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17-699: The Berriasian Stage was introduced in scientific literature by Henri Coquand in 1869. It is named after the village of Berrias in the Ardèche department of France . The largely non-marine English Purbeck Formation is in part of Berriasian age. The first rocks to be described of this age were the beds of the English Purbeck Formation, named as the Purbeckian by Alexandre Brongniart in 1829 following description by Henry De la Beche , William Buckland , Thomas Webster and William Henry Fitton . The base of

34-745: A million years. The opening of the Central Atlantic continued as the Mid-Atlantic Ridge spread north to separate the Iberian Peninsula from the banks of Newfoundland and to connect to the Canada Basin in the Arctic Ocean. With the opening of the Labrador Sea , Greenland became a separate tectonic plate and Laurentia became North America . The Proto-Caribbean Sea continued to grow and

51-566: Is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java - Manihiki - Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. The Ontong Java Plateau today covers an area of 1,860,000 km . In the Indian Ocean another LIP began to form at c. 120 Ma,

68-562: Is defined by the base of the Valanginian, which is fixed at the first appearance of calpionellid species Calpionellites darderi . This is just a little below the first appearance of the ammonite species Thurmanniceras pertransiens . Regional terms used in Russia include "Volgian"(which spans perhaps the latest Kimmeridgian, all the Tithonian and an uncertain amount of the lower Berriasian) and

85-562: The Comité des travaux historiques et scientifiques , and from 1871 to 1881, he was a munincipal councillor in Marseille. The mineral " coquandite " commemorates his name; its chemical formula is Sb6O8(SO4)•(H2O). Lower Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous ( chronostratigraphic name) is the earlier or lower of the two major divisions of

102-593: The Cretaceous . It is usually considered to stretch from 145  Ma to 100.5 Ma. Proposals for the exact age of the Barremian–Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining early Aptian Oceanic Anoxic Event 1a (OAE1a) was carbon isotope dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There

119-747: The Kerguelen Plateau – Broken Ridge , together covering 2,300,000 km . Another LIP on the Liaodong Peninsula , China, c.  131–117 Ma, lasted for 10 million years. It was the result of the subduction of the Kula and Pacific plates, which was probably caused by a superplume . During the opening of the South Atlantic the Paraná–Etendeka LIP produced 1.5 million km of basalts and rhyolites , beginning 133 Ma and lasting for

136-637: The Late Jurassic continued to persist. Angiosperms (flowering plants) appeared for the first time during the Early Cretaceous; Archaefructaceae , one of the oldest fossil families (124.6 Ma) was found in the Yixian Formation , China. This time also saw the evolution of the first members of the Neornithes (modern birds). Sinodelphys , a 125 Ma-old boreosphenidan mammal found in

153-682: The Upper Cretaceous stages: Coniacian , Santonian and Campanian (1857). In 1871 he proposed the Berriasian stage of the Lower Cretaceous , named after Berrias , a town in the department of Ardèche . He also conducted geological / paleontological research in Spain , Algeria and Morocco . In 1838 he founded the Muséum d'Aix in Aix-en-Provence. From 1862 to 1870 he was a correspondent member of

170-625: The "Ryazanian" (?upper Berriasian) . Henri Coquand Henri Coquand (1813, in Aix-en-Provence – 1881, in Marseille ) was a French geologist and paleontologist . In 1841 he obtained his doctorate in sciences in Paris , and later served as a professor of geology at the University of Besançon , Poitiers and Marseille . From his geological studies of southwestern France, he introduced

187-691: The Berriasian, which is also the base of the Cretaceous System , has traditionally been placed at the first appearance of fossils of the ammonite species Berriasella jacobi . But this is a species that has a stratigraphically problematic and geographically limited distribution. A global reference profile (a GSSP ) for the Berriasian has been under active consideration by the Berriasian Working Group (ISCS) of IUGS since 2010. A range of contender GSSP localities has been studied in detail by

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204-865: The Mid-Atlantic Ridge reached south into the Proto-Caribbean and South Atlantic, effectively separating South America from Africa, and continued rifting in the northern end completed the longitudinal extent of the Atlantic. In Panthalassa the Ontong-Java Mega-LIP resulted in the formation of new tectonic plates and in the Indian Ocean the Kerguelen LIP began to push India northward. During this time many new types of dinosaur appeared or came into prominence, including ceratopsians , spinosaurids , carcharodontosaurids and coelurosaurs , while survivors from

221-741: The Paraná-Etendeka LIP began to break Africa into three pieces. The Falkland Plateau broke off from southern Africa at 132 Ma and Madagascar ceased to move independently c. 120 Ma. In the Panthalassic Ocean the Pacific Plate continued to grow; the Arctic Alaska-Chukotka terrane formed the Bering Strait. Continued rifting opened new basins in the Indian Ocean, separating India, Antarctica, and Australia. By 110 Ma

238-785: The Working Group including localities as far apart as Mexico, Ukraine, Tunisia, Iraq and the Russian Far East. Several markers have been employed to refine correlations and to work towards defining a base for the Berriasian Stage. These include calcareous microfossils , such as Nannoconus , calpionellids , ammonites , palynological data and magnetostratigraphy , notably magnetozone M19n. The calibration of these markers, especially Nannoconus steinmannii minor , N. kamptneri minor , and Calpionella alpina , within precisely fixed magnetozones give greater precision in trying to identify

255-564: The Yixian Formation, China, is one of the oldest mammal fossils found. The fossil location indicates early mammals began to diversify from Asia during the Early Cretaceous. Sinodelphys was more closely related to metatherians (marsupials) than eutherians (placentals) and had feet adapted for climbing trees. Steropodon is the oldest monotreme (egg-lying mammal) discovered. It lived in Gondwana (now Australia) at 105 Ma. Oil in

272-519: The base of the Alpina Subzone in the middle of magnetozone M19n.2n. This site proposal, of Tré Maroua, was subsequently unsuccessful in a vote of the ISCS (8 votes for and 8 against: 4 not voting); a new working group was formed in 2021. In the western part of the ocean of Tethys , the Berriasian consists of four ammonite biozones , from top to bottom (latest to earliest): The top of the Berriasian stage

289-528: The best position for a boundary. In 2016, the Berriasian Working Group voted to adopt Calpionella alpina as the primary marker for the base of the Berriasian Stage. In 2019, a GSSP for the Berriasian was nominated by a vote of the Berriasian Working Group of the Cretaceous Subcommission (ISCS): it is the profile of Tré Maroua in the Vocontian Basin (Hautes Alpes, France). The GSSP was defined at

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