genus of graptolites (extinct, small floating colonial animals related to the primitive chordates), characterized by a frondlike form. Groups of these animals were connected by stalklike structures to a central region. Various forms or species of Clonograptus are important guide, or index, fossils for the correlation of Ordovician rocks (505 to 438 million years ago).
CLONOGRAPTUS
Meaning of CLONOGRAPTUS in English
Britannica English vocabulary. Английский словарь Британика. 2012