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The Olenekian (also known as the Yongningzhenian) is a stage
Faunal stage

In chronostratigraphy, a stage is a Geologic record laid down in an single age on the geologic timescale, which usually represents millions of years of deposition....
 of the Early Triassic
Early Triassic

The Early Triassic is the first of three epoch s of the Triassic period . It spans the time between 251 ? 0.4 annum and 245 ? 1.5 Ma . The Permian-Triassic extinction event spawned the Triassic period....
 epoch. It spans the time between 249.7 ± 0.7 Ma
Annum

Annum is one form of the Latin noun meaning year, not a form normally used for derivatives in modern languages: the accusative case Grammatical number of the second declension grammatical gender noun annus , anni ....
 and 245 ± 0.7 Ma (million years ago). The Olenekian is divided into the Smithian and the Spathian age. It is defined as starting near the lowest occurrence of Hedenstroemia or Meekoceras gracilitatis ammonite
Ammonite

Ammonites are an Extinction group of marine animals of the Subclass Ammonoidea in the class Cephalopoda, phylum Mollusca. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific Geologic time scale....
s, and of the conodont
Conodont

Conodonts are extinct chordata resembling eels, classified in the class Conodonta. For many years, they were known only from tooth-like microfossils now called conodont elements, found in isolation....
 Neospathodus waageni.






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The Olenekian (also known as the Yongningzhenian) is a stage
Faunal stage

In chronostratigraphy, a stage is a Geologic record laid down in an single age on the geologic timescale, which usually represents millions of years of deposition....
 of the Early Triassic
Early Triassic

The Early Triassic is the first of three epoch s of the Triassic period . It spans the time between 251 ? 0.4 annum and 245 ? 1.5 Ma . The Permian-Triassic extinction event spawned the Triassic period....
 epoch. It spans the time between 249.7 ± 0.7 Ma
Annum

Annum is one form of the Latin noun meaning year, not a form normally used for derivatives in modern languages: the accusative case Grammatical number of the second declension grammatical gender noun annus , anni ....
 and 245 ± 0.7 Ma (million years ago). The Olenekian is divided into the Smithian and the Spathian age. It is defined as starting near the lowest occurrence of Hedenstroemia or Meekoceras gracilitatis ammonite
Ammonite

Ammonites are an Extinction group of marine animals of the Subclass Ammonoidea in the class Cephalopoda, phylum Mollusca. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific Geologic time scale....
s, and of the conodont
Conodont

Conodonts are extinct chordata resembling eels, classified in the class Conodonta. For many years, they were known only from tooth-like microfossils now called conodont elements, found in isolation....
 Neospathodus waageni. It is defined as ending near the lowest occurrences of genera Japonites, Paradanubites, and Paracrochordiceras; and of the conodont Chiosella timorensis. Archosaurs -- a group encompassing crocodiles, pterosaurs, dinosaurs, and ultimately birds -- are diapsid
Diapsid

Diapsids are a group of reptiles that developed two holes in each side of their skulls, about 300 million years ago during the late Carboniferous period....
 reptiles that first evolved from Archosauriform
Archosauriformes

Archosauriformes are a clade of diapsid reptiles that developed from Archosauromorpha ancestors some time in the Late Permian . These reptiles, which include members of the Family Proterosuchidae and more advanced forms, were originally superficially crocodile-like predatory semi-aquatic animals about 1.5 meters long, with a sprawling elbow...
 ancestors during the Olenekian.

The stage is named for Olenėk in Siberia.

Vertebrate Fauna

  • Gnathorhizids
    Gnathorhizidae

    The Gnanthorhizidae are an extinct family of lungfish that lived from the late Carboniferous until the middle Triassic. Gnathorhizid fossils have been found in North America, Madagascar, Australia, and possibly Eastern Europe and South Africa....


  • Archosaur
    Archosaur

    Archosaurs are a group of diapsid reptiles represented by modern birds and crocodilians. This group also includes extinct non-avian dinosaurs, pterosaurs and relatives of crocodiles....
    s
  • Erythrosuchids
    Erythrosuchidae

    Erythrosuchidae are a family of large Basal archosauromorph carnivores that lived from the later Early Triassic to the early Middle Triassic ....
  • Proterosuchids
    Proterosuchidae

    Proterosuchidae are an early, possibly paraphyletic, assemblage of Basal archosauriformes whose fossils are known from the Latest Permian of Russia and the Early Triassic of southern Africa, Russia, China, Australia, and Antarctica....
  • Crurotarsi
    Crurotarsi

    The Crurotarsi are a group of Archosauria, whose name was erected as a Cladistics#Cladistic classification by Paul Sereno in 1991 to supplant the old term Pseudosuchia....
    • Rauisuchia
      Rauisuchia

      Rauisuchia are a poorly known assemblage of predatory and mostly large Triassic archosaurs. Originally it was believed that they were related to Erythrosuchidae, but it is now known that they are Crurotarsi....


Archosauromorphs (non-archosaurian)

†Non-archosaurian
Paraphyly

In phylogenetics, a group of organisms is said to be paraphyletic if the group contains its most recent common ancestor Common descent but does not contain all the descendants of that ancestor....
 Archosauromorphs of the Olenekian
Taxa Presence Location Description Images
  • Chasmatosuchus
    Chasmatosuchus

    Chasmatosuchus was a large archosauriformes reptile from the early Triassic period of South Africa and China. It is one of the earliest well-known archosauriforms....
   
  • Garjainia
    		•    
  • Sharovipteryx
    Sharovipteryx

    Sharovipteryx , was among the earliest gliding reptiles, from the early Triassic period. It was approximately eight inches long, with an extremely long tail, and weighed about 7.5 grams....
    		•    


    Therapsids (non-mammalian)

    †Non-mammalian
    Paraphyly

    In phylogenetics, a group of organisms is said to be paraphyletic if the group contains its most recent common ancestor Common descent but does not contain all the descendants of that ancestor....
     Therapsids of the Olenekian
    Taxa Presence Location Description Images
    • Kannemeyeria
      Kannemeyeria

      Kannemeyeria was a large dicynodont of the family Kannemeyeriidae, one of the first representatives of the family, and hence one of the first large herbivorous of the Triassic....
    		   


    See also

    • Geologic time scale
      Geologic time scale

      File:Geologic clock.jpgThe geologic time scale is a chronology schema relating stratigraphy to time that is used by geologys and other earth sciences scientists to describe the timing and relationships between events that have occurred during the history of the Earth....