Download or read book Ludlow and Pridoli (Upper Silurian) Graptolites from the Arctic Islands, Canada written by Alfred C. Lenz and published by NRC Research Press. This book was released on 2004 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graptolites flourished from earliest Ordovician to Early Devonian, a time range of about 90 million years, and were widely distributed as marine benthic and planktonic colonial organisms around then-world.