Silurian period

Then by degrees, in the silurian period, the tops of the mountains began to appear, the islands emerged, then disappeared in partial deluges, reappeared, became settled, formed continents, till at length the earth became geographically arranged, as we see in the present day.

[USA], Sept 1 (ANI): Around 420 million years back in the pre-historic Silurian Period, Earth suffered a major mass extinction, which wiped out almost 23 per cent of the marine life.

During the Silurian period, the area where Dudley now stands was covered by coral reefs and tropical seas and the rocks formed there are rich in fossils of the creatures that swam in those waters.

Qilinyu rostrate was an armored bottom-dwelling fish that lived in the Silurian period, from about 444 million years ago to about 419 million years ago.

Evidence from the fossil record tells us that they've been around since the Silurian period, around 430 million years ago; they are efficient predators and have had no need to undergo any marked evolutionary changes.

The Silurian Period was characterized by calcite seas (Stanley 2006), and hardgrounds were common, though probably less abundant than in the Ordovician (Taylor & Wilson 2003).

It wasn't until sometime around 440 million years ago, near the beginning of the Silurian Period, that the record yields tantalizing but rare and fragmentary evidence that jaw-bearing fishes had evolved.

The age of the marine sapropelic originating from algae in the Silurian period. Izvestiya Peterburgskoj Akademii nauk, 1917, Serie VI, 1, 3-26 (in Russian).