0 from or referring to the period of time between about 445 and 420 million years ago, in which fish with jaws (= mouth bones) and some plants and small animals on land first appeared:
1 the period of time between about 445 and 420 million years ago, in which fish with jaws (= mouth bones) and some plants and small animals on land first appeared:
Very recently, discoveries of some new and very well-preserved thelodonts from the Silurian of British Columbia were announced.
The underlying Siktefjellet Group is likely to be Late Silurian in age, although there is no direct fossil evidence of this.
It has a very local feel with its sandstone dressings, and is rendered in rough cast, a common practice in areas like this where the Silurian stone was weak.
Many of these had at one time been volcanoes, the lava from which had flowed over and covered the Silurian formation in which the gold bearing quartz was found.
Currently, biostratigraphic intervals averaging 500 000 million years are routinely recognized in the Silurian.
Within a few years he had defined and classified three important periods of geological development, the Silurian, Devonian and Permiany.
By the late Silurian, colonization of the changing land with its newly emerging continents was well under way.
