Silurian facts for kids

Cooksonia, earliest vascular plant, middle Silurian

The Silurian was the period from the end of the Ordovician, about 443.4 million years ago (mya) to the beginning of the Devonian period, about 419 mya.

As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by several million years. The base of the Silurian is set at a major extinction when 60% of marine species were wiped out, the Ordovician-Silurian extinction events.

First terrestrial biota

The Silurian was the first period to see macrofossils of biota on land, in the form of moss forests along lakes and streams as well as millipedes and scorpions colonizing the land later in the period. The fossil record of Sea Scorpions reached it's greatest extent in the middle silurian,about 430 million years ago.

The first fossil records of vascular plants, that is, land plants with tissues that carry food, appeared in the second half of the Silurian period. The earliest known representatives of this group are the Cooksonia (mostly from the northern hemisphere) and Baragwanathia (from Australia). A primitive Silurian land plant with xylem and phloem but no differentiation in root, stem or leaf, was much-branched Psilophyton. This plant reproducied by spores and respired through stomata on every surface, and probably photosynthesizing in every tissue exposed to light.

Some evidence suggests the presence of primitive predatory arachnids and myriapods in Late Silurian rocks. Predatory invertebrates would indicate that simple food webs were in place that included non-predatory prey animals.

Images for kids

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  Ordovician-Silurian boundary on Hovedøya, Norway, showing brownish late Ordovician mudstone and later dark deep-water Silurian shale. The layers have been overturned by the Caledonian orogeny.

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  Fossils of the late Silurian sea bed

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  Silurian sea bed fossils collected from Wren's Nest Nature Reserve, Dudley UK

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  Crinoid fragments in a Silurian (Pridoli) limestone (Saaremaa, Estonia)

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  Silurian sea bed fossils collected from Wren's Nest Nature Reserve, Dudley UK

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  Eurypterus, a common Upper Silurian eurypterid

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  Poraspis, a genus of armored jawless fish from the Late Silurian of Canada, Norway, and the U.S.

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  Trilobites were still diverse and common in the Silurian. Fossils of Calymene celebra are extremely abundant in parts of central USA.

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  Halysites was a Tabulate coral, an extinct group that lived through the Paleozoic

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  Parioscorpio was an enigmatic arthropod from the Silurian of Wisconsin

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  A Dalmanites limulurus specimen from Silurian strata of New York

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  A rock containing several geodized pentamerid brachiopods from strata in Indiana

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  Entelognathus primordialis was a Placoderm fish from the late Silurian

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  Jamoytius was an enigmatic vertebrate that is possibly related to Anaspid fish

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  Pterygotus was a giant eurypterid that had a nearly cosmopolitan distribution

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  Sphooceras was a Nautiloid cephalopod found in Silurian strata of the Czech Republic

See also

In Spanish: Silúrico para niños