Palaeo map late Cretaceous Click to enlarge image
late Cretaceous c 125 million years ago Image: Ronald Blakey
© Ronald Blakey Exhibitions

The Triassic was a time of recovery and diversification after the mass extinction at the end of the Permian.

The Triassic was getting hotter and dryer but a large part of Australia was under the influence of a monsoonal regime. The continents were still united as a super-continent called Pangaea and there was little to stop tetrapod animals migrating except climate.


Australia's Triassic facts

Position

  • Most of Australia was within the high latitudes and the south pole lay in Eastern Australia

Climate

  • There were no polar ice caps, so the world’s climate was generally hot and dry with monsoonal polar regions.
  • Carbon dioxide levels were about three times higher than today.

Setting

  • Coal swamps had virtually disappeared. Most of Australia was land but some large sedimentary basins persisted.

Vegetation

  • The vegetation was dominated by the forked seed-fern, Dicroidium with abundant horsetails, club-mosses, ginkgoes, ferns, conifers such as pines and araucarians.

Fossil dicroidium zuberi
Fossil of seed fern, Dicroidium zuberi, from Nymboida, New South Wales, Australia. F 48251. Early Triassic, 245 million years ago Image: Robert Jones
© Australian Museum

Animals

Aquatic environments were dominated by fish and labyrinthodont amphibians.


Labyrinthodont amphibian

Labyrinthodont amphibian, Parotosaurus wadei
Labyrinthodont amphibian, Parotosaurus wadei. Middle Triassic, 240 million years ago. Parotosaurus was a primitive, meat-eating labyrinthodont amphibian. Most labyrinthodonts date to the Triassic, but specimens have been found in Australia from the Jurassic and Early Cretaceous. Image: Anne Musser
© Australian Museum

Dicynodont therapsid, Queensland

Dicynodont therapsid, Queensland
Reconstruction of dicynodont therapsid (mammal-like reptile) from Queensland. Dicynodonts were large plant-eating, mammal-like reptiles (therapsids) that survived the mass extinction event at the end of the Permian. They were on the decline in the Triassic. Image: Anne Musser
© Australian Museum

Eoraptor

eoraptor
Eoraptor was one of the first dinosaurs to appear in the fossil record, with a light-weight skeleton, long tail and five fingers on each hand. Scientists agree that the first dinosaur may also have had these features and looked something like Eoraptor. Image: Anne Musser
© Australian Museum

What was happening in the rest of the world

  • The first dinosaurs, prosauropods, early ornithopods, small predators like Eoraptor and Herrerasaurus appeared.
  • The mammal-like reptiles were declining.
  • The long-tailed pterosaurs rule the air.
  • Sharks, bony fishes and ichthyosaurs inhabit the oceans
  • Early crocodiles, lizards and turtles thrive; insects such as cockroaches and dragonflies flourish
  • Primitive mammals were appearing.