How to look at dinosaur tracks

April 30, 2007

A new study appearing in the May issue of The Journal of Geology provides fascinating insight into the factors geologists must account for when examining dinosaur tracks. The authors studied a range of larger tracks from the family of dinosaurs that includes the T. Rex and the tridactyl, and provide a guide for interpreting the effects of many different types of erosion on these invaluable impressions.

"Well-preserved vertebrate tracks in the rock record can be an invaluable source of information about foot morphology, soft tissue distribution, and skin texture," write Jesper Milàn (Geological Institute, University of Copenhagen) and David B. Loope (Department of Geosciences, University of Nebraska, Lincoln). "However, in most instances, the tracks are less than perfectly preserved, and sometimes they can be barely recognizable as tracks at all."

With this in mind, Milàn and Loope sought to describe and categorize different levels of preservation. For example, dinosaur tracks may still exist as true tracks, that is, the original prints left in the ground by the dinosaur. True tracks preserve many of the anatomical details of the foot, such as number of digits and impressions of claws.

However, the true tracks may be filled with sediment or the original tracked surface may have eroded away. In the latter case, erosion may expose prominent layers of concentric circles extending from the former location of the true track. These "undertracks" reveal the squishing and displacement of sand when the heavy dinosaur took a step.

"The tracks and undertracks of large theropods found in the [Middle Jurassic] Entrada Sandstone at the studied locality come in a wide range of morphologies, mainly as a result of present-day erosion that has exposed the track-bearing surfaces at different depths," the researchers explain. "[They] demonstrate that great care should be taken when describing fossil footprints that have been exposed to subaerial erosion, because the shape, dimensions, and general appearance of the footprint become seriously altered by erosion."

Geologists also must account for whether the step was taken on a sloped surface or on a horizontal surface, and whether it was taken during dry season or wet season.

For example, estimating foot length from tracks can be inaccurate without these considerations - the more erosion that has occurred, the larger the apparent dimensions of the track. Applications of this apparently larger foot size derived from an undertrack may lead to calculations of higher estimated hip length, and, as the authors point out, may also lead to slower speed estimates.
-end-
One of the oldest journals in geology, The Journal of Geology has since 1893 promoted the systematic philosophical and fundamental study of geology. The Journal of Geology publishes research on geology, geophysics, geochemistry, sedimentology, geomorphology, petrology, plate tectonics, volcanology, structural geology, mineralogy, and planetary sciences.

Jesper Milàn and David B. Loope, "Preservation and Erosion of Theropod Tracks in Eolian Deposits: Examples from the Middle Jurassic Entrada Sandstone, Utah, U.S.A." The Journal of Geology: 115, p. 375-386.

University of Chicago Press Journals

Related Dinosaur Articles from Brightsurf:

Cracking the secrets of dinosaur eggshells
Since the famous discovery of dinosaur eggs in the Gobi Desert in the early 1920s, the fossilized remains have captured the imaginations of paleontologists and the public, alike.

Dinosaur feather study debunked
A new study published in ''Scientific Reports'' provides substantial evidence that the first fossil feather ever to be discovered does belong to the iconic bird-like dinosaur, Archaeopteryx.

How to weigh a dinosaur
A new study looks at dinosaur body mass estimation techniques revealing different approaches still yield strikingly similar results.

How dinosaur research can help medicine
The intervertebral discs connect the vertebrae and give the spine its mobility.

New species of dinosaur discovered on Isle of Wight
A new study by Palaeontologists at the University of Southampton suggests four bones recently found on the Isle of Wight belong to new species of theropod dinosaur, the group that includes Tyrannosaurus rex and modern-day birds.

First dinosaur eggs were soft like a turtle's
New research suggests that the first dinosaurs laid soft-shelled eggs -- a finding that contradicts established thought.

To think like a dinosaur
Palaeontologists from St Petersburg University have been the first to study in detail the structure of the brain and blood vessels in the skull of the ankylosaur Bissektipelta archibaldi.

New feathered dinosaur was one of the last surviving raptors
Dineobellator notohesperus lived 67 million years ago. Steven Jasinski, who recently earned his doctorate from the School of Arts and Sciences working with Peter Dodson, also of the School of Veterinary Medicine, described the find.

The dinosaur in the cupboard under the stairs
The mystery surrounding dinosaur footprints on a cave ceiling in Central Queensland has been solved after more than a half a century.

How did dinosaur parents know when their kids had a fever?
How Did Dinosaur Parents Know When Their Kids Had a Fever?

Read More: Dinosaur News and Dinosaur Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.