rudist reefs. ''P. coronatus'' is known from numerous specimens, many of which were very well-preserved. The new genus ''Polazzodus'' was erected based on a number of autapomorphies that distinguished it from similar pycnodontid fish. These include a second dorsal ridge scale (from which the Latin species name, ''coronatus'', is derived), presence of olfactory fenestra on premaxilla, posterodorsal process on cleithrum, and several others. The largest measured recovered specimen was 97 mm (3.8 in), and the smallest was 30 mm (1.2 in), which represented a subadult specimen. ''Polazzodus'', being a low-bodied pycnodont, is most similar morphologically to ''Pycnodus ''Pycnodus'' (from el, πυκνός , 'dense' and el, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pycnodontiformes
Pycnodontiformes is an extinct order of primarily marine bony fish. The group first appeared during the Late Triassic and disappeared during the Eocene. The group has been found in rock formations in Africa, Asia, Europe, North and South America. They were small to middle-sized fish, generally with laterally-compressed deep bodies, some with almost circular outlines, adapted for manuverability in reef-like environments. The group was morphologically diverse containing forms such the very short but deep Gebrayelichthyidae and the horned ''Ichthyoceros,'' both from the early Late Cretaceous of Lebanon. Most, but not all members of the groups had jaws with round and flattened teeth, well adapted to crush food items (durophagy), such as echinoderms, crustaceans and molluscs. Some pyncodontiformes developed piranha like teeth used for eating flesh. Most species inhabited shallow marine reef environments, while a handful of species lived in freshwater or brackish conditions. While rare ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pycnodontiformes Genera
Pycnodontiformes is an extinct order of primarily marine bony fish. The group first appeared during the Late Triassic and disappeared during the Eocene. The group has been found in rock formations in Africa, Asia, Europe, North and South America. They were small to middle-sized fish, generally with laterally-compressed deep bodies, some with almost circular outlines, adapted for manuverability in reef-like environments. The group was morphologically diverse containing forms such the very short but deep Gebrayelichthyidae and the horned ''Ichthyoceros,'' both from the early Late Cretaceous of Lebanon. Most, but not all members of the groups had jaws with round and flattened teeth, well adapted to crush food items (durophagy), such as echinoderms, crustaceans and molluscs. Some pyncodontiformes developed piranha like teeth used for eating flesh. Most species inhabited shallow marine reef environments, while a handful of species lived in freshwater or brackish conditions. While rare ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animalia
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a bilaterally symmetric body plan. The Bilateria include the protostomes, containing animals such as nematodes, arthropods, flatworms, annelids and molluscs, and the deuterostomes, containing the echinode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chordata
A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These five synapomorphies include a notochord, dorsal hollow nerve cord, endostyle or thyroid, pharyngeal slits, and a post-anal tail. The name “chordate” comes from the first of these synapomorphies, the notochord, which plays a significant role in chordate structure and movement. Chordates are also Bilateral symmetry, bilaterally symmetric, have a coelom, possess a circulatory system, and exhibit Metameric, metameric segmentation. In addition to the morphological characteristics used to define chordates, analysis of genome sequences has identified two conserved signature indels (CSIs) in their proteins: cyclophilin-like protein and mitochondrial inner membrane protease ATP23, which are exclusively shared by all vertebrates, tunicates and cep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinopterygii
Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or horny spines (rays), as opposed to the fleshy, lobed fins that characterize the class Sarcopterygii (lobe-finned fish). These actinopterygian fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the link or connection between these fins and the internal skeleton (e.g., pelvic and pectoral girdles). By species count, actinopterygians dominate the vertebrates, and they constitute nearly 99% of the over 30,000 species of fish. They are ubiquitous throughout freshwater and marine environments from the deep sea to the highest mountain streams. Extant species can range in size from ''Paedocypris'', at , to the massive ocean sunfish, at , and the long-bodied oarfish, at . The vast majority of Actinopt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pycnodontidae
Pycnodontidae is an extinct family of ray-finned fishes, ranging from the Triassic period until the Eocene. Genera * '' Acrotemnus'' Agassiz, 1843 * '' Anomoeodus'' Forir, 1887 * ''Athrodon'' Sauvage, 1880 * '' Callodus'' Thurmond, 1974 * ''Coccodus'' * '' Coelodus'' Haeckel * ''Gyrodus'' Agassiz, 1843 * '' Iemanja'' Wenz, 1989 * '' Macromesodon'' Blake, 1905 * '' Microdus'' * '' Micropycnodon'' Hibbard and Graffham, 1945 * '' Neoproscinetes'' De Figueiredo and Silva Santos, 1990 * '' Nonaphalagodus'' Thurmond, 1974 * '' Omphalodus'' von Meyer, 1847 * '' Paleobalistum'' * ''Paramicrodon'' Thurmond, 1974 * '' Polypsephis'' Hay, 1899 * ''Proscinetes'' Gistl, 1848 * '' Pycnodus'' Agassiz, 1835 * '' Pycnomicrodon'' Hibbard and Graffham, 1941 * '' Scalacurvichthys'' Cawley and Kriwet, 2017 * '' Sphaerodus'' Agassiz, 1843 * ''Stemmatodus ''Stemmatodus'' is an extinct genus of prehistoric ray-finned fish that lived in Europe during the Early Cretaceous approximately 129 to 125 milli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pycnodontid
Pycnodontidae is an extinct family of ray-finned fishes, ranging from the Triassic period until the Eocene. Genera * ''Acrotemnus'' Agassiz, 1843 * ''Anomoeodus'' Forir, 1887 * ''Athrodon'' Sauvage, 1880 * ''Callodus'' Thurmond, 1974 * ''Coccodus'' * ''Coelodus'' Haeckel * ''Gyrodus'' Agassiz, 1843 * ''Iemanja'' Wenz, 1989 * ''Macromesodon'' Blake, 1905 * ''Microdus'' * ''Micropycnodon'' Hibbard and Graffham, 1945 * ''Neoproscinetes'' De Figueiredo and Silva Santos, 1990 * ''Nonaphalagodus'' Thurmond, 1974 * ''Omphalodus'' von Meyer, 1847 * ''Paleobalistum'' * ''Paramicrodon'' Thurmond, 1974 * ''Polypsephis'' Hay, 1899 * ''Proscinetes'' Gistl, 1848 * ''Pycnodus'' Agassiz, 1835 * ''Pycnomicrodon'' Hibbard and Graffham, 1941 * ''Scalacurvichthys'' Cawley and Kriwet, 2017 * ''Sphaerodus'' Agassiz, 1843 * ''Stemmatodus'' * ''Tepexichthys'' Applegate, 1992 * ''Thiollierepycnodus'' Ebert, 2020 * ''Typodus'' Quenstedt, 1858 References Pycnodontiformes Triassic first appearanc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin ''creta'', "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation ''Kreide''. The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now- extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. The Santonian is preceded by the Coniacian and is followed by the Campanian.Gradstein ''et al.'' (2004) Stratigraphic definition The Santonian Stage was established by French geologist Henri Coquand in 1857. It is named after the city of Saintes in the region of Saintonge, where the original type locality is located. The base of the Santonian Stage is defined by the appearance of the inoceramid bivalve ''Cladoceramus undulatoplicatus''. The GSSP (official reference profile) for the base of the Santonian Stage is located near Olazagutia, Spain; it was ratified by the Subcommission on Cretaceous Stratigraphy in 2012. The Santonian's top (the base of the Campanian Stage) is informally marked by the extinction of the crinoid '' Marsupites tes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical region. Italy is also considered part of Western Europe, and shares land borders with France, Switzerland, Austria, Slovenia and the enclaved microstates of Vatican City and San Marino. It has a territorial exclave in Switzerland, Campione. Italy covers an area of , with a population of over 60 million. It is the third-most populous member state of the European Union, the sixth-most populous country in Europe, and the tenth-largest country in the continent by land area. Italy's capital and largest city is Rome. Italy was the native place of many civilizations such as the Italic peoples and the Etruscans, while due to its central geographic location in Southern Europe and the Mediterranean, the country has also historically been home ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rudist
Rudists are a group of extinct box-, tube- or ring-shaped marine heterodont bivalves belonging to the order Hippuritida that arose during the Late Jurassic and became so diverse during the Cretaceous that they were major reef-building organisms in the Tethys Ocean, until their complete extinction at the close of the Cretaceous. Shell description The Late Jurassic forms were elongate, with both valves being similarly shaped, often pipe or stake-shaped, while the reef-building forms of the Cretaceous had one valve that became a flat lid, with the other valve becoming an inverted spike-like cone. The size of these conical forms ranged widely from just a few centimeters to well over a meter in length. Their "classic" morphology consisted of a lower, roughly conical valve that was attached to the seafloor or to neighboring rudists, and a smaller upper valve that served as a kind of lid for the organism. The small upper valve could take a variety of interesting forms, including: a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reef
A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock outcrops, etc.—but there are also reefs such as the coral reefs of tropical waters formed by biotic processes dominated by corals and coralline algae, and artificial reefs such as shipwrecks and other anthropogenic underwater structures may occur intentionally or as the result of an accident, and sometimes have a designed role in enhancing the physical complexity of featureless sand bottoms, to attract a more diverse assemblage of organisms. Reefs are often quite near to the surface, but not all definitions require this. Earth's largest coral reef system is the Great Barrier Reef in Australia, at a length of over . Biotic There is a variety of biotic reef types, including oyster reefs and sponge reefs, but the most massive and widely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
