Silurian

Definitions

  • WordNet 3.6
    • n Silurian from 425 million to 405 million years ago; first air-breathing animals
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Webster's Revised Unabridged Dictionary
    • a Silurian (Geol) Of or pertaining to the country of the ancient Silures; -- a term applied to the earliest of the Paleozoic eras, and also to the strata of the era, because most plainly developed in that country.☞ The Silurian formation, so named by Murchison, is divided into the Upper Silurian and Lower Silurian. The lower part of the Lower Silurian, with some underlying beds, is now separated under the name Cambrian, first given by Sedwick. Recently the term Ordovician has been proposed for the Lower Silurian, leawing the original word to apply only to the Upper Silurian.
    • n Silurian The Silurian age.
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Century Dictionary and Cyclopedia
    • Silurian Of or belonging to the Silures, a people of ancient Britain, or their country.
    • Silurian In geology, of or pertaining to the Silurian. See II.
    • n Silurian A name given by Murchison, in 1835, to a series of rocks the order of succession of which was first worked out by him in that part of England and Wales which was formerly inhabited by the Silures. The various groups of fossiliferous rocks included in the Silurian had, previous to Murchison's labors, been classed together as one assemblage, and called by the Germans grauwacke, sometimes Anglicized into graywacke (which see), also the Transition series or Transition limestone. In England and Germany these lower rocks have been greatly disturbed and metamorphosed, and have also been frequently invaded by eruptive masses; hence it was not until after considerable progress had been made toward a knowledge of the sequence of the higher fossiliferons groups that the lower (now designated as Silurian and Devonian) began to be studied with success. Almost contemporaneously with the working out of the order of succession of these lower rocks by Murchison in Great Britain, groups of strata of the same geological age, but lying for the most part in almost entirely undisturbed position, began to be investigated on and near the Atlantic coast of the United States, especially in New York, by the Geological Survey of that State, and a little later in Bohemia by Joachim Barrande. Murchison, Barrande, and James Hall, paleontologist of the New York Survey, are all agreed as to the adoption of the name Silurian, and in regard to the essential unity of the series or system thus designated. The Silurian is the lowest of the four great subdivisions of the Paleozoic, namely Silurian, Devonian, Carboniferous, and Permian. When undisturbed and unmetamorphosed, the Silurian is usually found to be replete with the remains of organic forms, of which by far the larger part is marine. The Silurian is divided into an Upper and a Lower Silurian, and each of these again is subdivided into groups and subgroups varying in nomenclature in various countries. The line between the Upper and Lower Silurian is drawn in Great Britain at the top of the May Hill sandstone or Upper Llandovery group; in New York, at the top of the Hudson River or Cincinnati group. The almost entire absence of vertebrates and of land-plants, and the paucity of plant-life in general, are the most striking features of Silurian life. The most prominent forms of the animal kingdom were the graptolites, trilobites, and brachiopods, and of these the first-mentioned are the most characteristic of all, since they range through nearly the whole Silurian, and disappear in the Devonian; while the trilobites, which begin at the same time with the graptolites, continue through the Devonian, and end only with the Carboniferous. As the line between the Silurian and Devonian is commonly drawn in England—namely, so as to include in the former the Ludlow group—the first vertebrates, in the form of a low type of fishes, appear near the top of the Upper Silurian; traces of land-animals (scorpions) have also been found in the Upper Silurian of Sweden and Scotland; and in France, in the Lower (?) Silurian, traces of insect life. A scorpion has also been found in the United States, at Waterville, New York, in the Waterlime group, or near the middle of the Upper Silurian. Mr. Whitfield, by whom the specimen was described, inclines to the opinion that the species, for which he instituted a new genus (Proscorpius), was aquatic and not air-breathing, and that it forms a link between the true aquatic forms like Eurypterus and Pterygotus and the true air-breathing scorpions of subsequent periods. He intimates that the same is likely to be true of the Swedish and Scottish Silurian scorpions. The traces of land-plants in the Silurian are rare, and for the most part of doubtful identification. Algæ, on the other hand, are of somewhat frequent occurrence. As the line between Silurian and Devonian is drawn in the United States—namely, between the Oriskany sandstone and the Cauda-galli grit—there are neither land-animals nor fishes in the Silurian; and the evidence of the existence of land plants lower than the Devonian is for the most part of a very doubtful character. The Silurian rocks are widely spread over the globe, with everywhere essentially the same types of animal life. This part of the series is of importance in the United States, especially in the northeastern Atlantic States and in parts of the Mississippi valley.
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Chambers's Twentieth Century Dictionary
    • adj Silurian si-lū′ri-an belonging to Siluria, the country of the Silures, the ancient inhabitants of the south-eastern part of South Wales: applied by Murchison in 1835 to a series of rocks well developed in the country of the Silures, a subdivision of the Palæozoic, containing hardly any vertebrates and land plants
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Etymology

Webster's Revised Unabridged Dictionary
From L. Silures, a people who anciently inhabited a part of England and Wales

Usage

In literature:

Perhaps we are the trilobites of a new Silurian period; well, trilobites were painfully common, but we need not be.
"The Master-Knot of Human Fate" by Ellis Meredith
Now it will be a moderate computation to allow 25,000,000 years for the deposition of the strata down to and including the Upper Silurian.
"On the Genesis of Species" by St. George Mivart
Barrande, M., on Silurian colonies, 313.
"On the Origin of Species by Means of Natural Selection" by Charles Darwin
Dawson on fossil land plants of Upper Silurian, 158.
"Our Common Insects" by Alpheus Spring Packard
There is less doubt respecting the existences of the Silurian rocks.
"The World's Greatest Books - Volume 15 - Science" by Various
The term Silurian was employed by Barrande, after Murchison, in a more comprehensive sense than was justified by subsequent knowledge.
"Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 3" by Various
SILURIA; or, a VIEW of the SILURIAN and other PRIMEVAL ROCKS, and their IMBEDDED REMAINS.
"Notes and Queries, Number 219, January 7, 1854" by Various
No insects have yet been detected in the Silurian or Old Red Sandstone Systems.
"The Testimony of the Rocks" by Hugh Miller
There are remains in the Silurian which show that there must have been a few fishes at that time.
"The Meaning of Evolution" by Samuel Christian Schmucker
In the north of England this series rests unconformably upon the Lower Old Red and the Silurian.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 3" by Various
Snakes developed in the Silurian Era, some twenty million years ago.
"Carmen Ariza" by Charles Francis Stocking
The ancient rocks, in which these lower forms of life have left their fossils, are known as the Silurian system.
"Earth and Sky Every Child Should Know" by Julia Ellen Rogers
Home, "Silurian Rocks of Great Britain," vol.
"Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 3" by Various
Silurian rocks occupy a large area in South Australia, on both sides of Spencer Gulf.
"The New Gresham Encyclopedia. Vol. 1 Part 3" by Various
The best Silurian sequence is in New South Wales.
"Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 8" by Various
A. Horizontal lower Silurian strata.
"A Manual of Elementary Geology" by Charles Lyell
The Dendroidea alone, however, have this extended range, the Graptoloidea becoming extinct at the close of Silurian time.
"Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 3" by Various
It is believed that insects of this group are represented among Silurian fossils.
"Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 4" by Various
Henceforth, we shall have to regard the silurian fossils as modern.
"The Catholic World; Volume I, Issues 1-6" by E. Rameur
In the Silurian period they constituted the principal portion of the whole Mollusc tribe.
"The History of Creation, Vol. II (of 2)" by Ernst Haeckel
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In poetry:

"Eo--Mio--Plio--whatsoe'er the 'cene' was
That those vacant sockets filled with awe and wonder,--
Whether shores Devonian or Silurian beaches,--
Tell us thy strange story!
"To The Pliocene Skull" by Francis Bret Harte

In news:

Ultra Petroleum Corp. Houston, gauged a Silurian Tuscarora natural gas discovery in Tioga County, Pa. And has greatly expanded its acreage position in the area.
The Gapowo B-1 well on the Bytow concession in Poland encountered overpressured shales in Lower Silurian and Ordovician and greatly elevated gas readings over those in wells on the Saponis concessions.
Poland Silurian Shale Ready for Action.
A set of exceptionally preserved but difficult-to-extract fossils reveals the diverse creatures from a Silurian sea-floor community.
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In science:

Myr bp, in late Ordovician and Silurian period.
Statistical Approach to Gene Evolution
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