|See the world (and its fossils) with UCMP's field notes.
|SEARCH | GLOSSARY | SITE MAP|
Animals have been walking, scurrying, or slithering on this planet for over 540 million years. During the long history of fossil track creation, environments on Earth have gone through many changes. Continents have moved and sea levels have risen and fallen many times click on the graphic at right to see an animation of the movements of the continents over the last 750 million years. As a result, many of the oldest rocks on Earth have been lost through erosion and tectonic plate collisions. Nevertheless, fossil tracks have been found all over the world.
What depositional environments are tracks commonly found in?
Tracks are commonly found in areas associated with streams or rivers. Sediments deposited by rivers and streams are called fluvial deposits and include mud, silt, and sand. The track below (left) was made in mud that is thought to have been deposited by a flooding river. This particular type of track is called Dromaeopodus shandongensis and was probably made by a theropod dinosaur; theropods are a group of bipedal dinosaurs that include Tyrannosaurus and modern birds.
It is also common to find tracks in sediments that were deposited along the shores, or in the shallow waters of lakes (called lacustrine sediments). Below right are tracks of a web-footed bird found in the Green River Formation of Utah, USA. The Green River Formation is made up of lake sediments deposited during the Eocene Epoch and is known for containing many fossil fish skeletons.
Left: Cast of Dromaeopodus shandongensis, a track made by a theropod dinosaur walking along a river after a flood. This track was made in what is now Shandong Province, China, during the Early Cretaceous Period. Most theropod tracks have three toes, but this one only left impressions of two toes. This is because the track was probably made by one of the theropods that had one toe with a very large claw that was held up (or "retracted" like a cat's claw) when the animal walked; the dinosaur that made this track would have been related to the Velociraptor dinosaurs that were featured in the movie, Jurassic Park (UCM 214.112).1 Right: Fossil tracks of a bird with webbed feet, walking in shallow waters of a lake (UCM 230.14)1
Fossil tracks associated with marine environments were commonly formed along the shores or in shallow waters of the ocean. The trace below left is called Isopodichnus and was probably made by an isopod or another type of crustacean. This trail was made in a shallow sea in North America during the Jurassic Period, when a series of inland seas flooded central western North America.
Tracks can also be preserved in eolian deposits. These are sediments that were moved by wind instead of water. Below right is a type of trackway called Paleohelcura. It is thought to have been made by a scorpion walking across sand dunes during the Permian Period.
Left: Isopodichnus arthropod traces in shallow marine sediment (UCM 187.29).1 These traces were associated with pterosaur tracks! Right: Paleohelcura, a possible scorpion trackway on ancient sand dune deposits (UCM 139.97).1
Fossil tracks from around the world
Today, tracks have been found on every continent including Antarctica! But since the continents have moved over time, fossil tracks may have been made on continents that were at a different latitude or orientation on Earth than they are today. Geologists have been able to reconstruct the approximate positions of the continents over time, and can help us figure out where on Earth the original fossil footprints were made. The following are examples of fossil tracksites that have been discovered on each of the current continents. North America
Around 100 million years ago (during the Late Cretaceous Period) global sea levels were high, and a body of water called the Western Interior Seaway split North America into eastern and western land masses (see graphic below left). Large herds of dinosaurs left trackways as they moved north and south along the coastal plain of the western shoreline of the Western Interior Seaway. This extensive series of track-rich coastal plain sediments is called the Dinosaur Freeway.
The Dinosaur Freeway reveals about 80 tracksites in a single rock formation ranging from northern New Mexico to northern Colorado. These sites preserve tracks made by animals of varying sizes, and many indicate that the dinosaurs that made them were moving parallel to each other. Most of the tracks were made by ornithopod dinosaurs (a group of herbivorous dinosaurs that includes duck-billed and iguanodontid dinosaurs), though some were made by bipedal theropod dinosaurs (including shorebirds) and crocodilians.
One easily accessible fossil site along the Dinosaur Freeway is the Dinosaur Ridge portion of the Morrison-Golden Fossil Area National Natural Landmark near Denver, Colorado. This area contains many ornithopod and theropod tracks. The tracks are found in different layers of sandstone, indicating that the animals walked through the area at different times.
Left: Map of North America during the Cretaceous Period, when the Western Interior Seaway split the continent. The Dinosaur Freeway was on the west side of the seaway, in what is now the western United States. The star marks Dinosaur Ridge, a site where dinosaurs made tracks on the shoreline when the Western Interior Seaway was not as extensive as in this image. Map courtesy of the U.S. Geological Survey. Right: Cast of Caririchnium, an ornithopod dinosaur track from Dinosaur Ridge, a site along the Dinosaur Freeway in the western United States (UCM 209.1).1
Left: Reconstruction of the distribution of the continents during the early Jurassic Period, around 25 million years before the tracks at the Galinha site in Portugal were made. The red star denotes where Portugal was at that time, an island situated between the rest of Europe, North America, and Africa. Adapted from a map by C.R. Scotese, PALEOMAP Project (www.scotese.com). Right: Sauropod tracks at the Galinha fossil track site near Fátima, Portugal. Photo by Ines Saraiva (CC BY 2.0).
Left: Map of distribution of the continents near the end of the Cretaceous Period, 66 million years ago. The star marks the location of what is now Bolivia. Adapted from a map by C.R. Scotese, PALEOMAP Project (www.scotese.com). Right: Fossil tracks at Cal Orck'o, Bolivia, tilted at a steep angle. Photo by Jerry Daykin (CC BY 2.0).
Left: Map of the modern world. The current position of the continents is very close to where they were 3.6 million years ago. The star marks Tanzania, where the Laetoli tracks were found. Adapted from a map by C.R. Scotese, PALEOMAP Project (www.scotese.com). Right: Cast of part of a trackway named Praehominipes laetoliensis, which are hominin tracks from Laetoli (UCM 230.115).1 The entire original trackway (from which the cast was made) is thought to have been made by three individuals two adults and a child.
Left: Reconstruction of the distribution of the continents during the Late Cretaceous Period. Adapted from a map by C.R. Scotese, PALEOMAP Project (www.scotese.com). Right: Cast of Uhangrichnus, web-footed bird tracks from the Upper Cretaceous Uhangri Formation of South Korea (UCM 214.143).1
Left: Map of the world during the Late Cretaceous Period. The star marks the area of Lark Quarry Dinosaur Trackways site. Adapted from a map by C.R. Scotese, PALEOMAP Project (www.scotese.com). Right: Photograph of some of the Lark Quarry Dinosaur Trackways. The large tracks in the left side of the photo are thought to have been made by a large predator. A building has been erected around the fossils to protect them. Original photo by me_whynot (CC BY 2.0).
Left: Map of the world during the Triassic Period, when many of today's continents were part of a supercontinent called Pangea. Notice how Antarctica was connected to Africa and India. Adapted from a map by C.R. Scotese, PALEOMAP Project (www.scotese.com). Right: Early synapsid track from the Triassic Period of Antarctica. Image from MacDonald et al. 1991.
A reconstruction of the arrangement of the continents during the Triassic Period that is supported by the distribution of certain fossils. Fossils of Lystrosaurus, for example, have been found in Antarctica, Africa, and India. Since this animal was terrestrial, the fact that it is found on these continents offered early evidence that these land masses were once connected. Image courtesy of the U.S. Geological Survey.
Azain, J., and J. Wright. 2005. Effects of slope and temperature on the morphology of experimental spider and scorpion trackways. Geological Society of America Abstracts with Programs 37(6):6.
dos Santos, V.F., C.M. da Silva, and L.A. Rodrigues. 2008. Dinosaur track sites from Portugal: Scientific and cultural significance. Oryctos 8:77-88.
Metz, R. 1998. Nematode trails from the late Triassic of Pennsylvania. Ichnos 5(4):303-308.
Fortey, R.A., and A. Seilacher. 1997. The trace fossil Cruziana semiplicata and the trilobite that made it. Lethaia 30(2):105-112.
Huh, M., K.G. Hwang, I.S. Paik, C.H. Chung, and B.S. Kim. 2003. Dinosaur tracks from the Cretaceous of South Korea: Distribution, occurrences, and paleobiological significance. Island Arc 12(2):132-144.
Jensen, S., M.L. Droser, and J.G. Gehling. 2006. A critical look at the Ediacaran trace fossil record. Pp. 115-157 in S. Xiao and A.J. Kaufman (eds.), Neoproterozoic Geobiology and Paleobiology. Springer, Dordrecht, The Netherlands.
Leakey, M.D., and R.L. Hay. 1979. Pliocene footprints in the Laetoli Beds at Laetoli, northern Tanzania. Nature 278:317-323.
Li, R., M.G. Lockley, P.J. Makovicky, M. Matsukawa, M.A. Norell, J.D. Harris, and M. Liu. 2008. Behavioral and faunal implications of Early Cretaceous deinonychosaur trackways from China. Naturwissenschaften 95(3):185-91.
Lieberman, B.S. 2002. Phylogenetic analysis of some basal Early Cambrian trilobites, the biogeographic origins of Eutrilobita, and the timing of the Cambrian Radiation. Journal of Paleontology 76(4):692-708.
Liu, A.G., D. McIlroy, and M.D. Brasier. 2010. First evidence for locomotion in the Ediacara biota from the 565 Ma Mistaken Point Formation, Newfoundland. Geology 38(2):123-126.
Lockley, M.G., and A.P. Hunt. 1995. Dinosaur Tracks and Other Fossil Footprints of the Western United States. Columbia University Press, New York. 338 pp.
Lockley, M.G., and C.A. Meyer. 2000. Dinosaur Tracks and Other Fossil Footprints of Europe. Columbia University Press, New York. 360 pp.
Lockley, M.G., A.S. Schulp, C.A. Meyer, G. Leonardi, and D.K. Mamani. 2002. Titanosaurid trackways from the Upper Cretaceous of Bolivia: Evidence for large manus, wide-gauge locomotion and gregarious behavior. Cretaceous Research 23:383-400.
MacDonald, D.I.M., J.L. Isbell, and W.R. Hammer. 1991. Vertebrate trackways from the Triassic Fremouw Formation, Queen Alexandra Range, Antarctica. Antarctic Journal of the United States 26(5):20-22.
Mayor, A. 2005. Fossil Legends of the First Americans. Princeton University Press, Princeton, New Jersey.
McCrea, R.T., M.G. Lockley, and C.A. Meyer. 2001. Global distribution of purported ankylosaur track occurrences. Pp. 413-454 in K. Carpenter (ed.), The Armored Dinosaurs. Indiana University Press: Bloomington, Indiana.
Mojzsis, S.J.,G. Arrhenius, K.D. McKeegan, T.M. Harrison, A.P. Nutman, and C.R.L. Friend. 1996. Evidence for life on Earth before 3,800 million years ago. Nature 384(7):55-59.
Romilio, A., R.T. Tucker, and S.W. Salisbury. 2013. Reevaluation of the Lark Quarry Dinosaur Tracksite (Late Albian-Cenomanian Winton Formation, Central-Western Queensland, Australia): No Longer a Stampede? Journal of Vertebrate Paleontology 33(1):102-120.
Voight, S., D.S. Berman, and A.C. Henrici. 2007. First well-established track-trackmaker association of Palezoic terapods based on Ichniotherium trackways and diadectid skeletons from the Lower Permian of Germany. Journal of Vertebrate Paleontology 27(3):553-570.
Walker, J.D., J.W. Geissman, S.A. Bowring, and L.E. Babcock (compilers). 2012. Geologic Time Scale v. 4.0. Geological Society of America.
Weimer, R.J., and R.A. Erickson. 1976. Lyons Formation (Permian), Golden-Morrison area, Colorado. Pp. 123-138 in R.C. Epis and R.J. Weimer (eds.), Studies in Colorado Field Geology. Professional Contributions of Colorado School of Mines 8.
White, T.D., and G. Suwa. 1987. Hominid footprints at Laetoli: Facts and interpretation. Physical Anthropology 72(4):485-514.
Wolfe, K.J. 1990. Trace fossils as paleoenvironmental indicators in the Taylor Group (Devonian) of Antarctica. Palaeogeography, Palaeoclimatology, Palaeoecology 80:301-310.
HOME | SEARCH | GLOSSARY | SITE MAP | FREQUENTLY-ASKED QUESTIONS