Devonian: 416–359 million years ago

Vertebrates venture on to land

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First trees.
Image: Walter Myers
Source: www.arcadiastreet.com

400 million years ago.
Image: Ron Blakey. Altered by Cally Bennet and Fons VandenBerg
Source: Colorado Plateau Geosystems

Devonian

Life on land became more complex as plants developed, insects diversified and one group of fish developed sturdy fins, eventually giving rise to limbs. These were the early tetrapods – the first backboned animals to walk on land. From these first land vertebrates, groups evolved that could roam further from the water.

In shallow seas, reef-forming corals were widespread and shared their environment with forests of sea-lilies and sponges. An array of fishes swam in the oceans, rivers and lakes – armoured placoderms, sharks, ray-finned and lobe-finned fish of all sizes and habits give the Devonian the nickname “The Age of Fishes”. They shared the waters with ferocious predators like sea scorpions and cephalopods. Towards the end of the Devonian, a major extinction event severely affected warm-water marine life, but had a lesser effect on terrestrial life.

Australia was part of the supercontinent Gondwana, near the equator with a warm climate. Volcanoes exploded across central and eastern Victoria late in the Devonian Period. The most spectacular formed when vast blocks of the crust collapsed along faults. Massive turbulent clouds of hot gas, crystals and pumice spewed from the fractures and flowed into the cauldrons and rift valleys. These were amongst the largest volcanoes ever seen in Earth’s history. Mt Macedon and the Dandenongs are remnants of these eruptions.

Photograph of a yellow plastic Tyranasaurus Rex