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Diggin' For Dinosaurs - Grand Valley

Updated on March 30, 2010

Look for gray X's marking the midpoint of each vertebra. A humerus juts out from the base of the rock; another rock nearby broke away from this arm bone but still bears an impression in the shape of the fossil.

The trail winds past angular boulders of conglomerate sandstone, colored with sea foam and rust lichen, and other rocks coated in dark desert varnish. Embedded in some of these darker rocks are tan shards of petrified wood, which are especially noticeable just past the sheltered bench at the halfway point.

Jurassic-age Morrison Formation rock layers, visible from the high point of the trail, have a distinct greenish tint. This means that they formed under standing water with little air reaching the sediment - advantageous conditions for preserving fossils.

Farther along the trail, four arching sauropod tail vertebrae appear on a rock face. The U-shaped concavity at the base of each backbone distinguishes these as coming from Diplodocus, an 80-foot-long vegetarian. An adjacent gap in the rock here contained limb bones, until the block was cut out and carted off by vandals shortly before the trail's dedication in 1986. That's the risk of such an outdoor exhibit, but Bureau of Land Management palaeontologists Harley Armstrong, the trail's inspiration and official guardian, is determined to educate potential fossil filchers about laws protecting old bones.

Unmarked rocks near the end of the trail contain reddish dinosaur bone fragments, and an Allosaurus leg was found clasped in the roots of a nearby juniper. The last marked fossil stop contains bits of neck vertebrae from what may be either Camptosaurus or Iguanodon. If the latter, it would be much older than any other specimen of this dinosaur.

Along the road to Colorado National Monument in Fruita, 20 miles east of Rabbit Valley, the trail over Dinosaur Hill passes the site where, in 1901, Elmer Riggs of the Field Museum of Natural History bagged one of the finest examples of Apatosaurus excelsus ever found. Although the head, neck, and shoulders had eroded away, Riggs got the rear two-thirds of the skeleton, and part of the tail may still lie deep in the hill. A recent excavation found a few more fragments, as well as a shovel and broom dating to Riggs' excavation. Now the site is immortalized with a bronze plaque that misspells the six-ton behemoth's name much to the disgrace of the memory of the scientists and researchers who worked so hard there.

At the head of this one-mile loop trail, you can see atop a boulder the imprint from a Diplodocus femur. Bronze-headed, lime-green collared lizards dart underfoot as you wind up to the summit, where a bench entices you to admire the view of the Book Cliffs, Grand Mesa, and the monument.

Just outside Grand Junction, surrounded by subdivisions, is Riggs Hill, where Riggs and H.W. Menke struck sauropod gold on July 4, 1900, by unearthing the remains of Brachiosaurus altithorax, the largest dinosaur ever found up to that time. Cement "vertebrae" and a plaque mark the discovery site.

Continued in: Diggin' For Dinosaurs - Dinosaur National Monument

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