ChemMatters - October 2016

Meet SUE

Consider the most recognizable examples of fossils—those from dinosaurs. One notable example is a Tyrannosaurus rex named SUE. In the years that followed its death, the body of this T. rex decomposed, but not all of its remains were lost. Some underwent physical and chemical processes that converted them into rock. The typical natural processes that lead to the total decomposition of a dying body were interrupted, and a rock-like copy of the skeleton was formed that lasted for millions of years until August 1990 when paleontologist Sue Hendrickson discovered it.

The dinosaur was named SUE in her honor (even though no one knows whether the dinosaur was actually female). At 12. 9 meters (40.5 feet) long, 4 meters ( 13 feet) tall at the hip, and with 90% of its bone volume recovered, SUE is the largest and most complete fossilized T. rex ever found.

SUE is the largest and best preserved

T. rex dinosaur ever found.

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Sue Hendrickson and Pete
Larson pose at the site
where SUE was
excavated.

The T. rex dinosaur named SUE was unveiled at the Field Museum in Chicago, Ill., on May 17, 2000.

When you see the skeleton of an animal that died millions of years ago—from a small fish to a huge dinosaur—you may wonder how the bones that make up the skeleton lasted so long and did not decay. In fact, these are not actually bones, but rocks that formed in or around the bones. More surprisingly, these bone-looking rocks, also called fossils, are very difficult to form, even though there is a vast record of life that has been preserved in the form of fossils. So, how is it that some living beings seem to avoid decomposition and leave evidence of what they looked like and how they lived millions and millions of years ago? And how exactly are fossils made?