This cache is part of a series of other geocaches. The Jim Henson Company has hidden Dinosaur Train themed geocaches nationwide with the help of local PBS stations. To find the location of other Dinosaur Train themed geocaches click here
Each geocache celebrates a dinosaur featured in the Dinosaur Train Field Guide
This geocache is all about Argentinosaurus, a humongous herbivore from the Cretaceous period with a voracious appetite. It was up to 130 feet long and weighed as much as 100 tons! It was as big as 10 tyranosaurs put together. As its name implies, it was found in Argentina.
What is your favorite dinosaur? Be sure to tell us when signing the logbook or logging your find online!
Dinosaur bones have never been discovered in the Chicago area. The Mezozoic Era is missing from the geologic record here. The bedrock consists primarily of much older Sulurian and Devonian layers, and is topped by geologically recent glacial deposits. But that doesn't mean you can't find dinosaurs here.
If you follow the nearby interstate highway 55 to it's end (beginning) a mere 8 miles away, you will see a huge brachiosaur skeleton at N 41° 52.000 W 087° 37.107. If you go inside the building you can see the most famous T-Rex in history, Sue at the Field Museum of Natural History.
This cache is a small Lock & Lock, and is full of little dinosaurs for trading. Note: the cache is hidden very close to a junction of two popular trails, so that it should be easily accessible with small children. So be wary for muggles passing by, and hunt, retrieve, and replace the cache only when you see that the coast is clear. Sit at the other end of the fallen tree while logging and trading, as there is a good chanch someone will walk, bike or jog by. Just be cool; having a snack, taking pictures, faking it, or whatever. Replace the cache with adequate cover that doesn't look obvious.
Most of all, enjoy the cache and the fine trails in these woods. There are plenty of good caches to discover if you keep walking. 
This cache was published with special permission from Groundspeak.