The collection described in this portfolio is rare and unique.

First, it is the largest known collection—public or private—in the world, with over 85 footprints. The next largest known collection, owned by a museum, has only 30 footprints.

Second, it includes a variety of footprints—large and small—ranging in size from 72 cm long by 66 cm wide to 8 cm long by 8 cm wide and in weight from 125 kg to .1 kg. Large adult footprints and small infant footprints are included, with the bulk of the entries being adult footprints.

Third, a single extractor assembled this collection over approximately 20 years. The retrieval points were in underground coal mines, eight kilometers from the mine portal. The retrievals were tedious and undertaken at extreme risk to the extractor's safety, as the footprints were extracted from the ceilings of shafts in abandoned mine sections. The retrieval points are now closed to humans and machines, as the source mines have been shut down and sealed due to toxic levels of explosive gases.

Fourth, it includes both handprints and footprints of dinosaurs--but mainly footprints.

Fifth, these tracks were retrieved intact in the original sandstone. The prehistoric vitreous coating is still on the outside of the footprints.

Sixth and most exciting, the collection includes raptor footprints--probably the only ones ever found in the world!

The best estimates are that most footprints came from prehistoric coal swamps, where at least 600-meter-thick strata covered the ancient swamps. The footprint impressions were proper receptacles for flooding ancient rivers and depositing the sandstone materials that filled them.

In what used to be the swamp forests of the delta plains of the Late Cretaceous Period 65 million years ago, dinosaurs left their footprints on the peat surface as they roamed the landscape.

 During storms, many ancient stream channels would overflow their banks, filling sand into these impressions made by the dinosaurs. The peat surface was pliable or flexible, making depressions into the peat quite ordinary. 

The dinosaur footprints are most beautifully preserved on the roofs of certain underground coal mines. Over millions of years, mountains formed on the tops of these ancient peat beds, leaving the coal seams far below the surface topography. When large pieces of continuous mining machinery mined coal out, footprints could be seen on the roofs of certain underground coal mines.

The photographs in this album are all of footprints from dinosaur trackways collected from Spring Canyon #5 Coal Mine near Price, Utah, U.S.A. These footprints, of various shapes and sizes, and more than 25 different species of dinosaurs, date throughout the Late Cretaceous Period.