What did Earth look like in the Silurian? (443.1–419.62 Ma)

Warm shallow seas spread widely; jawed fish appeared along with the first land animals and vascular plants.

Key events of this period

Early jawed vertebrates
430 Ma
Jawed vertebrates already existed by 430 million years ago. Chinese tooth fossils named Qianodus, reported in 2022, date to about 439 million years ago. These tiny tooth whorls, mostly under 2.5 millimetres, reveal an earlier history without pinpointing the first jaw’s origin.
References: Chinese Academy of Sciences: Rare Fossil Teeth from China Overturn Long-held Views about Evolution of Vertebrates
Caledonian Orogeny
420 Ma
As the Iapetus Ocean closed, Laurentia and Baltica collided and Avalonia joined them, building the Caledonian mountain belt. Around 420 million years ago represents one stage of this prolonged process, recorded in rocks across Scotland, Greenland and Scandinavia.
References: Lewisian, Torridonian and Moine rocks of Scotland: an introduction — British Geological Survey / Geological Conservation Review