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Protosqualus
''Protosqualus'' ("Primitive Squalus") was a genus of Squalidae, dogfish shark that existed during the Cretaceous. Fossils have been found in Europe (mainly in France, Russia, Germany, Lithuania, The United Kingdom and Ukraine), East Asia (mainly in Japan), Antarctica, Australia, Indian subcontinent, India and South America. The type species is ''Protosqualus sigei'', which was found around an Albian aged deposit in France. There are 6 species which can be differentiated by distinct features in their teeth. Some species show some level of heterodonty, for example ''Protosqualus barringtonensis'' shows a rather high level of heterodonty within its teeth. The oldest specimens are from the Speeton Clay Formation. ''Protosqualus'' teeth are quite common in the Grey Chalk deposit of England. The genus went extinct at the end of the Cretaceous during the Cretaceous–Paleogene extinction event, with the last species in the genus being ''Protosqualus argentinensis'' from southern Argenti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barremian
The Barremian is an age (geology), age in the geologic timescale (or a chronostratigraphy, chronostratigraphic stage (stratigraphy), stage) between 125.77 annum, Ma (million years ago) and 121.4 ± 1.0 Ma (Historically, this stage was placed at 129.4 million to approximately 125 million years ago) It is a subdivision of the Early Cretaceous epoch (geology), Epoch (or Lower Cretaceous series (stratigraphy), Series). It is preceded by the Hauterivian and followed by the Aptian Stage.See Gradstein ''et al.'' (2004) or the online geowhen database (link below) Stratigraphic definitions The original type locality (geology), type locality for the Barremian Stage is in the vicinity of the village of Barrême, Alpes-de-Haute-Provence, France. Henri Coquand defined the stage and named it in 1873. The base of the Barremian is determined by the first appearance of the ammonites ''Spitidiscus, Spitidiscus hugii'' and ''Spitidiscus vandeckii''. The end of the Barremian is determined by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
