Didymograptus definitions

Didymograptus

Didymograptus is an extinct genus of graptolite with four rows of cups. ...
Found on http://en.wikipedia.org/wiki/Didymograptus

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Didymograptus

genus of graptolites (an extinct group of colonial animals related to primitive chordates) found as fossils in Early and Middle Ordovician marine ...
Found on http://www.britannica.com/eb/a-z/d/46

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