ECOS Guide to the Ecology of the Northern Rockies
 
   
 

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Paleozoic Eon

543 – 248 million years ago (Paleozoic Era)


Pangea - the supercontinent as it looked
around 200 million years ago.
Illustration: USGS
Western Montana was not a mountainous region during the Paleozoic Era.  In fact, Montana was beneath a shallow sea for much of the time.  Sediment was deposited in the shallow sea, burying the Belt formations.  These younger sediments preserved the first plant and animal fossils. 

Just before the end of the Paleozoic Era, plate tectonic processes caused most of the continents to join together, forming another ‘supercontinent’ called Pangea.  Eastern North America was involved in this event, but it would ultimately affect western Montana. 

The end of the Paleozoic Era is marked by the largest mass extinction ever—the Permian Extinction—in which ~99% of all life was wiped out.

 

 
The ECOS program is sponsored by the University of Montana's Division of Biological Sciences, and the College of Forestry and Conservation. Carol Brewer Program Director, Division of Biological Sciences. Paul Alaback Program Co-Director, College of Forestry and Conservation.
NSF LogoECOS is supported by the GK-12 Program of the National Science Foundation.
Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the National Science Foundation.