For instance, I cannot doubt that all the Silurian trilobites have descended from some one crustacean, which must have lived long before the Silurian age, and which probably differed greatly from any known animal.
Consequently, if my theory be true, it is indisputable that before the lowest Silurian stratum was deposited, long periods elapsed, as long as, or probably far longer than, the whole interval from the Silurian age to the present day; and that during these vast, yet quite unknown, periods of time, the world swarmed with living creatures.
Murchison at their head, are convinced that we see in the organic remains of the lowest Silurian stratum the dawn of life on this planet.
If then we may infer anything from these facts, we may infer that where our oceans now extend, oceans have extended from the remotest period of which we have any record; and on the other hand, that where continents now exist, large tracts of land have existed, subjected no doubt to great oscillations of level, since the earliest silurian period.
The several difficulties here discussed, namely our not finding in the successive formations infinitely numerous transitional links between the many species which now exist or have existed; the sudden manner in which whole groups of species appear in our European formations; the almost entire absence, as at present known, of fossiliferous formations beneath the Silurian strata, are all undoubtedly of the gravest nature.
This one clung to his theory with affectionate fidelity characteristic of originators of scientific theories, and afterward won many of the first scientists of the age to his view, by a very able pamphlet which he wrote, entitled, "Evidences going to show that the hair trunk, in a wild state, belonged to the early glacial period, and roamed the wastes of chaos in the company with the cave-bear, primeval man, and the other Oo"litics of the Old Silurian
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.
The lower country consists of clay-slat and sandstone, containing fossils, very closely related to, bu not identical with, those found in the Silurian
formation of Europe; the hills are formed of white granular quart rock.
The European periphery of the Uralian Ocean (southern part of the vast Paleoasiatic Ocean) in the Silurian
and Devonian was likely a centre of origin and distribution for many groups of benthic organisms.
In 1844, Reverend William Branwhite Clarke, a pastor and geologist, visited Duntroon and discovered fossils from the Silurian
Period at the nearby Woolshed Creek.
This paper focuses on a relatively quiet interval from Late Ordovician (Ashgill) to Late Silurian
times when an enormous volume of sediment eroded from post-Middle Ordovician highlands was deposited in extensive basins on the Ganderian composite plate.
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.