Introduction to the Anthozoa

Anthozoans are probably the most famous cnidarians:
they include the corals that build great reefs in tropical waters, as well as sea anemones,
sea fans, and sea pens. They also have a long and diverse fossil record,
extending back at least 550 million years. The oldest anthozoans are probably some of the
polyp-like and sea pen-like fossils from the
Vendian (late Precambrian). A few tens of millions of years later, in the
Cambrian period, the first mineralized coral-like organisms
appeared. True corals of the kind living today did not appear until the middle Triassic,
at about the same time that the first dinosaurs
were evolving.
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