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The Silurian Reef
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In the Silurian period, most creatures still lived in the sea, and the fossils from that time are nearly all of marine animals. Near the shores of the continents, the waters were warm and shallow. There, great reefs, made up mainly of sponges, were able to grow. Trilobites were common, and so were starfish and their relatives the sea lilies. Most of the shellfish were from a group called the brachiopods. The reefs produced masses of limey sediments. These have become fossil-rich limestones.
(A) REEF BUILDERS
Silurian reefs were built from the skeletons of sponges, like this Ischadites.
(B) STALKED STARFISH
Sea lilies or crinoids, like these Gissocrinus, were like upside-down starfish on long stalks.
(C) ANCIENT SNAILS
Some snails, like this Platyceras, lived among the forests of sea lilies.
(D) CORALS
Most Silurian corals were solitary types, like sea anemones in limey cups.
(E) BRACHIOPODS
Brachiopods looked like modern bivalve shellfish because they evolved to have the same life-style.
(F) COMPOUND CORALS
Some corals were made up of many animals packed closely together, like modern types.
(G) TOP AND BOTTOM
Bivalves have a left shell and a right shell. Brachiopods, like Meristina, have a top shell and a bottom shell.
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Previous:
Back
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Book:
Prehistoric Life
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Section:
Prehistoric
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Chapter:
The Silurian Reef
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