About the blog: What Things Are Made Of

AMERICA'S GLOBAL DEPENDENCY FOR NEARLY EVERYTHING


The United States relies on imports for dozens of commodities in everyday use. Often enough, that reliance is 100%. In this book I aim to provide awareness of the hidden geology and mineralogy behind common things, and to develop an appreciation for the global resource distribution that underpins our society. While concerns about oil import reliance are in the news every day, our needs for other minerals are comparable and are typically unknown even to technologically aware Americans.





Friday, March 2, 2012

Ordovician trilobites


Today's post is from my History of the Earth Perpetual Calendar for March 4.

The diversity and abundance of trilobites during Ordovician time was similar to that of the Cambrian. Together with brachiopods, trilobites were the dominant (or most numerous) marine animals in Ordovician seas. Ordovician trilobites seem to have had better developed eyes than their Cambrian ancestors.

The trilobites here are Triarthrus becki (left) and Bumastus trentonensis (right).



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