The 190 million year old footprints are the size of a 10 pence piece and were discovered in the Dinosaur National Monument, USA. The area was experiencing desert conditions at that time. The small mammals scurried over the sand dunes during the night when conditions were cooler. The following day the footprints were covered by more fine sand and preserved.

There are hundreds of footprints at this site, which makes it special. The tracks could belong to a small mammal called Brasilichnium. The preservation of the footprints is excellent in many cases with some showing signs of individual toe impressions. Mixed in with these mammalian trackways are larger footprints probably made by small dinosaurs and is an indication of the diversity of life in the early Jurassic period in this part of the USA.