Mean atmospheric O2
Geologic Time Scale
Middle Cambrian Pirania
Pirania was a genus of primitive sponge that populated the ocean floors about 513 million years ago. The stems were hollow with bunches of long spicules attached to them.
Based upon a sketch reconstruction by J.K. Rigby from the book, The Burgess Shale by Harry B. Whittington. Published in 1985 by Yale University Press.
|*AKA St Davids|
Copyright © Walter B. Myers. All rights reserved.
[ Home | What's New | The Graphics | Information | Site Map | ]