The sign says: "This femur, or leg bone, is of the Sauropod family of Dinosaurs and was found in the Jurassic strata in Northern Colorado which lived 135 and 150 million years ago. These were the long necked, long tailed giants, the most spectacular of all Dinosaurs which included the Apatosauras, Diplodocus, and the Camarosaurus, better known as the Brontosaurus. There are a large number of Dinosaurs in this group and there has been considerable disagreement over the various types due to such incomplete material.

From: The Encyclopedia of Dinosaurs
By, Dr. David Norman (?)