The Triassic Period.

Triassic

The first period of geological time that dinosaurs appeared on Earth was the Triassic. Our first fact files will cover all the prehistoric fauna found during this time but for the time being here is a post regarding the Triassic period itself. Enjoy!

Time Scale:

The Triassic is a period of time which extends from 252.2 to 208 Mya (million years ago). The name Triassic was coined by German geologist Friedrich Von Alberti in 1834, and relates to the three distinct rock layers that formed during the era. These rock layers can be seen throughout Germany and northwestern Europe and are formed of a layer of red beds, capped by a layer of chalk, followed by black shales.

  • Late Triassic:
         Rhaetian (209.5 – 208 Mya)
         Norian (223.4 – 209.5 Mya)
         Carnian (235 – 223.4 Mya)
  • Middle Triassic:
         Ladinian (239.5 – 235 Mya)
         Anisian (241.1 – 239.5 Mya)
  • Early Triassic:
         Olenekian (245 – 241.1 Mya)
         Induan (252.2 – 245 Mya)

Fauna:

The Triassic follows a period of time known as the Permian, and began in the wake of the Permian-Triassic extinction event; an event which left the Earth’s biosphere impoverished. Terrestrial life did not fully recover and diversify until midway through the Triassic era. The shelled, marine-dwelling, ammonites recovered, expanding from a single line which survived the Permian extinction. The fish fauna for the period remained very uniform, highlighting the fact that very few fish families survived through to the Triassic. Despite this, there were a large number of marine reptiles present throughout the Triassic. These included pachypleurosaurs, nothosaurus, placodonts, the first plesiosaurs and the highly successful ichthyosaurs.

On land, the early Triassic period was dominated by basal amphibians and a handful of therapsids (the ancestors of mammals), which had managed to survive the extinction event. However as the Triassic period progressed the therapsids were slowly displaced by archosaur reptiles (the ancestors of dinosaurs). The increase in archosaur numbers likely forced the surviving therapsids and their mammalian succesors to live as small, mainly nocturnal insectivores. The archosaurs on the other hand, evolved at a rapid pace, with different clades of archosaur evolving into different things. By the mid-Triassic the first pterosaurs and dinosaurs were present; but shared land space with a number of other reptile groups, including the aetosaurs, the rhynchosaurs, the first turtles, and the first crocodilians (the sphenosuchians).

Geography & Climate:

During the Triassic, almost all the Earth’s land mass was concentrated into a single super-continent, known as Pangea. The mid-Traissic saw Pangea begin to gradually rift into two separate landmasses, Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry, with deserts spanning much of Pangaea’s interior. However, the climate shifted and became more humid as Pangaea began to drift apart. There is no evidence of glaciation at or near either pole; in fact the polar regions were moist and temperate, a climate ideally suited for the reptilian creatures which dominated the Triassic time era.

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