Mongolia is one of the popular countries that has plethora of dinosaur species. The late Cretaceous (80-70 million years) rock formations produce that most of dinosaur fossils along with their footprints. Shar Tsav is a remarkable site preserving the clear evidence of social behaviors of theropod dinosaurs. The dinosaur track site was discovered in 1995 by Mongolian-Japanese expedition. Since then, over 20,000 dinosaur tracks were recorded and the site has been studied actively by various researchers. The rock formation that includes Shar Tsav track site is considered as Nemegt Formation that formed approximately 70 million years ago. This formation consists of (river) fluvial deposit.
How were dinosaur tracks preserved ?
Dinosaurs walked through and made an impression in the soft sediments such as sand and mud, leaving an imprint in the ground. Over time those footprints were filled with sand or small pebbles and eventually hardened into rock. The footprints were preserved for millions of years and exposed on the surface where we can see them here. However, most of the tracks were destroyed or obliterated by natural erosion such as wind, water or other forces.
Studying dinosaur biology is mostly depended on its skeletal fossil remnants. It is very difficult to get answers for following questions, how and where they lived, how did they walk, approximate weight of individuals, how did predators hunt etc. Fortunately, there is a way to collect information on dinosaur behavior is called paleoichnology. In paleoichnology, paleontologists are able to acquire knowledge about ancient organisms herding behavior, walking style, speed variation, species (trackmakers) types that shared same environment, even snap shot of certain action interspecies relationships (such as predator and its prey) by using only the footprints measurements.
Not every footprint represents the original track. There are multiple types of tracks could be made by walking. True track is this is actual footprint that formed by actual animal. Sometimes the animal’s skin impression could be preserved in it. Undertrack is track made by the pressure of the animal’s weight. Natural cast is a footprint formed in sediment and filled by other sediments that hardened (lithified). The lithified cast preservation, eventually expose on the surface exhibiting three dimensional replica of animal’s foot.