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The ammonites (subclass Ammonoidea ) are a group of extinct cephalopod molluscs , which appeared in the Lower Devonian (about 400 million years ago) and extinct around the Upper Cretaceous-Paleocene limit ( 65.5 ± 0.3 Ma ) without leaving any known descendants.

These are marine animals , characterized by an external shell composed mainly of calcium carbonate, in the form of aragonite , and partly of an organic substance of a protein nature ( conchiolin ). The shell was internally divided by septa into different chambers, of which the mollusk occupied only the last (dwelling chamber). The others, which made up the fragmocono (chambered part of the shell), were used as "air chambers" (similarly to the current Nautilus), filled with gas and chamber liquid to control the buoyancy of the organism. The pressure of the chamber fluids was controlled by a thin, richly vascularized, partly mineralized, tubular organic structure (the siphon), which crossed all the septa and allowed the exchange of fluids from the blood and soft tissues of the animal to the chambers through a process of osmosis . The ammonite could thus vary its depth (within the limits of mechanical resistance of the shell) in a manner similar to the nautiloids still living today. Likely the ammonites, like all known cephalopods, were carnivorous organisms, and according to the available studies they probably developed a large number of different adaptations, from predationactive of marine animals, to microfagia (predation of microorganisms), necrophagia (consumption of meat of dead organisms), and even cannibalism (predation of other ammonites, including conspecific ones).

The shell of the ammonites generally has the shape of a spiral wound on a plane (although some species, called heteromorphic , have a more complex and three-dimensional winding) and it is this characteristic that has determined their name. The appearance of these animals, in fact, vaguely recalls that of a rolled up horn, like that of a ram (the Egyptian god Amon , in Hellenistic and Roman times, was commonly depicted as a man with ram's horns). The famous Roman scholar Pliny the Elder (author of the Naturalis historia treatise ) defined the fossils of these animals ammonis cornua , "Ammon's horns". Ammonite species name often ends inceras , Greek word (κέρας) whose meaning is, in fact, "horn" (eg Pleuroceras which etymologically means horn with ribs). The ammonites are considered the fossils par excellence, so much so that they are often used as a graphic symbol of paleontology .

Due to their extraordinary diffusion in marine sediments all over the world and their rapid evolution , with clear variations in the morphology and ornamentation of the shell, ammonites are guide fossils of exceptional value. They are used in stratigraphy for the dating of sedimentary rocks , especially from the Upper Paleozoic to the whole Mesozoic .

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The Gardener , also known as Portrait of a Young Peasant , is an oil on canvas (61 × 51cm) by Vincent van Gogh , datable to September 1889 and now preserved in the National Gallery of Modern and Contemporary Art in Rome .

The work, considered the most important by the Dutch painter among those present in the Italian public collections, is a masterpiece of Van Gogh's Provençal period and contains some of the fundamental themes of his painting, such as the theme of the portrait, the relationship with nature and the combination of primary and complementary colors.

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Eupolo of Thessaly ( ancient Greek : Εὔπολος; Thessaly , 5th century BC - Thessaly , 4th century BC ) was an ancient Greek boxer .

He is known to have been, in 388 BC , the protagonist of the first case of cheating in the history of the Olympics: he tried to bribe three opposing boxers (Agenore of Arcadia , Pritano of Cyzicus and Formione of Halicarnassus , the latter already winner in the previous Olympics) so that let him win, but the ease with which the opponents allowed themselves to be beaten aroused suspicions that soon revealed the fraud.

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On Wikipedia you can read the biographies and studies of the Nobel Prize winners for 2022 . Visit also the Portal: Nobel Laureates .

• Medicine : Svante Pääbo "for his discoveries on the hominid genome and human evolution".
• Physics : Alain Aspect , John Clauser and Anton Zeilinger "for their experiments with photon entanglement, which made it possible to establish the violation of Bell's inequalities and pioneering work in quantum-related information science".
• Chemistry : Carolyn R. Bertozzi , Morten Meldal and Karl Barry Sharpless «for the development of snap chemistry and bioorthogonal chemistry».
• Literature : Annie Ernaux «for the courage and clinical acuteness with which she reveals the roots, distances and collective bonds of personal memory».
• Pace : Ales Bialiatski , Memorial and Center for Civil Liberties "for the commitment in defense of human rights and the right to criticize power, in defense of citizens' rights for the rights of citizens and against abuses of power, for having documented war crimes ».
• Economics : will be awarded on Monday 10 October at 11:45 am.

Vittorio Alfieri

Born October 8 ...
Giulio Monteverde ( 1837 )
Nils Liedholm ( 1922 )
Sigourney Weaver ( 1949 )

... and dead
Vittorio Alfieri ( 1803 )
Riccardo Bacchelli ( 1985 )
Willy Brandt ( 1992 )

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451 - The first session of the Council of Chalcedon opens .
1600 - San Marino adopts its written constitution.
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It occurs today : the Catholic Church celebrates the memory of Saints John Calabria , Ugo Canefri , Felice di Como and Reparata di Cesarea di Palestina .

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