Describe changes observed of a trilobites Glabella as it evolves over geological time frame?

Question

discuss the importance of this change

Answer 1

I hope you will get your answer if you read carefully the following article about TRILLOBITES GLABELLA

http://icb.oxfordjournals.org/cgi/conten...

Read Why Trilobites Glabella here

http://icb.oxfordjournals.org/cgi/conten...

This article could be helpful as well

http://www.univ-lille1.fr/gepv/downloads...

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Major Events in the History of Life  

... wiped out the first microbes to evolve, again and again. ... Trilobites are ... the extremely inflated glabella which protrudes forward over ...

http://www.peripatus.gen.nz/Paleontology...